circabc.europa.eu · Web viewEU NON-NATIVE ORGANISM RISK ASSESSMENT SCHEMEName of genus: Ameiurus Rafinesque, 1820 – bullheads Ameiurus brunneus Jordan, 1877 – snail bullhead

EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0

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EU NON-NATIVE ORGANISM RISK ASSESSMENT SCHEME

Name of genus: Ameiurus Rafinesque, 1820 – bullheadsAmeiurus brunneus Jordan, 1877 – snail bullheadAmeiurus catus (Linnaeus, 1758) – white catfish, white bullheadAmeiurus melas (Rafinesque, 1820) – black bullhead,Ameiurus natalis (Lesueur, 1819) – yellow bullhead,Ameiurus nebulosus (Lesueur, 1819) – brown bullhead,Ameiurus platycephalus (Girard, 1859) – flat bullheadAmeiurus serracanthus (Yerger and Relyea, 1968) – spotted bullheadRetrieved [November, 11, 2016] from the Integrated Taxonomic Information System on-line database, http://www.itis.gov.

Author: Deputy Direction of Nature (Spanish Ministry of Agriculture and Fisheries, Food and Environment)Risk Assessment Area: Europe

Peer reviewed by: Emili García-Berthou, Professor of Ecology. University of Girona. Institut of Aquatic Ecology. 17003 Girona, Catalonia, Spain. Tel.: +34 972 41 8369. http://www.udg.edu/greco; Personal web page: http://www.invasiber.org/GarciaBerthou/; https://twitter.com/garciaberthou

Peer reviewed by: Felipe Morcillo Alonso. Associate Professor. Ecology Department. Complutense of Madrid University. email: [email protected]; www.felipemorcillo.com

Draft: December 2016Final version: 15/09/2017

mailto:[email protected]

https://twitter.com/garciaberthou

http://www.invasiber.org/GarciaBerthou/

http://www.udg.edu/greco

http://www.itis.gov/


As

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EU NON-NATIVE ORGANISM RISK ASSESSMENT SCHEME

Name of genus: Ameiurus Rafinesque, 1820 – bullheadsAmeiurus brunneus Jordan, 1877 – snail bullheadAmeiurus catus (Linnaeus, 1758) – white catfish, white bullheadAmeiurus melas (Rafinesque, 1820) – black bullhead,Ameiurus natalis (Lesueur, 1819) – yellow bullhead,Ameiurus nebulosus (Lesueur, 1819) – brown bullhead,Ameiurus platycephalus (Girard, 1859) – flat bullheadAmeiurus serracanthus (Yerger and Relyea, 1968) – spotted bullheadRetrieved [November, 11, 2016] from the Integrated Taxonomic Information System on-line database, http://www.itis.gov.

Author: Deputy Direction of Nature (Spanish Ministry of Agriculture and Fisheries, Food and Environment)Risk Assessment Area: EuropeDraft: 20 of DecemberFinal version: 31/01/2016

Peer reviewed by: Emili García-Berthou, Professor of Ecology. University of Girona. Institut of Aquatic Ecology. 17003 Girona, Catalonia, Spain. Tel.: +34 972 41 8369. http://www.udg.edu/greco; Personal web page: http://www.invasiber.org/GarciaBerthou/; https://twitter.com/garciaberthou

Peer reviewed by: Felipe Morcillo Alonso. Associate Professor. Ecology Department. Complutense of Madrid University. email: [email protected]; www.felipemorcillo.comDate of finalisation: 22/01/2017

Date of finalisation: 23/01/2016

mailto:[email protected]

https://twitter.com/garciaberthou

http://www.invasiber.org/GarciaBerthou/

http://www.udg.edu/greco



This Risk Assessment refers to genus Ameiurus and includes information about the most representative species, which have been introduced in Europe and established populations in at least one country. The characteristics of these species are representative for the genus Ameiurus.

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considered at the 5th Meeting of the Committee on Invasive Alien Species held in Brussels on 23 February 2016, this Risk Assessment was undertaken at genus level (Ameiurus spp). The most representative species, which have been introduced in Europe and its presence was recorded in at least one country, are described in detail (A. melas, A. nebulosus, A. natalis and A. catus). Three species of this genus (A. brunneus, A. platycephalus and A. serracanthus) are not described in detail in all sections of the Risk Assessment because information is missing. Lack of information about some Ameiurus species and their potential of invasion, and the precautionary principle lead us to consider the entire genus as having a certain potential of becoming invasive. Besides, the similar morphological appearance among species could lead to introduction of species that are invasive but not banned. Mandrak (2009), as cited in CABI, state that “the brown bullhead (A. nebulosus) is frequently confused with black bullhead A. melas (southern Canada, USA and parts of Mexico), yellow bullhead A. natalis (southern Canada, parts of USA), snail bullhead A. brunneus (southern USA), spotted bullhead A. serracanthus (southern USA) and flat bullhead A. platycephalus (southern USA)”. Barbieri et al. (2015) recognizes that identification errors between A. nebulosus and the closely related A. melas are possible. The unclear taxonomic status of both A. melas and A. nebulosus resulted in more doubts about the occurrence of these species in some countries as stated in Rutkayová et al (2013).

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EU CHAPPEAU

QUESTION RESPONSE

1. In how many EU member states has these species been recorded? List them.

There are records of A. melas, A. nebulosus, A. natalis and A. catus in Europe but there’s no information about the other three species. As there is some confusion with the identification of Ameiurus spp. (especially A. melas y A. nebulosus), in some cases their presence should be considered as “potencial”.

Ameiurus melas (Black bullhead):- Austria, Germany (Wiesner et al, 2010), )- Belgium (Holčík, 1991; Rutkayová et al., 2013)- Bulgaria (Uzunova y Zlatanova, 2007), Poland (Nowak, 2010),

Belgium, France, Italy, The Netherlands, UK (Holčík, 1991; Rutkayová et al., 2013), Portugal (Ribeiro et al, 2006), Spain (Elvira, 1984), )

- Croatia (Jelić et al, 2010), Slovenia (Piria et al, 2016), )- Czech Republic (Hartvich and Lusk, 2006), )- France (Holčík, 1991; Rutkayová et al., 2013)- Germany (Wiesner et al, 2010)- Hungary (Bódis et al, 2012)- Italy (Holčík, 1991; Rutkayová et al., 2013)- Poland (Nowak, 2010) (Holčík, 1991; Rutkayová et al., 2013)- Portugal (Ribeiro et al, 2006)- Romania (Wilhelm 1998; Gaviloaie and Falka 2006), Hungary (Bódis

et al, 2012), )- Slovakia (Koščo et al., 2004; Rutkayová et al., 2013), Denmark,

Finland (Secretariat of NOBANIS, 2012), Ireland (Minchin, 2007; CABI, 2015a) and possible Greece (Barbieri)

- Slovenia (Piria et al, 2016)

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- Spain (Elvira, 1984)- Sweden (Brockmark, 2015).)- The Netherlands (Holčík, 1991; Rutkayová et al., 2013)- UK (Holčík, 1991; Rutkayová et al., 2013).

Ameiurus nebulosus (Brown bullhead):- Belgium, Bulgaria, Netherlands, UK (Olenin et al., 2008); Austria,

Poland, Portugal, Spain, Italy, France, Germany, Czech Republic (Froese and Pauly, 2016); Croatia, Slovenia (Piria et al, 2016); Estonia, Ireland, Slovakia, Sweden (Secretariat of NOBANIS, 2012); Bulgaria, Finland, Romania ( (Wiesner et al., 2010; Kováč, 2015)

- Belgium (Olenin et al., 2008)- Bulgaria (Olenin et al., 2008, Global Invasive Species, 2016);

Luxembourg (Ries)- Croatia (Piria et al, 2014); Greece (Barbieri, 2015); 2016);- Czech Republic (Lusk et al, 2010))- Denmark, Hungary, Ireland, UK (CABI, 2015b (Mandrak, 2009;

Rutkayová ,et al.,2013)- Finland (FAO, 1997; Kottelat and Freyhof, 2007)- Germany (Scott and Crossman, 1973; Kottelat and Freyhof, 2007;

Nehring et al. 2010)- Greece (Barbieri et al, 2015)- Hungary (Mandrak, 2009); Rutkayová et al.,2013)- Italy (Amori et al., 1993; Kottelat and Freyhof, 2007)- Luxembourg (Ries et al, 2014)- Poland (Witkowski 2002)- Portugal (Kottelat and Freyhof, 2007)- Romania (Petrescu and Mag, 2006; Kováč, 2015)- Slovakia, (,Kovácˇ, 2015; Secretariat of NOBANIS, 2012)- Slovenia (Piria et al, 2016)- Spain (Froese and Pauly, 2016)- The Netherlands (Olenin et al., 2008)

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- UK (Olenin et al., 2008) (Mandrak, 2009); Rutkayová et al.,2013)There is a possibility that in some countries this species to be potententially present (especially where the source of information was a data base).

Ameiurus natalis (Yellow bullhead):)There are a number of reports of its introduction into Italy (Welcomme, 1988; HolcíkHolčík, 1991; Froese and Pauly, 2016). However, there is no reliable evidence for this. (CABI, 2009 (Godard, 2015a).

Ameiurus catus (White catfish)Confirmed presence in UK (Britton and Davies, 2006; Zieba, 2010), Poland (Nowak et al. 2008, 2010)).

There is no information about the introduction of any of the other three species of Ameiurus in Europe.

2. In how many EU member states has this species currently established populations? List them.

The unclear taxonomic status of both A. melas and A. nebulosus resulted in more doubts about the occurrence of these species in some countries (Rutkayová et al., 2013). Concerning the populations of A.

Related to Central and North Europe countries and according to Secretariat of NOBANIS (2012), Ameiurus melas and Ameirus nebulosos are classified in the Category 2 “Species with no detailed distribution map available.nebulosus, Species are established in the NOBANIS region either recently or has been for a longer period of time but are still expanding their introduced range. Risk profiles of category 2 species will be useful for countries to create their alarm list“.

Ameiurus melasThe black bullhead (Ameiurus melas) is known to have been introduced to most of the European countries as pointed-out in the first question, but established self-sustaining populations have been confirmed for: Belgium,

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The Netherlands (Verreycken et al. 2010), Austria (Wiesner et al. 2010), Germany (Wolter and Röhr, 2010), Czech Republic (Musil et al., 2008), UK (Wheeler, 1979; Copp et al, 2016), France (Copp, 1989; Cucherousset et al., 2006 ), Hungary (Bódis et al. 2012), Italy (Pedicillo et al. 2009), Poland (Nowak et al. 2010a, Nowak et al. , 2010b; Grabowska, 2010), Portugal (Gante and Santos 2002; Ribeiro et al. 2006), Romania (Wilhelm, 1998; Gaviloaie and Falka), Slovakia (Koščo et al., 2010), Croatia (Ćaleta et al., 2011), Slovenia (Piria et al, 2016), Spain (Miranda et al., 2010, De Miguel et al., 2014); Finland (Secretariat of NOBANIS, 2012), Ireland (Welcomme, 1988).A total of 18 countries of the 28 Member states. Ameiurus nebulosus:Kottelat and Freyhof (2007) indicated that it is established in Germany, Italy and Finland. Although (CABI, 2015b) mention that it is established in many European countries, A. nebulosus has often been mistaken for A. melas (See Rutkayová et al., 2013)

The distribution of A. melas has been described quite well. Its occurrence was confirmed in a large part of Europe, e.g. In Germany, the Czech Republic, Poland, Slovakia, Hungary, Romania. Concerning the populations of A. nebulosus, the situation is different. they have been recorded rather incoherently and mainly in central and eastern parts of Europe (up to Kuban and Volga drainages). Taking into account these facts, it can be assumed, that the real distribution of both species is possibly wider (Kottelat and Freyhof, 2007).

Taking into account the paragraphs above, we found references of establishment in the following countries. According to Savini et al. (2010) he fish has established feral populations in 19 European countries according to. We found references of this establishment for the next countries: Belgium (Verreycken et al, 2010), Bulgaria (Uzunova and Zlatanova, 2007), Finland (Food Agriculture Organization of the United Nations, 1997), Germany (Scott and Crossman, 1973), Hungary (Food Agriculture Organization of the

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http://www.cabi.org/isc/datasheet/94468#20077200237







United Nations, 1997), Italy (Amori et al., 1993), Poland (Food Agriculture Organization of the United Nations, 1997) ; Austria, Czech Republic, Denmark, France, Ireland, Netherlands, Romania, Slovakia (Global Invasive Species Database, 2016), Spain, Portugal (Kottelat and Freyhof, 2007), Greece (Barbieri, 2015). Elvira (2001) also points out Slovenia.

Ameiurus melas (Black bullhead):- Austria (Wiesner et al. 2010)- Belgium (Verreycken et al. 2010)- Croatia (Ćaleta et al., 2011)- Czech Republic (Musil et al., 2008)- France (Copp, 1989; Keith et al, 2011; Coop et al, 2005a;

Cucherousset et al., 2006a )- Germany (Arnold, 1990; Wolter and Röhr, 2010)- Hungary (Pintér, 1998; Bódis et al. 2012)- Italy (Bianco, 1998; Coop et al, 2005a; Pedicillo et al. 2008)- Poland (Nowak et al. 2010a, Nowak et al., 2010b; Grabowska, 2010)- Portugal (Almaça, 1995; Gante and Santos 2002; Ribeiro et al. 2006)- Romania (Wilhelm, 1998; Coop et al, 2005a; Gaviloaie and Falka,

2006)- Slovakia (Koščo et al., 2010)- Slovenia (Piria et al, 2016)- Spain (Coop et al, 2005a; Miranda et al., 2010, De Miguel et al.,

2014)- The Netherlands (Verreycken et al. 2010)- UK (Lever, 1977; Wheeler, 1979; Copp et al, 2016)

In the UK, there are some species that have been mentioned in one or more literature sources, but scrutiny of the evidence has either refuted, or raised sufficient doubt, that they were ever introduced in the UK (i.e. brown bullhead Ameiurus nebulosus (Britton et a.lal, 2010).

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Ameiurus natalis was reported as established in Italy (Elvira, 2001). This fact was confirmed only ten years after Gandolfi et al. (1991) had reported there were occurrences of the Yellow catfish in Italy. However, it does not seem to be established in Europe.

Ameiurus nebulosus (Brown bullhead):According to Savini et al. (2010), A. neboulosus has established feral populations in 19 European countries, although according to Irish and French reviewers this is not the case in Ireland and France. In conclusion, A. nebulosus established populations in the next 17 countries:

- Austria (Wiesner et al., 2010; Kováč, 2015; GLOBAL INVASIVE SPECIES DATABASE, 2016)

- Belgium (Verreycken et al, 2010)- Bulgaria (Uzunova and Zlatanova, 2007)- Czech Republic (Lusk et al, 2010)- Denmark (Carl and Møller, 2012)- Finland (FAO, 1997; Kottelat and Freyhof, 2007)- Germany (Kottelat and Freyhof, 2007; Nehring et al. 2010),- Greece (Barbieri et al., 2015)- Hungary (FAO, 1997, Kováč, 2015)- Italy (Amori et al., 1993; Kottelat and Freyhof, 2007)- Poland (FAO, 1997; Grabowska et al, 2010)- Portugal (Kottelat and Freyhof, 2007)- Romania (Petrescu and Mag, 2006; Kováč, 2015, GLOBAL

INVASIVE SPECIES DATABASE, 2016)- Slovakia (GLOBAL INVASIVE SPECIES DATABASE, 2016)- Slovenia (Elvira, 2001)- Spain (Kottelat and Freyhof, 2007).

The Netherlands (GLOBAL INVASIVE SPECIES DATABASE, 2016)

We asume that in some countries the misindentificaction of A. melas as A.

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nebulosus is possible (especially where the source of information is a database).

Ameiurus natalis (Yellow bullhead)Italy (Gandolfi et al. 1991; Elvira, 2001). However more recently this has been disputed due to a lack of reliable evidence (Kottelat and Frayhoff, 2007).

Ameiurus catus: (White catfish)There is no information available about the establishment of this species in UK and Poland (where it certainly has been introduced) or in other countries in Europe.

In conclusion the only species well established in Europe are A. melas y A. nebulosus.

3. In how many EU member states has this species shown signs of invasiveness? List them.

Ameiurus melas: (Black bullhead)- MostCroatia (Ćaleta et al., 2011)- France (Cucherousset et al., 2006a)- Germany (Nehring et al., 2015)- Hungary (Kosco et al, 2010; Kováč, 2015),- Italy (Amori et al, 1993; Novomeská et al, 2013)- Poland (Nowak et al, 2009)- Portugal (Garcia-de-Lomas et al., 2009; Miranda et al., 2010)- Romania (Kováč, 2015);- Slovakia (Kosco et al, 2010)- Slovenia (Piria et al, 2016)- Spain (Garcia-de-Lomas et al., 2009; Miranda et al., 2010)

The invasive nature of theA. melas is demonstrated in some countries, e. g France where it is among the few freshwater fish listed with a legal status of ‘invasive’ (Cucherousset et al., 2006a). The introduction of A. melas is

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reglementary forbidden (Article R432-5, Code de l’environnement, Ministère de la Transtion écologique et solidaire, 2017) as well as for the other Ameiurus species (Arrêté du 17/12/1985. Ministère de l’environnement de France, 1985).

Other European countries recognize the evidence of invasiveness in their waters, for instance: France, Poland, Spain, Portugal, Germany, Hungary, Slovakia, Czech Republic, Italy, Romania, Croatia Poland (Nowak et al, 2009), Spain and Slovenia.

Giving the characteristics of this species as described in Invasive Species Compendium of the Centre for Agriculture and Biosciences International (CABI) –(abundant in its native range; capable of securing and ingesting a wide range of food; gregarious; broad native range; high reproductive potential; longevity (4-5 years); highly adaptable to different environments; invasive in and outside its native range; a habitat generalist; tolerant of shade and poor quality waters) , this species can be considered invasive for all the countries where it has established populations.Portugal (Garcia-de-Lomas et al., 2009; Miranda et al., 2010), Germany (Nehring et al., 2015), Hungary and Slovakia (Kosco et al, 2010; Kováč, 2015), Romania (Kováč, 2015, Croatia (Ćaleta et al., 2011) and Slovenia (Piria et al, 2016),).

As mentioned before, those countries are:Belgium, The Netherlands (Verreycken et al. 2010), Austria (Wiesner et al. 2010), Germany (Wolter and Röhr 2010), Czech Republic (Musil et al. 2008), UK (Wheeler, 1979; Copp et al, 2016), France (Copp, 1989; Cucherousset et al., 2006 ), Hungary (Bódis et al. 2012), Italy (Pedicillo et al. 2009), Poland (Nowak et al. 2010a, Nowak et al. , 2010b; Grabowska, 2010), Portugal (Gante and Santos 2002; Ribeiro et al. 2006), Romania (Wilhelm, 1998; Gaviloaie and Falka), Slovakia (Koščo et al., 2010), Croatia (Ćaleta et al., 2011), Slovenia (Piria et al, 2016), Spain (Miranda et al., 2010, De Miguel et al., 2014); Finland (Secretariat of NOBANIS, 2012), and Ireland (Welcomme, 1988).

Novomeská et al. (2013), for example, studied A. melas from four European countries and consider it a species with “high invasive potential” due to characteristics such as “high reproductive potential,

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parental care, omnivory, aggressive behaviour and considerable tolerance to water pollution, turbidity, low oxygen concentration, elevated temperatures and a range of pH values”.

The black bullhead has been ranked in several European countries/regions as representing a high risk of being invasive, including Belgium, Iberia and the UK but medium risk in Finland. This invasiveness is demonstrated in some countries, e.g. France where it is among the few freshwater fish listed with a legal status of ‘invasive’. Whereas in the UK, only one of a few reported populations has been confirmed though the species has nonetheless been the subject of regulation since the 1980 (Copp et al., 2016). Related to UK, Ruiz-Navarro et al. (2015) conclude that there was little evidence to suggest that the inability of A. melas to be invasive in the UK was related to insufficient summer temperatures for their reproduction, with their integration into the food web at a relatively high trophic level suggesting that they also have access to ample food resources to facilitate their persistence. Thus, the continuation of their lag phase in the UK appears more related to their lack of dispersal opportunities from this single population in the wild than through ecological constraints. Correspondingly, should As consequence, individuals from this population should disperse in the future, then and invasive populations might subsequently develop.

Ameiurus nebulosus: (Brown bullhead):

According to NOBANIS, this species is recognized as invasive (including here that countries where it is considered potentially invasive) in at least 6 countries.

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Source: https://www.nobanis.org/species-info/?taxaId=8496

Conversely, according to Savini et al. (2010), the fish has established feral populations in 19 European countries.

- Kottelat and Freyhof (2007) indicated that it is established in Germany, Italy and Finland. Although CABI (2009) mentions that it is established in many European countries, A. nebulosus has often been mistaken for A. melas (See Rutkayová et al., 2012).Finland (Koli, 1990; Urho et al, 1995)

- Germany (Nehring et al., 2015)- Poland (Paduszek, 1996; Grabowska et. al, 2010)

The unclear taxonomic status of both A. melas and A. nebulosus resulted in more doubts about the occurrence of these species in some countries (Rutkayová et al., 2013).

Having all these possible mistakes in mind, we found references of establishment for the next 18 countries:Belgium (Verreycken et al., 2010), Bulgaria (Uzunova and Zlatanova,

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http://issg.org/database/species/distribution_display.asp?si=612&ri=18254&pc=*&sts=sss&status=Alien&lang=EN#Alien


2007Romania), Finland (Food Agriculture Organization of the United Nations, 1997), Germany (Scott and Crossman, 1973), Hungary (Food Agriculture Organization of the United Nations, 1997), Italy (Amori et al., 1993), Poland (Food Agriculture Organization of the United Nations, 1997), Austria, Czech Republic, Denmark, France, Ireland, Netherlands, Romania, Slovakia, (GLOBAL INVASIVE SPECIES DATABASE, 2016); Spain, Portugal (Kottelat and Freyhof, 2007); Greece (Barbieri, 2015).

- Giving the characteristics of this species (abundant in its native range; capable of securing and ingesting a wide range of food; fast growing; broad native range; high genetic variability; high reproductive potential; highly adaptable (Petrescu, 2006; Kováč, 2015)

- Italy (Kottelat and Freyhof, 2007)

Moreover, according to different environments; highly mobile locally; a habitat generalist; pioneering in disturbed areas; invasive outside its native range as described in http://www.cabi.org/isc/)Nehring et al. (2010), A. nebulosus it can be considered invasive for all the countries where it has established populationsis assigned to the “Invasive – Management List” in Germany.

There is no information about A. catus and A. natalis as invasive species in Europe, so it is possible that we are in time to prevent the invasion of the rest of the Ameiurus species. .4. In which EU Biogeographic areas could this species establish? Ameiurus melas is established in Continental, Atlantic, Mediterranean and

Boreal zones. It is casual in the Arctic zone. Once introduced, the dispersal rate of the species in the Central and North European countries was medium all these areas was medium. (Secretariat of NOBANIS, 2012).

Ameiurus nebulosus is established in Alpine, Continental, Atlantic and Boreal zones. Once

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http://www.cabi.org/isc/










http://issg.org/database/species/distribution_display.asp?si=612&ri=18254&pc=*&sts=sss&status=Alien&lang=EN#Alien


introduced, the dispersal rate the Central and North European countries was medium of the species in all these areas was medium. (Secretariat of NOBANIS, 2012).

Ameiurus natalis was reported as established populations in Italy (Elvira, 2001). This fact was confirmed only ten years after Gandolfi et al. (1991) had reported there were occurrences of the Yellow catfish in Italy. However, it does not seem to be currently established in Europe.

Ameiurus catus is present in Atlantic and continental regions.

It is to expect that the rest of the species of Ameiurus have the capacity to establish in the same biogeographic areas.According to Koppen-Giger climatic classification, temperatures in the USA States where these species are natives are similar to the temperatures of most of the European countries (mainly from central-south Europe).

Ameiurus melas tolerates a broad range of temperature (between 8 and 30ºC, Baensch and Riehl, 1991);Ameiurus nebulosus tolerates the broadest range of temperaturas: 0°C - 37°C (Beitinger and Bennett, 2000);Ameiurus natalis (Yellow bullhead); This eurythermal species rangs from southern Canada to northern Mexico.There are a number of reports of its introduction into Italy (Welcomme, 1988; Holčík, 1991; Gandolfi et al, 1991). It belongs to continental and warm temperate climat (prefferered temperatures between 5°C and 25°C; Aquatic Republic Network, 2017);Ameiurus catus (White catfish) requires water above 20 °C in summer (NatureServe, 2013). Recorded in UK (Britton and Davies, 2006);Ameiurus brunneus (Snail Bullhead).Introduced populations are established in Virginia, North Carolina and Georgia (USGS Nonindigenous Aquatic Species Database). Temperatures of these states are similar to mid-south Europe. Koppen-

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Giger classification within tipe C (warm climates);Ameiurus platycephalus (Flat bullhead)Distribution similar and a little bit more up north than the former species (NatureServe, 2013). No much difference with southern Europe temperatures.Ameiurus serracanthus (Spotted bullhead);Spotted bullheads are limited to the Chattahoochee River drainage in Alabama. Although they appear to be rare in state waters, their limited distribution may be due to insufficient sampling of preferred habitats.

In conclusion: A. brunneus, A. serracanthus and A. catus (that need warmer temperatures, could maybe establish only inMacaronesian biogeografical región andMediterranean biogeografical regionHowever, A. catus was cited in Atlantic Region, so it is possible that the range of establishment of these three species to be broader)

For the other four species we can affirm that they could establish in almost all European biogeographics areas:

The Continental biogeografical regionMediterranean biogeografical regionAlpine RegionAtlantic RegionBlack Sea RegionMacaronesian biogeografical regionPannonian RegionSteppic Region

5. In how many EU Member States could this species establish in the future [given current climate] (including those where it is already

Ameiurus melas:The species is already established in Bulgaria, Finland, Germany, Hungary,

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established)? List them. Italy, Poland, UK, Austria, Czech Republic, Denmark, France, Ireland, Netherlands, Romania, Slovakia, Spain; Portugal, and possible in Greece (where A. nebulosus was confirmed as established; Barbieri, 2015 recognizes that “identification errors between A. nebulosus and the closely related A. melas are possible”)

This species could establish in Luxembourg as a result of a natural spread process (Copp et al, 2016). In Sweden could also establish as a result of natural spread as it is already established in Finland. In Letonia, Estonia and Lithuania there are fewer possibilities to establish because it is not recorded in those countries and because of the boreal climate, but once introduced and due to climate warming, this is not impossible. There is no information about the existence of this species in Malta and Cyprus and it is not confirmed as established in Greece butThere is no information about the existence of this species in Malta and Cyprus. Probably the species of the genus Ameiurus would adapt to the climatic condition in these countries as the clime is alike to the zones where the species is established already. It seems that not only A. melas and A. nebulosus are able to establish self-sustaining populations in Europe, but we couldn´t find information for the rest of the species.

Ameiurus melas (Black bullhead):- Austria (Wiesner et al. 2010)- Belgium (Verreycken et al. 2010)- Croatia (Ćaleta et al., 2011)- Cyprus- Czech Republic (Musil et al., 2008)- France (Copp, 1989; Keith et al, 2011; Coop et al, 2005a;

Cucherousset et al., 2006a )- Germany (Arnold, 1990; Wolter and Röhr, 2010)- Greece (Barbieri et al., 2015)- Hungary (Pintér, 1998; Bódis et al. 2012)- Luxembourg (Copp et al, 2016)

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- Italy (Bianco, 1998; Coop et al, 2005a; Pedicillo et al. 2008)- Latvia- Lithuania- Malta- Poland (Nowak et al. 2010a, Nowak et al., 2010b)- Portugal (Almaça, 1995; Gante and Santos 2002; Ribeiro et al.

2006)- Romania (Wilhelm, 1998; Coop et al, 2005a; Gaviloaie and

Falka, 2006)- Slovakia (Koščo et al., 2010)- Slovenia (Piria et al, 2016)- Spain (Coop et al, 2005a; Miranda et al., 2010, De Miguel et

al., 2014)- The Netherlands (Verreycken et al. 2010)- UK (Lever, 1977; Wheeler, 1979; Copp et al, 2016)

If not already established, A. melas could still establish at least in Cyprus, Malta and Greece (Barbieri et al. (2015) recognizes that identification errors between A. nebulosus and A. melas are possible). At least in these contries the climate is very suitable.

The study developed by the Secretariat of NOBANIS in 2012 found that A.The study developed by the Secretariat of NOBANIS in 2012 found that A. melas did not establish population in Latvia, Lithuania or Estonia (countries with boreal climate) but A. nebulosus (with very similar requirements) was recorded in Estonia). In these countries, and also in Finland and Sweden, there are fewer possibilities to establish because it is not recorded in any of them and because of the boreal climate, but once introduced and due to climate warming, this is not impossible, as the only thing that seems to stop it is the water temperature.

Ameiurus nebulosus: (Brown bullhead)

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The speciesHaving in mind the possibility of misidentification of A. nebulosus,the countries where this is established in at least 18 countries: Finlandare:

- Austria (Wiesner et al., 2010; Kováč, 2015; GLOBAL INVASIVE SPECIES DATABASE, 2016)

- Belgium (Verreycken et al, 2010)- Bulgaria (Food Agriculture Organization of the United Nations,

1997Uzunova and Zlatanova, 2007), Bulgaria, Austria, Ireland, Poland, Portugal, Spain, Italy, France, Germany, Denmark, Netherlands, Belgium, Netherlands, Czech Republic (Froese et al.,)

- Czech Republic (GLOBAL INVASIVE SPECIES DATABASE, 2016); Ireland, )

- Denmark (Carl and Møller, 2012)- Finland (Secretariat of NOBANIS, 2012); FAO, 1997; Kottelat

and Freyhof, 2007)- Germany (Kottelat and Freyhof, 2007; Nehring et al. 2010),- Greece (Barbieri et al., 2015)

Hungary, Romania ( (FAO, 1997, Kováč, 2015)- Italy (Amori et al., 1993; Kottelat and Freyhof, 2007)- Poland (FAO, 1997; Grabowska et al, 2010)- Portugal (Kottelat and Freyhof, 2007)- Romania (Petrescu and Mag, 2006; Kováč, 2015, GLOBAL

INVASIVE SPECIES DATABASE, 2016); Greece (Barbieri, 2015). )

- In conclusion Slovakia (GLOBAL INVASIVE SPECIES DATABASE, 2016)

- Slovenia (Elvira, 2001)- Spain (Kottelat and Freyhof, 2007)

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- The Netherlands (GLOBAL INVASIVE SPECIES DATABASE, 2016).

A. nebulosus could establish anywhere in Europe, where it seems not to be established yet: in France, Malta, Cyprus, Croatia, Slovenia, Luxembourg, Latvia, Lithuania, Estonia, Sweden (similar climate to other countries where it is already established or because it is closed and easy to spread). A recently established population was located in 2012 in Lake Kerkini, probably introduced from Bulgaria (Barbieri, 2015).

Ameiurus natalis was reported as with established populations in Italy (Elvira, 2001). This fact was confirmed only ten years after Gandolfi et al. (1991) had reported there were occurrences of the Yellow catfish in Italy. However, it does not seem to be currently established in Europe; there is no information about his presence in other EU countries. This species could establish anywhere, at least in Mediterranean zone.

Ameiurus catus seems not to be established yet, but it´s presence was recently confirmed in Poland (Nowak, 2008) and and UK (Britton, 2006).It seems that not only A. melas and A. nebulosus are able to establish self-sustaining populations in Europe. Further establishment in Great Britain of A. nebulosus may be hindered by the temperate climate. This would inhibit reproduction, as it requires temperatures >more than 21° C (Kazyak and Raesby, 2003). However is considered invasive in Poland and Germany, countries with colder winters.

The North American catfish Ameiurus catus was recorded as introduced to Europe for the first time in Great Britain. An albino variety of 620 mm fork length and 4550 g was believed to have been an ornamental fish that was introduced subsequently into the wild (Britton and Davies, 2016).

We consider that the characteristics of the genus Ameiurus makes all the species desirable candidates to establish in Europe, once introduced.

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In the aquatic ecosystems the influence of zonal factors such as variations in temperature and precipitation is not very relevant, so that it is possible to speak of a remarkable homogeneity of the aquatic environment throughout the world. This fact supports the idea that Ameiurus spp. could establish anywhere is introduced.

The high scores achieved for brown bullhead Ameiurus nebulosus and black bullhead Ameiurus melas, two very robust and adaptable species characterised by high plasticity, were also obtained in most of the other RA areas where these species have been evaluated (i.e. Povz M. (2007b) Copp et al. 2009a; Almeida et al. 2013; Simonovic et al. 2013; Vilizzi & Copp 2013; Tarkan et al. 2014) – the exception here is Finland, where the colder climate relative to the UK and southern Europe may limit the species’ invasiveness (Puntila et al. 2013).

Ameiurus natalis (Yellow bullhead):- Croatia- France- Greece- Italy Slovenia- Portugal- Spain

We assume that A. natalis could establish at least in Mediterranean countries because the climate is suitable and, according to Gandolfi et al., (1991) and Elvira (2001) it is present in Italy.

6. In how many EU member states could this species become invasive in the future [given current climate] (where it is not already established)?

Related to Central and North Europe countries and according to Secretariat of NOBANIS (2012), Ameiurus melas and Ameirus nebulosus are classified in the Category 2 “Species with no detailed distribution map available. Species are established in the NOBANIS region either recently or has been for a longer period of time but are still expanding their introduced range. Risk profiles of category 2 species will be useful for countries to create their alarm list“.

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Ameiurus melas:Using an invasiveness screening tool for freshwater fishes, FISK (Copp et al. 2009), Ameiurus melas (Black bullhead):The black bullhead has been ranked in several European countries/regions as representing a high risk of being invasive, including Belgium, Spain, Portugal and the UK (Verbrugge et al., 2012; Almeida Real et al., 2013; Simonović et al., 2013; Tarkan et al., 2014; Piria et al. ., 2016),) but only medium risk in Finland (Puntila et al. ., 2013).

The species A. melas could become invasive in many of Europe’s rivers,Malta, Cyprus and possibly in Finlandia, Estonia, Lithuania and Latvia if established. climate changes will allow it.

The confidence of this prediction is higher in freshwater habitats, from small farm ponds to large lakes, creeks and rivers. They prefer soft bottoms, avoiding free flowing waters where water moves rapidly. They can tolerate poorly oxygenated, polluted, turbid, and high temperature waters.According to DAISIE, A. melas is declared as invasive in Belgium, Czech Republic, UK, Germany and Italy, but established populations in 19 European countries. Summarizing it may establish in the hole 28 EU Member states.

Ameiurus nebulosus: (Brown bullhead):According to NOBANIS, Ameiurus nebulosus is considered invasive in 6 countries included in NOBANIS Network (See question 3, above) but see above about taxonomic uncertainty.

In Scandinavian countries (Finland, Sweden)In south of Finland the species presents a medium-high risk of becoming invasive (Puntila, 2013). It seems that this species

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demonstrated a lower risk of becoming invasive than in countries of intermediate or lower latitudes. The same for theother countries with boreal climate (as Latvia, Estonia and Lithuania), but nevertheless the species already exists in Estonia.).

The rest of the countries where A. nebulosus has not established populations for now, the risk to become invasive depends on one hand of the future introductions (see Impact section) or if it spreads naturally (. Luxembourg, Croatia, Cyprus, Malta are countries with similar conditions to the countries where itthere are already established populations)..

A. natalis has all the characteristics of a successful invader (abundant in its native range; capable of securing and ingesting a wide range of food; broad native range; highly adaptable to different environments; highly mobile locally; habitat generalist), so it could establish in any country where A. melas and A. natalis (very similar species) are established.About A. catus there is less information because for now it has not established populations in Europe but it has the same characteristics of a successful invader of the other species of Ameiurus. So we can assume that it could become invasive in any country where introduced.

In conclusion for all Ameiurus species there is a major risk of becoming invasive in any European country once introduced.Ameiurus natalis (Yellow bullhead) and Ameiurus catus (White catfish)could become invasive in the future with more probability in mediterranean countries.

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SECTION A – Organism Information and Screening

Stage 1. Organism Information RESPONSE[chose one entry, delete all others]

COMMENT

1. Identify the organism. Is it clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?

Yes.This Risk Assessment refers to genus Ameiurus and includes information about the most representative species, species that have been introduced in Europe and established populations in at least one country.

The genus Ameiurus (Rafinesque, 1820) is part of Siluriformes Order (silures, catfishes) and Ictaluridae Family (Gill, 1861) – bullhead catfishes, North American freshwater catfishes.

From the Integrated Taxonomic Information System (http://www.itis.gov) Ameiurus spp. comprises the following species:

Ameiurus brunneus Jordan, 1877 – snail bullhead Ameiurus catus (Linnaeus, 1758) – white catfish, white bullhead Ameiurus melas (Rafinesque, 1820) – black bullhead Ameiurus natalis (Lesueur, 1819) – yellow bullhead Ameiurus nebulosus (Lesueur, 1819) – brown bullhead Ameiurus platycephalus (Girard, 1859) – flat bullhead Ameiurus serracanthus (Yerger and Relyea, 1968) – spotted

bullhead

Ictaluridae comprises eight genera (one extinct) and 67 species—51 living (12 with fossil records) and 16 extinct (Arce-H. et al., 2016). Monophyly of living Ictaluridae is well supported by molecular data analysed using parsimony and model-based methods. These analyses found further support for the monophyly of the genus Ameiurus. This genus is represented by16 species of which nine are fossils. Within Ameiurus, the basal split is between A. pectinatus, the oldest fossil species, and all other species. At the next higher node is a split between a clade with A. reticulatus plus A. natalis and a second clade with all the other species included in the analysis (Arce-H. et al., 2016).

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All bullhead species have an adipose fin between their dorsal and tail fins. This small fleshy fin lacks any hard, internal structures such as bone or cartilage. Bullheads have a rounded tail which will help distinguishing them from small channel catfish that have a forked tail. Bullheads have no scales, their bodies are covered with taste buds, and will be very slippery to handle. Finally, bullheads have a single, sharp spine in the dorsal and pectoral fins. Like other members of the Catfish Family, bullheads also have barbels (‘whiskers’) under their chin that help them locatedlocate food (Minnesota Department of Natural Resources, 2016).

Some species could be misidentified as Ictalurus (Rafinesque, 1820 – channel catfishes, forktail catfishes), a genus of the same family: Ictaluridae, (Gill, 1861). For instance I. punctatus (channel catfish) has been known to mate with brown bullhead (Ameiurus nebulosus), yellow bullhead (Ameiurus natalis), and black bullhead (Ameiurus melas), resulting in a variety of hybrid catfish (Florida Museum of Natural History. Online: https://www.flmnh.ufl.edu/fish/discover/species-profiles/ictalurus-punctatus/) , 2017).

With regard to the Ameiurus genus, the problem is with brown and black bullheads, given difficulties to identify Ameiurus species (Lenhardt et al, 2011).

Brown bullheads (Ameiurus nebulosus) are known to hybridize naturally with closely related black (Ameiurus melas) and yellow bullhead (Ameiurus natalis) species (Hunnicutt et al., 2005).

The species in the genus are sometimes very difficult to distinguish one from another (especially A. melas and A. nebulosus).

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One of the main distinguishing features separating Ameiurus melas and Ameiurus nebulosus is that the black bullhead is with rough or irregular small barbs on the trailing edge of the pectoral spines weak; whereas for the brown bullhead, the pectoral spike edge is with regular saw-like barbs. Other distinguishing features include the number of anal ray fins; the black bullhead has 15-21 anal ray fins, the brown bullhead 21-24. The colour pattern also varies with black bullhead being mainly solid and dark, with a white or yellow belly; faint pale yellow vertical bar at base of tail while the brown bullhead is usually mottled, but may be solid, generally yellow brown or grayish, belly usually cream or tan; no bar at base of tail (CABI, 2015aGodard, 2015b).

Ameiurus natalis is similar to the black bullhead, A. melas and brown bullhead, A. nebulosus. A. natalis can be distinguished from these species by its cream-white chin barbels. A. melas has dusky or black chin barbels, a rounded anal fin and fewer anal rays (19-23) and rakers on the first gill arch (15-21). A. nebulosus, is usually mottled on the side of the body, has dusky or black chin barbels and fewer anal rays (19-23) (CABI, 2009Godard, 2015a).

Confusion between species could be possible, so identification of other species in the genus as A. melas or A. nebulosus cannot be discarded (Lenhardt et al, 2011). A. nebulosus has often been mistaken for A. melas. The unclear taxonomic status of both A. melas and A. nebulosus resulted in more doubts about the occurrence of these species in some countries (Rutkayová et al., 2013).

The known common names of species of this genus in other European languages than English are the following:

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Brown bullheads (Ameiurus nebulosus) are known to hybridize naturally with closely related black (Ameiurus melas) and yellow bullhead (Ameiurus natalis) species (Hunnicutt et al., 2005).

The species in the same genus are sometimes very difficult to distinguish one from another (especially A. melas and A. nebulosus).

Ameiurus melas (Rafinesque,1820)EN: Black bullhead, DE: Schwarzer Katzenwels, FR: Poisson-chat, IT:Pesce gatto, ES:Pez gato negro.

Ameiurus nebulosus (Lesueur, 1819)EN: Brown bullhead; DE: Brauner Katzenwels; FR: Barbotte brune; ES: Pez gato; Barbú torito.

Ameiurus natalis (Lesueur, 1819)EN: Yellow bullhead; DE: Gelber Katzenwels; FR: Barbotte jaune; IT: Pesce gatto; ES: Cabeza de toro; Pez gato; Bagre torito amarillo.

Ameiurus catus (Linnaeus, 1758) – EN: White catfish, White bullhead; DE: Weiße Katzenwels; FR: Poisson-chat blanc; IT: Pesce gatto; ES: Barbú cabezón.

2. If not a single taxonomic entity, can it be redefined? (if necessary use the response box to re-define the organism and carry on)

NA

3. Does a relevant earlier risk assessment exist? (give details of any previous risk assessment)

NoYes Using an invasiveness screening tool The seven species of this genus were included in a rapid risk assessment approach that was developed in Australia to assess the potential impact of ornamental fish on the environment and other species if released into the wild. This report has

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assessed risk for freshwater fishes 447 ornamental fish species from the national grey list (Moore et al, 2010). The Department of Fisheries of the Governemnt of Western Australia (2013) included the 7 species of the genus Ameiurus in State’s Noxious Fish List. All of them have been hig punctuated a clsified as a “high risk” for invasion.

Ameiurus melas (Black bullhead):The black bullhead has been ranked in several European countries/regions as representing a “medium” or “high risk” of being invasive, including Belgium, Iberia, and using the UK, but mediumfish invasiveness scoring kit (FISK).

A.melas was classified as “high risk in” according to the study of Copp et al (2009).

Puntila et al (2013) concluded that the risk of invasion for south of Finland . This invasiveness is demonstrated in some countries, e.g. France where it is among the few freshwater fish listed with a legal status of ‘invasive’. Whereas in the UK, only one of a few reported populations has been confirmed, though the species has nonetheless been the subject of regulation since the 1980s. Data on that lone population in England is limited to morphology and an initial study of gonad development and dietary breadth (Ruiz-Navarro et al. 2015).“medium”.

A Risk Assessment for Ameiurus melas has been conducted in In Balkans Region and the result was that thethis species has a “medium-high risk” to become invasive (Simonović et al., 2013), Applying FISK v2 to).

Piria et al., (2016) categorize A. melas as “high risk” of being invasive for Croatia and Slovenia.

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The species is categorized as “high risk” of being invasive in the drainage basin of Lake Balaton (Hungary) (Ferincz et al., 2016).

In the Iberian Peninsula, Almeida et al. (2013) classified A. melasthe species as with “very high”risk of being invasive risk (maximum categorical score).

Tarkan et al. (2016) categorize the species as “high” risk for the frontier between Asia and Europe (Anatolia and Thrace).

Ameiurus melasnebulosus (Brown bullhead):The brown bullhead has been ranked in several European countries/regions as representing a “medium” or “high risk” of being invasive using the fish invasiveness scoring kit (FISK).

A.nebulosus was classified as “high risk” according to the study of Copp et al (2009).

Puntila et al (2013) concluded that the risk of invasion for south of Finland is “medium-high”.

Simonović et al. (2013) categorize the species as “high risk” to become invasive for the Balkans Region.A. nebulosus is categorized also as “high risk” of being invasive for Croatia and Ameiurus nebulosusSlovenia (Piria et al., 2016).

The species is categorized as “moderately high risk” of being invasive applying the Fish Invasiveness Screening Kit (FISK) in the drainage basin of Lake Balaton (Hungary). ) (Ferincz et al., 2016).

Verbrugge et al. (2012) carried out a comparison of available risk

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classifications for fish in various countries, where risk assessment protocols in force have been applied in their national context.

BE1 DE2 AT2 FISK/FI-ISK

UK4 IE5 CH6

Ameiurus nebulosus (Lesueur, 1819)

Watch list

Black list

Grey list

High risk4

n.r. Medium risk

n.a.

BE: Belgium, DE: Germany, AT: Austria, UK: United Kingdom, IE: Ireland, CH: Switzerland; n.a.: not applicable because protocol is limited to only one taxonomic group; n.r.: not reviewed. 1 Harmonia Database (2010); 2 Nehring et al. (2010) for fish species; 4 Non-native Species Secretariat (2010); 5 Invasive Species Ireland (2007); 6 Swiss Commission for Wild Plant Conservation (2008); (Verbrugge et al., 2012)

Verbrugge et al. (2012) indicates that risk classifications from one region cannot be applied to other regions without inserting a caveat.

Ameiurus nebulosus is categorized The species is categorized as “high risk” of being invasive in Greece applying FISK (Perdikaris et al., 2016).

Ameiurus melas is categorized as “high risk” and Ameiurus nebulosus as “high risk” of being invasive applying FISK in Croatia and Slovenia. (Piria et al., 2016).

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In Australia this genus (all the seven species: Ameiurus brunneus - Snail bullhead; Ameiurus catus - White catfish; Ameiurus melas - Black bullhead; Ameiurus natalis - Yellow bullhead; Ameiurus nebulosus - Brown bullhead; Ameiurus platycephalus - Flat bullhead; Ameiurus serracanthus - Spotted bullhead) is prohibited. For all these seven species there are heavy penalties for possessing, selling or importing live because they are included in Class 1 species (up to $5,500 for an individual or $11,000 for a corporation).http://www.dpi.nsw.gov.au/fishing/pests-diseases/noxious-fish-and-marine-vegetation

4. If there is an earlier risk assessment is it still entirely valid, or only partly valid?

NoYes In the study in Balkan region they only consider single countries.This present Risk Assessment pretends to actualize the information for all the EU countries about A. melas, and encompass the genus Ameiurus.The risk assessment mentioned before are all valid.

5. Where is the organism native? North America Ameiurus melas: (Black bullhead):Native to the Great Lakes, Hudson Bay, and Mississippi River basins in most of the eastern and central United States and adjacent southern Canada and northern Mexico, south to the Gulf Coast (Gulf Coast drainages from Mobile Bay in Georgia and Alabama to northern Mexico) (Page and Burr, 2011); apparently not native to the Atlantic Slope. (Fuller and Neilson, 2017a).

Native to Canada, USA and Mexico (CABI, 2015a).

Native Range: Great Lakes, Hudson Bay, and Mississippi River basins from New York to southern Saskatchewan and Montana, south to Gulf; Gulf Slope drainages from Mobile Bay, Georgia and Alabama, to northern Mexico. Apparently not native to Atlantic Slope (Fuller and Neilson, 2017a).

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Ameiurus nebulosus: (Brown bullhead):Native to North America: Atlantic and Gulf Slope drainages from Nova Scotia and New Brunswick in Canada to Mobile Bay in Alabama in USA, and St. Lawrence-Great Lakes, Hudson Bay and Mississippi River basins from Quebec west to Saskatchewan in Canada and south to Louisiana, USA (Froese and Pauly, 2016).

Northamerica (CABI, 2015b)

Native Range: Atlantic and Gulf Slope drainages from Nova Scotia and New Brunswick to Mobile Bay, Alabama, and St. Lawrence Great Lakes, Hudson Bay, and Mississippi River basins from Quebec west to southeastern Saskatchewan, and south to Louisiana. This species may have been originally absent from all or part of the Gulf Coast west of the Apalachicola and east of the Mississippi River. This speculation is based on the very spotted distribution of the species both in panhandle Florida and Alabama and the fact that it appears to be largely confined to reservoirs in Alabama. In its native range in peninsular Florida it is found primarily in larger bodies of water; Whereas, on the Atlantic Slope in Florida, this species is found in both streams and sloughs (Fuller and Neilson, 2017b).

Ameiurus natalis: (Yellow bullhead):Native throughout most of the eastern and central USA and south eastern Canada, maybe New Hampshire (where has been recorded as native (Scarola, 1973; Scott and Crossman, 1973) but also as introduced (U.S. Geological Survey, 2015).

Ameiurus natalis, a species of bullhead catfish, is native throughout most of the eastern and central USA and south eastern Canada (CABI, 2009)

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Native Range: Atlantic and Gulf Slope drainages from New York to northern Mexico, and St. Lawrence Great Lakes and Mississippi River basins from southern Quebec west to central North Dakota, and south to Gulf (Fuller and Neilson, 2017c).

Ameiurus catus: (White catfish): Atlantic and Gulf Slope drainages from lower Hudson River, New York, to Apalachicola basin in Florida, Georgia, and Alabama; south in peninsular Florida to Peace River drainage (modified from Page and Burr 1991).

Native Range: Atlantic and Gulf Slope drainages from lower Hudson River, New York, to Apalachicola basin in Florida, Georgia, and Alabama; South in peninsular Florida to Peace River drainage (Fuller and Neilson, 2017c).

Ameiurus brunneus (Snail Bullhead):Native to Atlantic Slope from the Pee Dee River drainage, southern Virginia, south to Altamaha River drainage, Georgia, and middle St. Johns River drainage, Florida; Gulf Slope in Apalachicola River basin, Georgia, Alabama, and Florida (Page and Burr 1991; Fuller, 2017a).

Ameiurus plathycephalus (Flat Bullhead):Native to Atlantic Piedmont and Coastal Plain from Roanoke River drainage, Virginia, to Altamaha River drainage, Georgia (Page and Burr 1991; Fuller, 2017b).

Ameiurus serracanthus (Spotted Bullhead):The spotted bullhead is known from the Coastal Plain province in the Suwannee, Ochlockonee, Apalachicola and St. Andrews Bay drainages in Alabama, Florida and Georgia, associated with the limestone regions of these states (Page and Burr, 1991).

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6. What is the global distribution of the organism (excluding Europe)?

North and South America, Canada, EuropaEurope, Asia, Oceania, Pacific Islands

Ameiurus melas: (Black bullhead):Introduced widely outside the native range. (Rose, 2006). Apart of Europe, it has been introduced also in Chile (Welcomme, 1988; Froese and Pauly, 2004), Mexico (Page and Burr, 1991; Froese and Pauly, 2004) and many states in the USA.

Ameiurus nebulosus: (Brown bullhead):It has been introduced outside of its native range in North America to other areas of North America, Europe, Asia and Pacific islands (i.e. New Zealand, Hawaii). Also Chile, Iran and Turkey (Salvador, 2015; Froese and Pauly, 2016).

Ameiurus natalis: (Yellow bullhead):Introduced into at least 14 states in the USA outside of its native range (Fuller et al., 1999), in addition to southwestern British Columbia (Hanke et al., 2006). Also it has been introduced in Mexico, as an aquaculture species (FAO, 1997).

Ameiurus catus (White catfish). It was introduced in many states in USA (USGS, 2016), in Puerto Rico (Erdsman, 1984) and Mexico (Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, 2016).

7. What is the distribution of the organism in Europe?

See answer to question 1nº1 of EU CHAPEAU.

The unclear taxonomic status of both A. melas and A. nebulosus resulted in more doubts about the occurrence of these species in some countries (Rutkayová et al., 2013). Except for Estonia, Latvia, Malta and Cyprus (no information), in every European country at least one species (A. melas, A. nebulosus, A. natalis or A. catus), has been introduced.

Ameiurus melas: (Black bullhead). Widely distributed across Europe: (Austria, GermanyBelgium, Bulgaria, Poland, Belgium, France, Italy,

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The Netherlands, UK, Portugal, Spain, Croatia, Slovenia, Czech Republic, France, Germany, Greece, Hungary, Italy, Poland, Portugal, Romania, Hungary, Slovakia, Denmark, Finland, Ireland,Slovenia, Spain, Sweden ,The Netherlands and UK, also possible in Greece, Balkan countries, Albania and Turkey.

Ameiurus nebulosus:

Ameiurus nebulosus (Brown bullhead):Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Germany, Greece, Hungary, Italy, Luxembourg, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, The Netherlands and UK.

Kottelat and Freyhof (2007) indicated that it is established in Germany, Italy and Finland. Although (CABI, 2015bMandrak, 2009) mention that it is established in many European countries, A. nebulosus has often been mistaken for A. melas (See Rutkayová et al., 2012). The unclear taxonomic status of both A. melas and A. nebulosus resulted in more doubts about the occurrence of these species in some countries (Rutkayová et al., 2013).

Conversely, Some authors consider it widely distributed across Europe: from the Iberian Peninsula till the European part of Russia, Switzerand, TurkiaTurkey, Balkan countries and more recently in Greece (Barbieri, et al., 2015)

Having in mind the possible mistakes already done with this species, we found bibliography about its record in Belgium, Bulgaria, Netherlands, UK (Olenin et al., 2008); Austria, Poland, Portugal, Spain, Italy, France, Germany, Denmark, The Netherlands, Belgium, Germany; Denmark, Hungary, Czech Republic (Froese and Pauly,

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2016); Croatia, Slovenia (Piria et al, 2016); Estonia, Ireland, Slovakia, Sweden (Secretariat of NOBANIS, 2012); Bulgaria, Finland, Romania (GLOBAL INVASIVE SPECIES, 2016); Luxembourg (Ries et al, 2014); Greece (Barbieri, 2015).

Ameiurus natalis: (Yellow bullhead). There are a number of reports of its introduction into Italy (Welcomme, 1988; HolcíkHolčík, 1991). Gandolfi et al, 1991) also informed about the occurrence of the yellow catfish in Italy. Thirteen years later the species is confirmed as established in Italy (Elvira, 2001).

Ameiurus catus (White catfish). UK (Britton and Davies, 2006); Poland (Nowak et al. 2008, 2010).). There is no information available about his spread to other countries, but confusion between species could beis possible, so identification of other species in the genus as A. melas or A.nebulosus cannot be discarded.Except for Latvia, Letonia (not confirmed), Malta and Cyprus (no information), in every European country at least one species of Ameiurus has been introduced.

8. Is the organism known to be invasive (i.e. to threaten organisms, habitats or ecosystems) anywhere in the world?

Yes Ameiurus melas and A. nebulosus are recognized as succesfull invaders in Europe (Invasive Species Specialist Group, 2009). Ameirus nebulosus is included in the watch list of Belgium (Branquart, 2016).

Aquatic macroinvertebrates (mainly Chironomidae) dominated the black bullhead´s diet in all size-classes and sites, irrespective of natural riverine or artificial lentic habitats. Secondary prey items were responsible for the observed between-sites (microcrustaceans in artificial lentic habitat; oligochaeta and caddisfly larvae in natural riverine habitats) and ontogenetic diet differences (from microcrustaceans to larger prey). It consumed plant material, terrestrial prey and co-occurring fish species (native or exotic) and thus they

38


could be considered as generalist or opportunistic, foraging on the most abundant and available prey. It can negatively affect native (Iberian) ichthyofauna throughout direct predation and competition (Leunda et al., 2008).

The fishery in North London had succumbed to a highly efficient invader, A. melas, and the local angling club had lost one of their best fisheries.(https://marinescience.blog.gov.uk/2015/08/07/eradicating-black-bullhead-catfish/).

The high flexibility in the life history of the black bullhead as demonstrated by its non-native populations, as well as its extreme tolerance and capability to live in systems with poor water quality, suggests that this species has a high potential to invade new areas and establish viable populations. (Novomeska and Kovac, 2009).

The great growth and life-history plasticity of black bullhead affords the species great potential to invade and establish viable populations in new areas. A species tolerant of pollutants, low dissolved oxygen (3.0 mg L-1), and elevated water temperatures (up to 35 ºC) the black bullhead also has a specialized, nest-guarding, reproductive strategy. Many of the introduced fishes in Europe are nest-guarders, which suggests that black bullhead has the potential to be highly invasive and exert impacts to ecosystem function through increased turbidity (Copp et al., 2016)

Ameiurus nebulosus is a generalist omnivore, feeding mostly at night and eating benthic organisms that occur frequently within freshwaters: waste, molluscs, immature insects, terrestrial insects, leeches, crustaceans, worms, algae, plant material, fishes and fish eggs (Scott

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https://marinescience.blog.gov.uk/2015/08/07/eradicating-black-bullhead-catfish/



and Crossman, 1973). Young (30-60 mm total length) prefer chironomid larvae, ostracods, amphipods, mayflies and other small aquatic invertebrates (Scott and Crossman, 1973).

This omnivorous fish species can form very dense populations and is able to dominate freshwater fish communities. Diet of large-sized bullheads has been found to consist almost exclusively of juvenile fishes. (Anseeuw et al., 2007).

For those reasons A. nebulosus is considered a pest in Poland, and fisheries legislation forbids release of this species into the wild. (Nowak et al, 2010).

The ecological effects of A. melas seem potentially close to the A. nebulosus (Nowak et al, 2010).

Several countries (Switzerland (Wittenberg, 2005); Poland (FAO, 1997); Chile (Welcomme, 1988)) report adverse effects on native fish communities following its establishment.(http://www.cabi.org/isc/datasheet/94468)

Related to the distribution of brown bullhead, its decline in some European countries, e.g. Belgium, Czech Republic and Poland, has coincided with an increase in the distribution and abundance of black bullhead in Central and Eastern Europe; these contrasting patterns have led to suggestions that black bullhead is displacing brown bullhead. However, the two species have overlapping native distributions so this may simply be coincidental. However, further study is needed to determine whether or not this is artifact or indicative of black bullhead displacing brown bullhead (Copp et al., 2016)

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http://www.cabi.org/isc/datasheet/94468


Ameiurus natalis is known to eat minnows, crayfish, insects, and larvae of insects, aquatic invertebrates, worms and more aquatic vegetation (macroalgae) then the other bullheads.The yellow bullhead was largely introduced in other North American countries where it is not-native. At least one country reports adverse ecological impact after introduction of Ameiurus natalis in North America (Froese and Pauly, 2016)

Ameiurus catusWhite catfish is apparently responsible for the disappearance of Sacramento perch Archoplites interruptus in Thurston Lake, California (McCarraher and Gregory, 1970).Following the literature data, ictalurids are nocturnal zoophagophores, consuming all animals in the water column whose size allows the species to consume them. Besides invertebrates, among which insect larvae are preferred, ictalurids feed on molluscs and fishes, as well as algae, plant material and terrestrial invertebrates (Scott and Crossman, 1973; Brylinski and Chybowski, 2000; Kottelat and Freyhof, 2007; Leunda et al., 2008; Ruiz-Navarro et al. 2014). Ameiurus species are predators of small fishes and larvae that show identical microhabitat requirements (Leunda et al., 2008).

Moreover, theythe bullheads are vectors of alien parasites (Scholz and Cappellaro, 1993; Uzunova and Zlatanova, 2007; Sheath et al., 2015).

In resume the bullheads could negatively affect native ichthyofauna throughout direct predation and competition (Leunda et al, 2008).

In Australia this genus is prohibited. For all these seven species there are heavy penalties for possessing, selling or importing live because they are included in Class 1 species (noxious listing prohibits sale and possession) (up to $5,500 for an individual or $11,000 for a

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corporation) (Department of Primary Industries, New South Wales Gorvenment, 2017).

In Japan the entire genus is regulated in the Invasive Alien Species Act and a detailed investigation by the Japan Government is required before importation (Nature Convervation Bureau, Ministry of the Environment of Japan, 2011).

Ameiurus melas and A. nebulosus are recognized as succesful invaders in Europe (Invasive Species Specialist Group, 2009).

Related to Central and North Europe countries and according to Secretariat of NOBANIS (2012), Ameiurus melas and A. nebulosus are classified in the Category 2 “Species with no detailed distribution map available. Species are established in the NOBANIS region either recently or has been for a longer period of time but are still expanding their introduced range. Risk profiles of category 2 species will be useful for countries to create their alarm list“.

The characteristics of a successful invader, well demonstrated for A. melas and A. nebulosus could be met in the case of other species of Ameiurus genus.

Collier and Grainger (2015) identify A. nebulosus with a high overall risk in New Zealand.

In Japan is an uncategorized alien species and needs a detailed investigation by the Japan Government before importation (https://www.env.go.jp/nature/intro/4document/files/r_yunyu2.9_e.pdf).

Ameiurus melas (Black bullhead):Giving the characteristics of this species as described in Invasive

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https://www.env.go.jp/nature/intro/4document/files/r_yunyu2.9_e.pdf


Species Compendium of the Centre for Agriculture and Biosciences International (Godard, 2015b): abundant in its native range; capable of securing and ingesting a wide range of food; gregarious; broad native range; high reproductive potential; longevity (4-5 years); highly adaptable to different environments; invasive in and outside its native range; a habitat generalist; tolerant of shade and poor quality waters), this species has a medium or high degree of invasiveness for all the countries where it has established populations.

Ameiurus nebulosus (Brown bullhead):Giving the characteristics of this species (abundant in its native range; capable of securing and ingesting a wide range of food; fast growing; broad native range; high genetic variability; high reproductive potential; highly adaptable to different environments; tolerant of a broad range of temperaturas (0-30ºC); highly mobile locally; a habitat generalist; pioneering in disturbed areas; invasive outside its native range as described in Mandrak (2009) it can be considered potentially invasive for all the countries where it has established populations.

A. nebulosus is considered a pest in Poland, and fisheries legislation forbids release of this species into the wild (Nowak et al, 2010, Grabowska et al, 2010).

Several countries (Switzerland (Wittenberg, 2005); Poland (FAO, 1997; Grabowska et al, 2010); Chile (Welcomme, 1988) report adverse effects on native fish communities following its establishment.

Nonnative predators, including Brown Bullhead, have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Fuller and Neilson, 2017b).According to Verbrugge et al. (2012), A. nebulosus is recorded in the Watch list in Belgium (Harmonia Database, 2010), in the Black list in

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Germany (Schwarze Liste invasiver Arten) and in the Grey list in Austria (Schwarze Liste invasiver Arten). Moreover it was classified as medium risk in Invasive Species Ireland.

Ameiurus natalis (Yellow bullhead):The yellow bullhead was largely introduced in other North American countries where it is not-native. At least one country reports adverse ecological impact after introduction of Ameiurus natalis in North America (Froese and Pauly, 2016).Ameiurus catus (White catfish):White catfish is apparently responsible for the disappearance of Sacramento perch Archoplites interruptus in Thurston Lake, California (Fuller and Neilson, 2017).

9. Describe any known socio-economic benefits of the organism in the risk assessment area.

Fishing – low benefits Low benefits in sport fishing and very low in pet trade.

As they are so tolerant to poor water conditions, the bullheadsBullheads aren’t between the species that historically dominated the European aquaculture and that nowadays they don’t represent an alternative to the rainbow trout and carp farming. At the same time, in recent years, in the complex panorama of European inland aquaculture, the appearance of new exotic species for culture purposes should be considered with concern (Turchini et al., 2008), having said that, Bianco and Ketmaier (2016) recognise that Ameiurus melas and Ameiurus nebulosus are used in aquaculture in Italy.

Human activities can have a negative effect on fish. Pollution and habitat destruction are major problems for a number of fishes. Catfishes (particularly bullheads) have an advantage, an unusual ability to adapt to many adverse water quality situations that can kill other fish. However, there is a negative side to this: while the bullheads are able to survive in sometimes polluted water, they may accumulate the

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pollutants in their bodies. Therefore, in some waters, bullheads contain elevated levels of contaminants. The New York State Department of Health has issued an advisory with recommendations for limiting consumption of contaminated fish. So it seems that they no longer represent an economic value.The advisory is updated annually and can be found in the Regulations Guide issued with every fishing license. The Department of Environmental Conservation has programs to control discharges of pollutants to waters and to clean up the toxics that are already there. Progress is being made and, in certain waters, the amounts of toxics found in many fish are decreasing. But water pollution control programs will have to continue to ensure all fish from New York State waters are safe to eat (Department of Environmental Conservation. New York State, 2017).

Low benefits in sport fishing and very low in pet trade.

Ameiurus melas: (Black bullhead (Ameiurus melas formerly Ictalurus melas), a) is an important species which is very close to brown bullhead (Ameiurus nebulosus), is farmed in Italy in open farms (production in Italy for 2010 estimated in 250 tons) (EFSA, 2011for aquaculture in central Italy (Sicuro et. al, 2016).The yearly European aquaculture production and value of Black bullhead Ameiurus melas (average of 2000–2004) is in the ninth position (473.4 tons; 1,770.7 thousands US$; 3.74 US$ kg–1) (Turchini et al, 2008).

Ameiurus nebulosus: (Brown bullhead):Economic benefits from aquaculture occur primarily within Chile, China, Bulgaria and Belarus (Welcomme, 1988; Tan and Tong, 1989; Reshetnikov et al., 1997; Mikhov, 2000), although the magnitude of these benefits remains uncertain. Introduced populations of A.

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nebulosus to Europe and some Pacific islands originally provided social benefits as sportfish (Welcomme, 1988), but their current social value as sportfish within their introduced range is low and has poor economic value. Within their native range, the species may be held within zoos or public aquariums (CABI, 2015b).

Ameiurus nebulosus is popular in some areas as a gamefish. Reportedly a good eating fish, especially when smoked (Global Invasive Species, 2006Mandrak, 2009).

AmeirusAmeiurus melas and AmeirusAmeiurus nebulosus is only a main speciesare used in aquaculture in Italy, and not in Slovenia or Croatia (Bianco and Ketmaier, 2016).

Ameiurus natalis: (Yellow bullhead). This species is of low economic importance as a food fish, stocking into ponds, aquaculture and commercial aquarium trade. A. natalis is extensively used as a laboratory animal for toxic chemicals and medical experiments.Ameiurus natalis is considered good to eat and may be sought by some fishermen. It is of low economic importance as a food fish, stocking into ponds, aquaculture and commercial aquarium trade. A. natalis is extensively used as a laboratory animal for toxic chemicals and medical experiments (CABI, 2009).

Godard, 2015a). The yearly European aquaculture production and value of Black bullhead Ameiurus melas (average of 2000–2004) is in the ninth position (473.4 tons; 1,770.7 thousands US$; 3.74 US$ kg–1) (Turchini et al, 2008).

In European inland aquaculture, there are American native finfish species supporting a relatively good production (1,292 tons/year in the

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5-year period 2000–2004) (Turchini et al., 2008).

The impacts of aquaculture on biodiversity and particularly the utilization of alien species for culture purposes are of current and increasing concern, and the consequences of decreasing or changing biodiversity are well known to be potentially devastating. It has been speculated that the presence of alien fish can be a reliable indicator of river health and therefore the wellbeing of European inland waters can be considered to be at high risk (Turchini et al., 2008).

Variable results have been accomplished by species introductions, depending on the species and geographic area. Only a few finfish species are generally recognized as beneficial from a socio-economic viewpoint, usually by improving fishing or aquaculture opportunities. In natural waters, the introductions have resulted in many cases in economically profitable fisheries, although most introductions have failed or led to unwanted consequences in the form of reduced or collapsed native fish stocks (Turchini et al., 2008).

Bullfish are not between the species that historically dominated the European aquaculture and that nowadays they don’t represent an alternative to the almost unprofitable rainbow trout and carp farming.At the same time, in recent years, in the complex panorama of European inland aquaculture, the appearance of new exotic species for culture purposes should be considered with concern (Turchini et al., 2008).

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SECTION B – Detailed assessment

PROBABILITY OF ENTRY

Important instructions: Entry is the introduction of an organism into Europe. Not to be confused with spread, the movement of an organism within Europe. For organisms which are already present in Europe, only complete the entry section for current active pathways of entry or if relevant

potential future pathways. The entry section need not be completed for organisms which have entered in the past and have no current pathways of entry.

QUESTION RESPONSE[chose one entry, delete all others]

CONFIDENCE[chose one entry, delete all others]

COMMENT

1.1. How many active pathways are relevant to the potential entry of this organism?

(If there are no active pathways or potential future pathways respond N/A and move to the Establishment section)

Aquaculture, fisheries …,ornamental

lowmedium It seems that for A. melas and A. nebulosus which are widespread, and are already present in Europe, not active introductory pathways are still relevant. However a summary of pathway history for the four species introduced in Europe is included here.

For the other 5 species included in this genus further questions (1.2-1.11) are answered completing all the questions for the list of relevant pathways through which the organisms could enter.

The introduction of freshwater animal alien species, mainly fishes, intensified after the mid 19th century under the promotion in Europe by some “acclimatization societies”. In Russia, for instance, almost 250 introductions that included 35

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fish and 13 invertebrate species were annually conducted by the Russian Society of Acclimatisation since 1857. Similarly, the Society for Acclimatisation of Animals, Birds, Fishes, Insects and Vegetables, established in 1860 in Britain, was responsible for the majority of the introductions from continental Europe (DAISIE, 2009).

Ameiurus melas (Black bullhead). Introductions of black bullhead have historically been for either aquaculture, or recreational fishing or as an ornamental species. In(Wilhelm, 1998. In: Musil et al, 2008). Black bullhead, sometimes misidentified as brown bullhead, was introduced to some countries (e.g. France, Romania, Spain, Italy) in the late 19th/early 20th century, but only began to appear in other European waters, the dispersal mechanism is not clear but countries in the 1980s (Pintér, 1998: Elvira and Almodóvar, 2001).In Italy, the introduction of alien fishes, in particular North American species (e.g., M. dolomieu, Ameiurus melas, Ictalurus punctatus, and Salvelinus namaycush), began in the mid-19th century with most being introduced during 1897–1898 by two centers of ichthyology based in Brescia and Rome (DAISIE, 2009).A. melas was historically introduced in 1871 in France when some individuals were imported and during the 20th spread could be as a result of accidental and illegal introductions or natural dispersion between countries via watercourses

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(CABI, 2015a)over all the country (Keith et al., 2011).

A.Ameiurus nebulosus (Brown bullhead) was likely spread primarilyintroduced for recreational angling opportunities. Its spreadJonsson and Jonsson, (2016) assert that A.nebulosus have been dispersed beyond their native ranges because they are interesting in aquaculture.Introduction via fisheries (angling/sport purposes) and aquaculture are the dominant long-distance (national; international) vectors. Intentional introductions by fisheries managers may result in long-distance travel events via stocking from source populations. Aquaculture introductions may have similar magnitudes of spread. Unauthorized introductions by anglers also has been undoubtedly facilitated by its abilitythe potential to survive low oxygen concentrations for prolonged periods. Its establishment, once introduced, was likely assisted by its generalist, omnivore dietcontribute to local, national or international events but may be constrained by the effectiveness of certain legal restrictions that prohibit import of live organisms across borders (Mandrak, 2009).In Germany, fish importations, pioneered by Max von dem Borne (1826–1894), commenced in 1882 with feeding aided, even in turbidthe introduction of North American species (e.g., Salvelinus fontinalis, Ameiurus nebulosus, and Micropterus dolomieu) (DAISIE, 2009).

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Ameiurus natalis (Yellow bullhead) was intentionally introduced in new waterways by several pathways, including releases from aquariums and intentional stocking in open waters, by its chin barbels (CABI, 2015b) for food and game fish (Godard, 2015a).

Results based on the morphological characters confirmed the occurrence of A. melas for the first time in the Czech republic freshwaters. In terms of A. melas origin (in case of the Czech Republic), the most probable explanation for its finding in the Lužnice River floodplain might be natural spread of individuals from pond aquaculture, via e.g.Ameiurus catus (White catfish) was first introduced as intentional stocking for sport and food. It was recorded as introduced to Europe for the first time in Great Britain. An albino variety of 620 mm fork length and 4550 g was believed to have been an ornamental fish that was introduced subsequently into the wild (Britton and Davies, 2016). pond connecting canals. Thus, it seems likely that A. melas was accidentally imported amongst carp (Cyprinus carpio L.) or tench (Tinca tinca L.) from countries where it already widely occurs, such as Hungary or Romania (Wilhelm, 1998. In: Musil et al, 2008).

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1.2. List relevant pathways through which the organism could enter. Where possible give detail about the specific origins and end points of the pathways.

For each pathway answer questions 1.3 to 1.10 (copy and paste additional rows at the end of this section as necessary).

[ornamental fish; contaminated stocks; intentional stocking for sport fishing and food]

medium We have no official information about active pathways, but even if they are not often sold, bullheads do sometimes make their way into stores, especially those specialized in ornamental pond stocking. The Black, Brown, and Yellow Bullheads seem to be more common1.

Taking into account the confirmed presence in the EU of 4 of the 7 species of this genus, only relevant pathways through which Ameiurus brunneus, A. platycephalus and A. serracanthus could enter are listed further.

With the most stringent controls in the EU on the release of fishing species, game fish is not to be considered as a very possible pathway.

The risk assessment covers the possible ornamental trade not well controlled, via internet or otherwise.

Unintentional introductions through stocks with contaminated fish are also possible.

Pathway name: [ornamental uses]

1.3. Is entry along this pathway intentional (e.g. the organism is imported for trade) or accidental (the organism is a contaminant of imported goods)?

(If intentional, only answer questions 1.4, 1.9, 1.10, 1.11)

intentional medium There is a risk of entry as ornamental or aquaria trade not well controlled, via internet or otherwise.See the report of the department of agriculture, fisheries and forestry of the Australian Governement (Moore and al., 2010).

1 http://thenativetank.tumblr.com/post/127891892549/bullhead-catfish-of-the-genus-ameiurus-in-between

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1.4. How likely is it that large numbers of the organism will travel along this pathway from the point(s) of origin over the course of one year?

Subnote: In your comment discuss how likely the organism is to get onto the pathway in the first place.

moderately likely low For the species that have been already well established, a large number in such a short time, it is unlikely to entry.A. brunneus, A. platycephalus and A. serracanthus do not seem to be reported in the aquarium hobby (Aquatic Republic Network, 2017), However there are possibilities to be found inadvertently within the aquarium trade. It is well known that this sector depends on the trends in aquaristiscs. (https://www.aquariacentral.com/forums/threads/how-many-different-fish-do-you-have.184473/page-4#post-1852364)

1.9. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host?

likely high Release from ornamental aquariums or ponds are one of the well-known pathways of entry for other invasive alien species present in Europe, especially for species that have no tradition in aquaria and once they became adults, do not meet expected behavior e This could be possible with A. brunneus, A. platycephalus and A. serracanthus if they were used like ornamental fishes.

1.10. Estimate the overall likelihood of entry into Europe based on this pathway?

moderately likely medium Currently, these species are not very common in the ornamental trade in Europe but they could be in the future. Moreover, these species can be bought online. Then, this pathway of entry cannot be neglected.

Pathway name: [contaminated stocks of other fish species]


accidental medium Controls are stricter everyday in the EU, but there is a real difficulty in identification (Mandrak, 2009; Rutkayová et al 2013). Confusion and inadvertent entry, especially if they come when alevines or in

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big stocks of fishes, are possible. This pledge in favour of banning the entire genus.This situation has occurred with other species, for example Pseudorasbora parva contaminating Tinca tinca.



moderately likely medium A large number of fish is not very likely to entry accidentally over the course of one year, but in the past some invasions occurred because of inadvertent entry, for example Pseudorasbora parva contaminating Tinca tinca. Other examples of Ameiurus species are given below:

Ameiurus natalis (Yellow bullhead). This species is easy to identifty in shipments of tropical fish and fish to be stocked for anglers and it is therefore unlikely to be accidentially introduced into new areas. Internationally this species is not very popular although it is possible that it may be used in aquaculture in the future and intentionally introduced into warmer climates overseas (Godard, 2015a). However, the addition of the Yellow Bullhead (Ameiurus natalis) to British Columbia’s aquatic biota is not to be celebrated, and probably represents one more case of a contaminant species accidentally released with a transplant of game fish. Its introduction likely was accidental with a shipment of Largemouth Bass (Micropterus salmoides) rather than dispersal from Washington (Hanke et al, 2006).

Ameiurus brunneus (Snail Bullhead):For example,

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in some States of the United States of America, A. brunneus is not native but invasiveand its introduction may have resulted from stock contamination of black bullheads (Ameiurus melas) that were stocked in Belews Lake, North Carolina, on the upper Dan River (Pam Fuler, 2017).

1.5. How likely is the organism to survive during passage along the pathway (excluding management practices that would kill the organism)?

Subnote: In your comment consider whether the organism could multiply along the pathway.

likely medium Transport conditions could afford survival although it’s unlikely to breed.

For A. melas, the considerable tolerance to water pollution, turbidity, low oxygen concentration, elevated temperatures and a range of pH values (Novomeská et al., 2013) makes it resistant to bad conditions in transport. Its spread has been undoubtedly facilitated by its ability to survive low oxygen concentrations for prolonged periods (Scott and Crossman, 1973).

A. natalis is able to withstand extremely low oxygen levels (0.1-0.3 ppm), has a wide tolerance of temperatures and is able to “hibernate” which allows it to survive serious winterkill conditions within northern sections of its native range (Cooper and Washburn, 1949). It has also been reported that A. natalis can survive out of water for a number of hours.

1.6. How likely is the organism to survive existing management practices during passage along the pathway?

likely medium A species tolerant of pollutants (Ribeiro et al. 2008 ), low dissolved oxygen (3.0 mg L −1 ; Stuber 1982 ), and elevated water temperatures (up to 35°C; Scott and Crossman 1973 ), the black

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https://link.springer.com/article/10.1007/s11160-016-9436-z#CR105




bullhead also has a specialized, nest-guarding, reproductive strategy (Stuber, 1982 ) could survive in enough numbers to reproduce once in a suitable habitat.

1.7. How likely is the organism to enter Europe undetected?

moderately likely medium Big stocks wouldn’t be subject of extensive control.

1.8. How likely is the organism to arrive during the months of the year most appropriate for establishment?

likely medium As indicated by Scott and Crossman ( 1973 ), b lack bullhead is described as a batch spawning species, with reproduction initiated when waters reach ≈21 C, but tolerates temperature between 8 and 30ºC ( Baensch and Riehl, 1991).Ameiurus natalis prefere temperatures between 5°C and 25°C (Aquaric Republic Network, 2017).Ameiurus nebulosus tolerates the most broad range of temperaturas: 0°C - 37°C (Beitinger and Bennett, 2000.) so it could establish any moment of the year.Ameiurus platycephalus belongs to a temperate climate, which would allow it to establish in most parts of Europe.Ameiurus brunneus, A. serracanthus and A. catus are subtropical (no information about tolerated temperatures in www.fishbase.us).

So, it depends of the species and the temperature in the area of entry, but the climate being similar of their area of origin is more probable to encounter water temperature appropriated to survive and reproduce.

1.9. How likely is the organism to be able to transfer likely medium It will depend on the kind of the aquaculture

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http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatget.asp?spid=4553




from the pathway to a suitable habitat or host? facility, , as well as on the management carried out. (COUNCIL REGULATION (EC) No 708/2007 of 11 June 2007 concerning use of alien and locally absent species in aquaculture points out the closed aquaculture facilities to avoid escapes).In case of escapes, it would be easy to find a suitable habitat.


moderately likely low Due to stricter controls and the use of closed aquaculture facilities we consider it moderatily likely. However we recognize low confidence in the answer.

Pathway name: [Intentional stocking for sport fishing and food]



Intentional medium North American catfish species, such as black bullhead Ameiurus melas (Rafinesque), brown bullhead Ameiurus nebulosus (LeSueur) and channel catfish Ictalurus punctatus (Rafinesque), as well as the European catfish Silurus glanis L., have been introduced into ponds throughout Europe for sport fishing (Gozlan et al, 2010).

This pathway is still possible between countries or for Ameiurus species that are not present in Europe yet. Ameiurus catus has been introduced in some areas of the USA trough intentionally stocked for sport and food (https://www.nature.nps.gov/water/marineinvasives/assets/PDFs/GreatLakes/Ameiurus_catus.pdf

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https://www.nature.nps.gov/water/marineinvasives/assets/PDFs/GreatLakes/Ameiurus_catus.pdf

https://www.nature.nps.gov/water/marineinvasives/assets/PDFs/GreatLakes/Ameiurus_catus.pdf


In conclusion there is a possibility that new species of Ameiurus to be imported for trade. This possibility is unlikely for the species that established in Europe, but if demand for other species of Ameiurus exists, this possibility is not to be discarded.



moderately likely low A large number of a new species of Ameiurus could entry if a high demand for such species would happen in aquaculture or sport fishing.

1.9. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host?

likely medium Having in mind the success of the two representants of this genus and the suitability of habitats in Europe (based on tolerated water temperatures and high plasticity for adverse conditions), probably it would be easy for other Ameiurus species to find a suitable habitat once they entered.


moderately likely low There is no information about the demand of this species in stocking for sport fishing. That could change depending on demand.

End of pathway assessment, repeat as necessary.

1.11. Estimate the overall likelihood of entry into Europe based on all pathways (comment on the key

moderately likely medium Estimating the three pathways considered we support the overall likelihood could be moderately

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issues that lead to this conclusion). likely but with a medium confidence.

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PROBABILITY OF ESTABLISHMENT

Important instructions: For organisms which are already well established in Europe, only complete questions 1.15 and 1.21 then move onto the spread section. If

uncertain, check with the Non-native Species Secretariat.

QUESTION RESPONSE CONFIDENCE COMMENT

For A. melas and A. nebulosus:

1.15. How widespread are habitats or species necessary for the survival, development and multiplication of the organism in Europe?

widespread high AmeriurusFour of the species of the genus Ameiurus - A. melas and A. nebulosus (well established in Europe) and A. natalis and A. catus - have the ability to tolerate, survive or adapt to a wide variety of environmental conditions. There’s no scientific knowledge about the potential ability for the other species.

Marchetti et al (2004), based on Lever (1996), point out 21 countries in which A. melas has been introduced and successfully established. They point out the same number for A. nebulosus. Moore et al (2010) indicate that A. melas, A. natalisand A. nebulosus have a widespread distribution outside the species natural range.

Bearing in mind the precautionary principle, it could be stated that the species of the genus could invade almost all the inland water surfaces. So, water areas and wetland accounted for 4.8 % of the EU surface (Eurostat, 2017).

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Ameiurus melas (Black bullhead) inhabits in irrigation channels, lakes, ponds and reservoirs, which are the principal habitats. Rivers and streams are secondary habitats (CABI, 2015a)

Black bullhead is classed as a warm-water species, and. In its native range, the species is found in the downstream sections of smalltosmall to-medium-sized streams of low gradient, ponds and backwaters of large rivers and silty, soft bottomed areas of lakes and impoundments. Black bullhead are said to be most abundant in smaller water bodies, especially artificial and heavily managed ponds (Copp et al, 2016).

This demersal species inhabits slow-flowing habitats (limnophilic) with soft substrata in all riverine and lacustrine environments, including artificial ones such as ponds and reservoirs (Leunda et al., 2008), with an opportunistic dietary.. Black bullhead are said to be most abundant in smaller water bodies, especially artificial and heavily managed ponds. It is considered a warm-water species (Godard, 2015b; Copp et al, 2016; Leunda et al., 2008).

Previous research on The numerous dams constructed for river regulation and as hydropower plants in Europe are an excellent opportunity for further expansion of its range (Cvijanovic et al., 2008).

Black bullhead suggests that it is highly tolerant to

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environmental degradation andwhich are considered more susceptible to invasion (Moyle,1986) and it is capable of living with poor water quality conditions (Ribeiro et al. 2008).

One of the greatest concerns in the case of the black bullhead, is associated with degraded or impacted ecosystems, which are considered more susceptible to invasion (Moyle, 1986). This facilitates invasions by species such as the black bullhead (Hanchin et al. 2002), which have been found to benefit in growth terms from increasing eutrophication. Increasing eutrophication benefits the growth of this species. Indeed, all of these factors contribute to the black bullhead’s potential as a successful invader (e.g. Gante and Santos, 2002; Koščo et al. Hanchin et al.2002; Koščo et al., 2004; Dextrase and Mandrak, 2006).

That being said, black bullhead has a great potential to invade and establish viable populations in new areas, and this is facilitated by life-history plasticity. However, the risk posed by black bullhead will vary according to local environmental conditions, and this is apparent in the FISK rankings of this warm-water species, which is perceived in the north of Europe (Finland) as posing a lower risk of becoming invasive than in countries of intermediate or lower latitudes. (Puntila, 2013).

Across Europe, numerous dams were constructed for river regulation and as hydropower plants, which lead

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to water flow lag. Since black bullhead inhabits soft substrates of sluggish sections of creeks and rivers, as well as backwaters, channels, swamps and impoundments, this was excellent opportunity for further expansion of its range (Cvijanovic et al., 2008).

Ameiurus nebulosus inhabits brackish waters and estuaries are secondary habitats as irrigation channels. Principal habitats are lake, ponds, reservoirs, rives and streams (CABI, 2015b).

Ameiurus natalis inhabits irrigation channels, lakes, ponds, reservoirs rivers and streams (CABI, 2015c).

Suitable habitats are present and widely distributed in the Risk Assessment Area for Ameiurus spp.

Ameiurus nebulosus (Brown bullhead):This species inhabits lakes, ponds, reservoirs, rivers and streams as principal habitats and brackish waters, estuaries and irrigation channels as secondary habitats. (Mandrak, 2009).Its establishment, once introduced, was likely assisted by its generalist, omnivore diet with feeding aided, even in turbid waters, by its chin barbels (Mandrak, 2009)As included in Coop et al (2016) the decline of brown bullhead in some European countries, e.g. Belgium (Verreycken et al. 2007), Czech Republic (Lusk et al.

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2010) and Poland (Grabowska et al. 2010), has coincided with an increase in the distribution and abundance of black bullhead in Central and Eastern Europe (Nowak et al. 2010b); these contrasting patterns have led to suggestions that black bullhead is displacing brown bullhead. However, the two species have overlapping native distributions (see species fact sheets at: www.usgs.org), so this may simply be coincidental. However, further study is needed to determine whether or not this is artifact or indicative of black bullhead displacing brown bullhead.

1.21. How likely is it that biological properties of the organism would allow it to survive eradication campaigns in Europe?

very likely high Ameiurus melas

As compiledThis information includes references for the species already presented in Nowakthe European Union.

Moore et al (2010),) state that all Ameiurus species, except A. serracanthus, present a moderate population growth, according to the criterion “resilience” which indicates the rate of population doubling as an indicator of the rate of potential population growth. This is likely to be a good indicator of the rate of population expansion (i.e. range extension) once established. This attribute is also likely to provide an indication of the difficulty of eradication once established.

The characteristics of resistance to degraded or impacted environments are common to at least four of the species of Ameiurus (A. melas. A. nebulosus, A.

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natalis and A. catus). Moreover, due to their high fecundity and ecological plasticity, both A. melas and A. nebulosus are difficult to eradicate once established. Then, bearing in mind the precautionary principle, it should be considered very likely that biological properties of all the species of the genus would allow them to survive eradication campaigns in Europe, especially in rivers.

A. melas and A. nebulosus can tolerate poor river conditions, wide temperature tolerance. The lack of native competitors and predators could lead to a further range expansion in Europe.

Ameiurus melas (Black bullhead)is a typical limnophilic and one of the most tolerant fish species capable of resisting water pollution (Ribeiro et al., 2008). Due to their high fecundity and ecological plasticity, both A. melas and A. nebulosus are considered invasive species 2008; Nowak et al., 2010). Marchetti et al (2004) assigne life history attributes for all fish species in California based on a survey of current literature and personal experience and they provide the same results about A. melas tolerance, that is, it’s an extremely tolerant fish capable of living in waters with water quality that excludes most other fishes and this trait could help to survive eradication campaings in Europe.

The black bullhead has several characteristics associated with successful invaders (Ribeiro et al., 2008), such as high reproductive potential, parental

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care, opportunistic feeders, aggressive behaviour andThe considerable tolerance to water pollution, turbidity, low oxygen concentration, elevated temperatures and a range of pH values (Novomeská et al., 2013). 2013) makes A. melas resistant to methods of eradication. Its spread has been undoubtedly facilitated by its ability to survive low oxygen concentrations for prolonged periods (Scott and Crossman, 1973).

Novomeská et al. (2013) demonstrated that the morphological variability itself is not necessarily essential for invasive success. The invasiveness of black bullhead is therefore probably favoured by variations in its life-history traits and reproduction variables, together with some behavioural traits, e.g. generalist/opportunistic feeding, parental care (Scott and Crossman 1973; Ribeiro et al. 2008) rather than by phenotypic plasticity expressed in external morphology.

Marchetti et al (2004) point out other biological traits which can help to A. melas to avoid a eradication campaign;it’s an omnivorous species that has a high fecundity and lifespan.

Ameiurus nebulosus (Brown bullhead)

Once introduced, A. nebulosus is easy to establish thanksMoore et al (2010) classifie this species as “high” about the “hardiness”, criterion used as an indicator of the species’ ability to tolerate, survive, or

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adapt to a wide range of temperatures, pH, salt or freshwater aquatic environments, or the ability to survive out of water for extended periods of time.

Due to its generalist, omnivore diet, high tolerance to water pollution, turbidity, low oxygen concentration, elevated temperatures and a range of pH values and assisted by its chin barbells, it is very easy to adapt to all kind of waters even in turbid waters, assisted by its chin barbelsonce (Scott and Crossman, 1973). Conversely,

A.nebulosus is a moderately strong swimmer (Scott and Crossman, 1973) that is capable of surviving degraded, warmwater freshwater environments.

A.nebulosus has similar biological traits pointed out by Marchetti et al (2004) which can help A. melas to avoid eradication campaigns; it’s an omnivorous species with a high fecundity and lifespan. Moreover, it’s a tolerant species capable of living in waters in which water quality often reaches their limits of physiological tolerance for short periods.

Its stout shape and strong dorsal and pectoral fin spines would minimize predation by native predators., which would make unlikely biological control. Its parental care of eggs and young would also reduce mortality in the young (Scott and Crossman, 1973).

It is nearly impossible to eradicate them when it is established in a river. In small, closed waters (e.g.

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small lakes or ponds), control could be possible.

In a fishery in North London the black bullhead have spread, the risk to the wider environment was significant; so a piscicide based eradication was carried out by the National Fisheries Services Virtual Non-native Species Management Team in May 2014. It seems they managed to remove the only known population of the highly invasive black bullhead from a fishery in Essex, England (https://marinescience.blog.gov.uk/2015/08/07/eradicating-black-bullhead-catfish/).(Brazier, 2015).

As compiled in Nowak et al (2010), Ameiurus melas is a typical limnophilic and one of the most tolerant fish species capable of resisting water pollution (Ribeiro et al., 2008). Due to their high fecundity and ecological plasticity, both A. melas and A. nebulosus are considered invasive species (Gante and Santos, 2002; Koščo et al., 2004; Dextrase and Mendrak, 2006).

The black bullhead has several characteristics associated with successful invaders (Ribeiro et al., 2008), such as high reproductive potential, parental care, opportunistic feeders, aggressive behaviour and considerable tolerance to water pollution, turbidity, low oxygen concentration, elevated temperatures and a range of pH values (Novomeská et al., 2013). Its spread has been undoubtedly facilitated by its ability to survive low oxygen concentrations for prolonged

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periods (Scott and Crossman, 1973).

The characteristics of successful invaders are common to at least four of the species of Ameiurus, so we can affirm that biological properties of the genus would allow it to survive eradication campaigns in Europe.

For A. natalis and A. catus and the possible other 3 species (A. brunneus; A. platycephalus and A. serracanthus):

1.12. How likely is it that the organism will be able to establish in Europe based on the similarity between climatic conditions in Europe and the organism’s current distribution?

very likely medium According to Koppen-Giger climatic classification, temperatures of the States from USA where these species are natives are similar to the temperatures of most of the European countries (mainly from central-south Europe) (See Q.4)

Ameiurus natalis (Yellow bullhead):This eurythermal species rangs from southern Canada to northern Mexico.There are a number of reports of its introduction into Italy (Welcomme, 1988; Holčík, 1991). Gandolfi et al, 1991) also informed about the occurrence of the yellow catfish in Italy.

Ameiurus catus (White catfish) A. catus requires water above 20 °C in summer (NatureServe, 2013). In Sapin, and probably other suthern countries there are water rivers or reservoirs where there are water temperatures up to 20 ºC.Recorded in UK (Britton and Davies, 2006).

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Ameiurus brunneus (Snail Bullhead):Introduced populations are established in Virginia, North Carolina and Georgia (USGS Nonindigenous Aquatic Species Database). Temperatures of these states are similar to mid-south Europe. Koppen-Giger classification within tipe C (warm climates)

Ameiurus platycephalus (Flat bullhead)Distribution similar and a little bit more up north than the former species (NatureServe, 2013). No much difference with southern Europe temperatures.

Ameiurus serracanthus (Spotted bullhead)Spotted bullheads are limited to the Chattahoochee River drainage in Alabama. Although they appear to be rare in state waters, their limited distribution may be due to insufficient sampling of preferred habitats using large nets and boat electrofishing gear.

1.13. How likely is it that the organism will be able to establish in Europe based on the similarity between other abiotic conditions in Europe and the organism’s current distribution?

very likely high Other north American bullheads have already established populations in Europe because they have found in Europe temperature, radiation, humidity and soil quite similar to their native range.

According to Froese et al. (2016) and Aquatic Republic Network (2017):

Ameiurus natalis (Yellow bullhead)A hardy fish that can live in a wide variety of conditions. Able to withstand lower temperatures. Can be maintained in outdoor ponds if winters are

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mild. Inhabiting waters within a pH range 6 and 8. and temperatures range within 5 and 25 ºC.

A. natalis can tolerate acidic waters with low oxygen and high carbon dioxide levels. In addition to this it is eurythermal, ranging from southern Canada to northern Mexico (Godard, 2015a).

Ameiurus catus (White catfish)Very tolerant of brackish water. These fish are often found near deltas where a river meets the sea. Inhabiting waters within a pH range 6,6 and 8,6, and a temperature range within 10 and 23 ºC.

Ameiurus brunneus (Snail Bullhead)Needs highly oxygenated water. Inhabiting waters within a pH range 6,6 and 7,8. Temperature range within 18 and 26 ºC.

Ameiurus platycephalus (Flat bullhead)Generally tolerant of water with low dissolved oxygen levels. Inhabiting waters within a pH range 6,6 and 7,8. and a temperature range within 18 and 26 ºC.

Ameiurus serracanthus (Spotted bullhead)The species is very tolerant generally even towards brackish water, inhabiting waters within a pH range 6,6 and 8,4 and a temperature range within 15 and 24 ºC.

1.14. How likely is it that the organism will become established in protected conditions (in which the

very likely very high In these protected conditions it is much easier to control external conditions as temperature, light or

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environment is artificially maintained, such as wildlife parks, glasshouses, aquaculture facilities, terraria, zoological gardens) in Europe?

Subnote: gardens are not considered protected conditions

humidity which will make it also easier for the animals to survive.Riverine: deep holes of small to medium rivers with slow to swift currents and rock substrates or sand bottoms; it also occurs over mud bottoms, typically near stumps, in impoundments. (Naturserve, 2013b).

1.15. How widespread are habitats or species necessary for the survival, development and multiplication of the organism in Europe?

widespread high Wareas and wetland accounted for 4.8 % of the EU surface (Eurostat, 2017). . Taking into account the generalist behaviour of the most of the species of the genus (Ameiurus spp) they could invade almost all the water surfaces, primarily downstream sections of small to-medium-sized streams of low gradient, ponds and backwaters of large rivers and silty, soft bottomed areas of lakes and impoundments.

Ameiurus natalis (Yellow bullhead)This species inhabits irrigation channels, lakes, ponds, reservoirs rivers and streams (Godard, 2015a).

Ameiurus catus (White catfish)This species inhabits sluggish, mud-bottomed pools, open channels, and backwaters of small to large rivers; also in lakes and impoundments (Murdy et. al, 1997). –In conclusion, suitable habitats are present and widely distributed in the Risk Assessment Area for Ameiurus spp.

Ameiurus brunneus (Snail Bullhead)The Snail Bullhead is found in rocky riffles, shoals, runs, and pools in streams and rivers. (Jenkins and Burkhead 1994; Rohde et al. 1994; NatureServe

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2013).

Ameiurus platycephalus (Flat bullhead)The Flat Bullhead is typically found in streams, rivers, and impoundments occupying areas with mud, sand, or rock bottoms, with slow-flowing water along the banks and in pool areas (Jenkins and Burkhead, 1994; Rohde et al. 1994; NatureServe, 2013).

Ameiurus serracanthus (Spotted bullhead)The spotted bullhead is known from mainstem and large tributaries. It prefers rocky substrates with moderate currents, and has been collected occasionally over mud near vegetation or other structures such as old stumps in impounded portions of rivers (Georgia Department of Natural Resources, 2013).

1.16. If the organism requires another species for critical stages in its life cycle then how likely is the organism to become associated with such species in Europe?

NA very high The lack of native competitors and predators could lead to a further range expansion in Europe for these opportunistic species.

Ameiurus natalis (Yellow bullhead)Like all other catfish species, yellow bullheads are opportunistic feeders. Yellow bullheads feed at night on a variety of plant and animal material, both live and dead, most commonly minnows, crayfish, insects and insect larvae, snails, clams, other small aquatic organisms, decaying animal matter, and worms. Compared to the other bullheads, the yellow bullheads consume more aquatic vegetation. The young will feed on aquatic invertebrates.

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It locates prey by brushing the stream bottom with its barbels. Taste buds on the barbels tell the bullhead whether or not contact is made with edible prey. consisting of insects,(Jenkings, 2006).

Ameiurus catus (White catfish)Feeds on wide variety of fishes, insects and crustaceans (Froese et al., 2016).

Ameiurus brunneus (Snail Bullhead)Small fishes, aquatic vegetation, and snails of the genus Elimia make up the snail bullhead’s diet (Mettee et al., 1996).

Ameiurus platycephalus (Flat bullhead) feeds on aquatic insects, small fishes, and snails (Froese et al., 2016).

Ameiurus serracanthus (Spotted bullhead)No detailed studies of diet and life history have been made. Residents of northern Florida often refer to the spotted bullhead as "snailcat," due to the large quantities of mollusks it consumes. The original description reported four different species of mollusks identified from stomach contents (Georgia Department of Natural Resources, 2013).

1.17. How likely is it that establishment will occur despite competition from existing species in Europe?

likely medium A. natalis and A. catus have been already recorded in the European Union, although there is no information available about the establishment of A. catus in UK or about A. natalis in Italy (where they certainly have been introduced) or in other countries in Europe.

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The other 3 species (A. brunneus; A. platycephalus and A. serracanthus) could have a similar behaviour related to competence.

In the case of Iberian peninsula, most of the exotic fish species were characterized by large size, long longevity, late maturity, high fecundity, few spawnings per year, and short reproductive span, whereas Iberian native species exhibited predominantly the opposite suite of traits. Native and Iberian exotic species more adapted to strong seasonal patterns of flow could survive due to its lower sizes and to multiple spawnings that prevent the loss of all offspring after flood disturbances (Vila-Gispert et al. 2005). That means that for some species and areas, native species will be weaker in relation to competition.

1.18. How likely is it that establishment will occur despite predators, parasites or pathogens already present in Europe?

likely medium It is difficult to foresee this issue but taking into account that predators, parasites or pathogens didn´t prevent the establishment of the existing Ameiurus species in Europe, it won’t prevent probably the possible establishment of other Ameiurus species. Marchetti et al (2004) refers to A. natalis and A. catus as having a high maximum adult size (standard length) and this trait could help to avoid predation.

1.19. How likely is the organism to establish despite existing management practices in Europe?

likely high The establishment of Ameiurus species (A. natalis, A. catus, A. brunneus, A. platycephalus and A. serracanthus) may display a similar success as per previous introductions of other fishes throughout Europe (e.g. Silurus glanis, Esox lucius, Sander

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lucioperca, Perca fluviatilis).

The removal of unwanted organisms from aquatic environments (water) is much harder to address compared to the terrestrial environment (land). In a large water system, it could be especially difficult to eradicate the newcomer.

Once they are introduced to a water body, it is very difficult to control their spread or completely eradicate them. Therefore, preventing the introduction and spread of these species is the best line of defence.

1.20. How likely are management practices in Europe to facilitate establishment?

unlikely low Wrong management practices can permit escapes from ponds or movements from one water basin to another. No regulated activities as the ornamental commerce and illegal activities, like fish transfers by anglers between water bodies may facility the invasion of these new species.

Moore et al (2010) note that if trade in a species has been restricted elsewhere, it may suggest that the species has been recognised by that country as a potential threat, for one reason or another, and so may pose a similar threat if introduced to Australia (and it could be applicable to Europe). However, trade may be restricted for a variety of reasons not related to pest invasiveness. This information is difficult to ascertain and is likely to be available only for a limited number of countries. The restricted trade in the Ameiurus species is unknown.

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1.21. How likely is it that biological properties of the organism would allow it to survive eradication campaigns in Europe?

very likely high The biological traits outlined in the following points (1.22 to 1.25) would allow Ameiurus species to survive eradication campaings, so we consider them to answer this question.

The tolerance of most of the species of the genus and their characteristics of resistance to degraded or impacted environments are common to at least four of the species of Ameiurus (A. natalis, A. catus, A. platycephalus and A. serracanhus)), so we can affirm that it is possible that biological properties of all Ameiurus spp would allow them to survive eradication campaigns in Europe, especially in rivers.

1.22. How likely are the biological characteristics of the organism to facilitate its establishment?.

moderately likely

medium Marchetti et al (2004) points out biological traits which can help A. natalis and A. catus to establish. Both species have a notable maximum fecundity and guard their embryos and/or larvae (parental care). They have a high maximum adult size and an important maximum lifespan. A. catus is mainly carnivore and A. natalis invertivore and related to their size of native range, they occupy >50% of one zoogeographic sub-region.

Ameiurus natalis (Yellow bullhead) is able to withstand extremely low oxygen levels (0.1-0.3 ppm), has a wide tolerance of temperatures and is able to “hibernate” which allows it to survive serious winterkill conditions within northern sections of its native range. It has also been reported that A. natalis can survive out of water for a number of hours (Godard, 2015a). Intentional stocking has been

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reported as this species can be introduced into degraded watercourse due to their high tolerance to pollution (Klossner, 2005. In Godard, 2015a).

Ameiurus catus (White catfish)High tolerance for salinity (Fuller and Neilson, 2017.)

Ameiurus brunneus (Snail Bullhead)The life history of this species is not well known. Yerger and Relyea (1968) indicate that it has a protracted spawning season that may last from late winter to mid-summer (Barton 2005).

Ameiurus platycephalus (Flat bullhead)In their natural habitats (rivers and streams), Flat Bullheads typically reach maximum adult sizes of 294 mm (Rohde et al. 1994). However, in disturbed habitat such as impounded river reaches and reservoirs, they reach substantially greater sizes (443 mm, 17.6 in.) (Department of Natural Resources, South Carolina, 2013).

Ameiurus serracanthus (Spotted bullhead)Little is known concerning the life history of the spotted bullhead. Gonad development data suggest that spawning may begin in late winter and extend through spring and early summer. Small individuals less than 30 mm (1.2 in) long have been collected from late June through November, suggesting a protracted spawning season (Georgia Department of Natural Resources, 2013).

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1.23. How likely is the capacity to spread of the organism to facilitate its establishment?

moderately likely

high Moore et al (2010) state that all Ameiurus species, excepting A. serracanthus, present a moderate population growth, according to the criterion “resilience” which indicates the rate of population doubling as an indicator of the rate of potential population growth. This is likely to be a good indicator of the rate of population expansion (i.e. range extension) once established. This attribute is also likely to provide an indication of the difficulty of eradication once established.

A.natalis and A.catus live in other countries then their native range.

Ameiurus natalis (Yellow bullhead)Its preferred native habitats are warm. The scarcity of permanent streams with clear, well-vegetated inshore areas, may limit its spread. (McGinnis, 2006).

Ameiurus catus (White catfish). The white catfish, native to the Atlantic coastal states, was introduced into California in 1874 from the Raritan River, New Jersey, by Livingston Stone at the request of the California Fish Commission. Either 56 or 74 were planted in the San Joaquin River near The spread of white catfish was rapid, and today it is common in the Central Valley, particularly in the Sacramento-San Joaquin Delta, in Clear Lake, and in many scattered waters throughout California. It has also been stocked by the State in many waters. (Dill et al, 1997).

Ameiurus brunneus (Snail Bullhead)

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There is not much information on this issue. Observations in Florida indicate that it has a protracted spawning season that may last from spring through mid-summer (Yerger and Relyea, 1968).Data on dispersal and other movements generally are not available. Separation distance (in aquatic kilometers) is arbitrary but reflects the likely low probability that two occupied locations separated by less than several kilometers of aquatic habitat would represent truly independent populations over the long term (NatureServe, 2017).

Ameiurus platycephalus (Flat bullhead)There is not much information on this issue.

Ameiurus serracanthus (Spotted bullhead)Spotted bullheads have the smallest range of any bullhead catfish in the U. S. as well as the world. Although they appear to be rare in state waters, their limited distribution may be due to insufficient sampling of preferred habitats using large nets and boat electrofishing gear (Mettee et al., 1996)

1.24. How likely is the adaptability of the organism to facilitate its establishment?

likely high Although adabtability and tolerance are not synonymous concepts, tolerance of Ameiurus species could give a clue about the adaptability of the species.

Midway et al (2014) modelled occurrence probabilities of 126 stream fish species (5 Ameiurus spp included) sampled throughout North Carolina, many of which occur more broadly in the southeastern USA. Specifically, they developed

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species-specific occurrence probabilities from hierarchical Bayesian multispecies models that were based on common land use (forest, development and agriculture) and land cover covariates to estimate their tolerance category.

Moore et al (2010) state that all Ameiurus species, excepting A. serracanthus, present a moderate population growth, according to the criterion “resilience” which indicates the rate of population doubling as an indicator of the rate of potential population growth. This is likely to be a good indicator of the rate of population expansion (i.e. range extension) once established. This attribute is also likely to provide an indication of the difficulty of eradication once established.

Marchetti et al (2004) assigne life history attributes for all fish species in California based on a survey of current literature and personal experience and they point out thatA. catus is an extremely tolerant species capable of living in waters with water quality that excludes most other fishes. Related to A. natalis it’s a tolerant species capable of living in waters in which water quality often reaches their limits of physiological tolerance for short periods

A.nebulosus ans A. platycephalus were classified as a tolerant species for forest degradation and development and agricultural landscape use. A. natalis was classified as tolerant for forest

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degradation and agricultural land scape use. A. catus was classified as tolerant for forest degradation and development and A. brunneus was classified as intermediate tolerant for development, taking in mind that occurrence patterns for intermediate species in the study were more similar to those of intolerant species than to those of tolerant species.

Midway et al (2014) hypothesize that land use impacts tolerant species differently than intermediate and intolerant species. For example, tolerant species could comprise a greater proportion of introduced species, which include more generalists than other groups.

Other studies have shown that introduced species can be linked to landscape-level characteristics (Lapointe and Light, 2012) and that invasive species may be more suited to anthropogenically disturbed habitat (but for insects: Grez et al. 2013). Either explanation or both explanations could support the unique occurrence probability patterns they found. They also found that it took a relatively small amount of land use change for tolerant species to become the dominant species group (i.e., most likely to occur). Tolerant species were projected to be the most common species by the time 20% of catchment cover was either agricultural land or developed land. Particularly concerning was the fact that tolerant species became more common than intolerant species when anthropogenic land use in the catchment was as little as 5% (Midway et al., 2014).

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Apart from the given information in the point 1.22 of this chapter, since adaptability is bound to biology, the following information about each species is presented:

Ameiurus natalis (Yellow bullhead)Moore et al (2010) classify this species as “high” about the “hardiness”, criterion used as an indicator of the species’ ability to tolerate, survive, or adapt to a wide range of temperatures, pH, salt or freshwater aquatic environments, or the ability to survive out of water for extended periods of time.

There are information coming from non-scientific sources but that may be interesting:”They (A. natalis) inhabit virtually every farm pond which has not been specifically stocked with channel catfish. They are considered to be worthless by most people, since they are about 1/3 head and dress out to nothing. I've seen them thrive in the worst possible environments, even in ditches that went nearly dry during August. In overcrowded ponds they mature at only a few inches in length. I once placed three of these stunted fish in a deep but leaky pond. I did this in March. In August when the pond was reduced to a six inch deep puddle the three fish were approximately one pound and there were hundreds of little ones (Scotcat, 2016).

On the other hand Kilby (1955) observed in the field a salinity tolerance typical from freshwater fish species (15 ‰).

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https://www.scotcat.com/factsheets/a_natalis.html


Ameiurus catus (White catfish)Kendall et al (1968) found upper lethal temperatures up to 31.2 ºC similar to A. melas and A. nebulosus (35ºC) and as salinity tolerance 14,8 ‰, similar to A. melas (13,8‰,) and A. nebulosus (15 ‰).

Ameiurus brunneus (Snail Bullhead)Usually found in slow-flowing or standing waters (Barton 2005).

Ameiurus serracanthus (Spotted bullhead)Riverine: deep holes of small to medium rivers with slow to swift currents and rock substrates or sand bottoms; it also occurs over mud bottoms, typically near stumps, in impoundments. (Naturserve, 2013b).

1.25. How likely is it that the organism could establish despite low genetic diversity in the founder population?

moderately likely

low Certainty is low as there is no information on these Ameiurus species but taking into account that some other fish species have the ability to establish despite low genetic diversity (See Channa spp. risk assessment) we consider it as moderately likely.

1.26. Based on the history of invasion by this organism elsewhere in the world, how likely is to establish in Europe? (If possible, specify the instances in the comments box.)

likely high Moore et al (2010) indicate that A. natalis has a widespread distribution outside the species natural range and A.catus has a limited distribution outside the species natural range, typically in the same continental region, and that A. platycephalus and A. serracanthus, at the moment of their publication, haven’t established populations outside the species natural range.

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According the history of known invasions, most of them inside the USA territory, it it is likely that most of Ameiurus species could establish populations in Europe.

Ameiurus natalis (Yellow bullhead)This species is native to Atlantic and Gulf Slope drainages from New York to Mexico, the St. Lawrence River, the Great Lakes, and the Mississippi River Basin from North Dakota to the Gulf of Mexico and they have been introduced to at least 14 states outside of their native range (Hanke, 2006).

Ameiurus catus (White catfish) was introduced into the Choctawhatchee, Tennessee, Cahaba, Coosa and Tallapoosa drainages, and the Mobile Delta, Alabama ; the lower White, lower Ouachita, lower St. Francis, lower Red (Lake Erling), and Arkansas drainages, and the Illinois system, Arkansas; at least 22 counties in California including sites in the Sacramento, San Joaquin, Suisun Bay, central California coastal, Tulare-Buena Vista lakes, and San Francisco Bay drainages;most basins in Connecticut ,the panhandle west of the Apalachicola basin, Florida; the Illinois, Mississippi, and Kaskaskia rivers in Illinois; northern and southern Indiana, ; reported in the Mississippi River pool 16, Iowa ; the Ohio River, Kinniconick and Tygarts creeks, and Greenbo Lake in Kentucky; the lower Kennebec River and Merrymeeting Bay in Maine ;the Charles, Connecticut, and Merrimack drainages in Massachusetts ;the Tombigbee River system, Mississippi;Missouri River drainage in

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Missouri;the Truckee, Carson, and Humboldt rivers in Nevada; the French Broad River; the Pigeon and Hiawassee systems in the Tennessee drainage;and in Obids Creek (Upper New drainage) North Carolina; Lake Erie, Sandusky Bay, the mouth of the Portage River, Sippo Lake east of Canton, Springdale Lake near Cincinnati, the Blanchard system, the Muskingum drainage, and the Ohio River in Ohio;the Willamette River and other locations in western Oregon including the Tualatin River;Lake Erie and the Ohio River basin in Pennsylvania; Rhode Island; the Clinch River in Tennessee; and the Cowlitz River and Silver Lake in Washington. This species is introduced into the Lake Erie drainage (state unlisted). White Catfish is also established in several reserviors in Puerto Rico, possibly through stock contamination with channel catfish (Fuller and Neilson, 2016).

Ameiurus brunneus (Snail Bullhead)The Snail Bullhead was collected in 1990 from the Etowah River in Cherokee County, Georgia, and from Amicalola Creek (Etowah system) in Dawson County, Georgia, in 1997.This species was introduced into the upper Roanoke drainage in the Dan River above Kerr Reservoir, Virginia. The first record from the Dan River was in 1976. In 1981, specimens were taken from the Smith River (a Dan River tributary) in Rockingham County, North Carolina It is listed as native and introduced in the Roanoke drainage and it’sas probably introduced in the Roanoke drainage. More recently, specimens have been collected from

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the Little Tennessee River in Franklin County, North Carolina, and from Chatauga Reservoir (Hiwassee drainage), in Clay County, North Carolina.(Fuller, 2017a).

Ameiurus platycephalus (Flat bullhead)This species has been collected from the Chattahoochee River drainage, Georgia. It has been introduced into the French Broad, Nolichucky, Little Tennessee, Toe, and Hiwassee systems of the Tennessee drainage, North Carolina.Two individuals collected from the upper James River in Botetourt County, Virginia, in 1984 may have escaped from a stocked pond.

1.27. If the organism does not establish, then how likely is it that transient populations will continue to occur?

Subnote: Red-eared Terrapin, a species which cannot re-produce in GB but is established because of continual release, is an example of a transient species.

unlikely low This will depend on the number of imported fishes. These data are no easy to obtain.

1.28. Estimate the overall likelihood of establishment (mention any key issues in the comment box).

moderately likely

high Appropriate habitats and climates are found in the EU and the species seems to be tolerant to differents conditions and also very opportunistic, among other biological traits that could help to a successful establishment.

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PROBABILITY OF SPREAD

Important notes: Spread is defined as the expansion of the geographical distribution of a pest within an area.

QUESTION RESPONSE CONFIDENCE COMMENT

2.1. How important is the expected spread of this organism in Europe by natural means? (Please list and comment on the mechanisms for natural spread.)

major high Once established in a basin it is to expect a natural expansion in it. It has several characteristics common to successful invaders, which increases their invasive potential. A. melas and A. nebulosus can tolerate poor river conditions, wide temperature tolerance and a lack of native competitors and predators can facilitate their range expansion along Europe.

Ameiurus melas

In European waters, the dispersal mechanism is not clear but spread of A. melas could be as a result of accidental and illegal introductions or natural dispersion between countries via watercourses (CABI, 2015a)

The black bullhead occurred (imported for aquaculture) in Europe, at first, in France (1871) (Coucherousset et al., 2006). The species expanded relative slowly, however nowadays this is the most widespread North American ictalurid catfish in Europe (Pedicillo, 2008). The expansion was human helped in some cases, while in other situations, a slow, self – managed spreading was observed: for

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example in Spain (first recorded in 1984 (Elvira 1984) and Portugal (first recorded in 2002 (Gante and Santos 2002).

Black bullhead (Ameiurus melas) was introduced to a western Hungarian fish culture in the beginning of the 1980s, and escaped specimens spread rapidly along the Danube. Abundant stocks have developed in most of the backwaters along the Danube (Bódis et al., 2012).The species will undoubtedly increase its introduced range through natural dispersal within drainage networks. The magnitude of spread will be dependent upon the spatial configuration of potential habitats and their connectivity via drainage networks. Most natural dispersal within the native range of Canada and the USA has occurred at local levels (Fuller et al., 1999).

Ameirus nebulosus

In European waters, the dispersal mechanism is not clear but spread could be as a result of accidental and illegal introductions or natural dispersion between countries via watercourses (Nowak et al., 2010; Copp et al., unpublished). Following what is included in Coop et al (2005a) the introduction and dispersal patterns of introduced North American species have varied between European countries. Once introduced, the dispersal rate of A. melas and A. nebulosus in Continental, Atlantic and Boreal zones was medium (Secretariat of NOBANIS, 2012).

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Once established in a basin, natural expansion through escapes and/or dispersal is to be expected following the same known and/or supposed mechanisms that the existing species have followed and which are explained in this section.

For the species introduced in Europe, Recently, in Greece, a self-sustained population of A. nebulosus was discovered and is supposed that the fish was introduced from Bulgaria through the transboundary waters of the Strymon River (Barbieri, 2015).

it is to be noted that oncein the species reachedcase of reaching the Danube River, the Rhine-Main-Danube Canal offers no physical barrier to the spreading of this invasive species from Est to Western Europe (Müller et al., 2002).

The black bullhead occurred (imported for aquaculture) in Europe, at first, in France (1871) (Coucherousset et al., 2006). Some countries, reglementary prohibited A. melas (France, Arrêté du 17/12/1985) and A. neboulosus (Poland, Grabowska et al, 2009), so we consider that human-assisted spread should become less important.

In conclusion the spread by natural means could be more important that by human assistance, in the case of already established species.

We include here reference to the four Ameiurus spp established in the EU.

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Ameiurus melas (Black bullhead):Black bullhead, sometimes misidentified as brown bullhead, was introduced in some countries (e.g. France, Romania, Spain, Italy) in the late 19th/early 20th century, but only began to appear in other European countries in the 1980s (Pintér, 1998: Elvira and Almodóvar, 2001).

In European waters, the black bullhead’s dispersal mechanism is not clear but is likely to be associated with accidental and illegal introductions, followed by natural spread between neighbouring countries via natural and manmade water courses (Nowak et al. 2010b).

The species expanded relative slowly, however nowadays this is the most widespread North American ictalurid catfish in Europe (Pedicillo, 2008). The expansion was human helped in some cases, while in other situations, a slow, self – managed spreading was observed: for example in Spain (first recorded in 1984 (Elvira 1984) and Portugal (first recorded in 2002 (Gante and Santos 2002Pedecillo, 2008).

The expansion was human helped in some cases, while in other situations, a slow, natural spread was observed: for example in Spain (first recorded in 1984 (Elvira 1984) and Portugal, first recorded in 2002 (Gante and Santos, 2002).

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In Spain (Dana et al., 2016) cited the arrival of A.melas at Majalberraque stream probably due to the natural dispersion that takes advantage of the connection of the rice paddy system and its network of canals with the Guadalquivir. The locality of the Brazo del Este cited by García-de Lomas et al. (2009) is more than 20 kilometers downstream, which confirms its dispersion on the Guadalquivir River. It is also very likely that the species is much more widespread in the province of Seville.

Black bullhead is widely dispersed in some countries, e.g. Italy (Bianco, 1998), France (Keith et al, 2011) and Portugal (Almaça, 1995), but localized in others: e.g. Spain (Lake Banyoles only: Doadrio et al., 1991), Germany (both black and brown bullhead; Arnold, 1990), and England (Lever, 1977).

Black bullhead (Ameiurus melas) was introduced to a western Hungarian fish culture in the beginning of the 1980s, and escaped specimens spread rapidly along the Danube. Abundant stocks have developed in most of the backwaters along the Danube (Bódis et al., 2012). This escapement was followed, nine years hence, by a population explosion in the wild whereby the species spread rapidly downstream to Lake Balaton (Hungary) (Pintér, 1998) and into Slovenian tributaries of the Danube as well as upstream into side-arms of the Slovak Danube and its tributaries (Kosco et al., 2000).

Brown bullhead populations in the lower Danube

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(Romania) are also thought to have been derived from downstream dispersal of escapee fish from Hungarian fish farms (Copp et al., 2005).

The black bullhead’s range in Slovakia continues to expand, and the same pattern is being observed in the Guadiana and the Tagus basins of Portugal, where black bullhead has rapidly established substantial populations, primarily in reservoirs (e.g. the newly filled Alqueva), and most recently in connected river systems (Copp et al., 2005).

In the case of the Czech Republic, the most probable explanation for its finding in the Lužnice River flood plain might be natural spread of individuals from pond aquaculture, via e.g. pond connecting canals.The species will undoubtedly increase its introduced range through natural dispersal within drainage networks. The magnitude of spread will be dependent upon the spatial configuration of potential habitats and their connectivity via drainage networks. Most natural dispersal within the native range of Canada and the USA has occurred at local levels (Fuller et al., 1999).

Ameiurus nebulosus (Brown bullhead) is a moderately strong swimmer (Scott and Crossman, 1973) that is capable of surviving degraded, warmwater freshwater environments.

European introductions of A. nebulosus occurred

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concurrently, with individuals from North America introduced to Germany for angling, sport and aquaculture in 1885 (Scott and Crossman, 1973), leading to subsequent intentional and unintentional secondary spread to the rest of Europe. A. nebulosus is a moderately strong swimmer (Scott and Crossman, 1973) that is capable of surviving degraded, warmwater freshwater environments; therefore, the species will undoubtedly increase its introduced range through natural dispersal within drainage networks. The magnitude of spread will be dependent upon the spatial configuration of potential habitats and their connectivity via drainage networks. Most natural dispersal within the native range of Canada and the USA has occurred at local levels (Fuller et al., 1999).

In European waters, the dispersal mechanism is not clear but spread could be as a result of accidental and illegal introductions or natural dispersion between countries via watercourses (Nowak et al., 2010).

In Czech Republic, A.nebulosus occurs only locally, without showing any tendency towards spreading (Lusk et al, 2010).

Ameiurus nebulosus is a moderately strong swimmer that is capable of surviving degraded, warmwater freshwater environments; therefore, the species will undoubtedly increase its introduced range through natural dispersal within drainage networks. The magnitude of spread will be dependent upon the

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spatial configuration of potential habitats and their connectivity via drainage networks. Most natural dispersal within the native range of Canada and the USA has occurred at local levels.

A. natalis are(Yellow bullhead) is a sedentary fish which may disperse naturally over short distances (CABI, 2009Godard, 2015a).

A. natalis was intentionally introduced in new waterways by several pathways, including releases from aquariums and intentional stocking in open waters for food and game fish (Godard, 2015a). Also, A. natalis was accidentally introduced via escapes from garden ponds and aquaculture facilities during floods and intentionally introduced in new waterways by several pathways, including releases from aquariums and intentional stocking in open waters for food and game fish (Godard, 2015a).

Ameiurus catus (White catfish) was first introduced as intentional stocking for sport and food. Fuller and Neilson (2017) point out that because of this species' high tolerance for salinity, the original movement to large rivers in Connecticut could have been a natural range extension.

2.2. How important is the expected spread of this organism in Europe by human assistance? (Please list and comment on the mechanisms for human-assisted spread.)

moderatemajor

mediumhigh

The species in this genus was likely spread primarily for recreational angling opportunities.Ameiurus melas (Black bullhead)In the previous section, it was outlined that in European waters, the black bullhead’s dispersal

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mechanism is not clear but is likely to be associated with accidental and illegal introductions, followed by natural spread between neighbouring countries via natural and manmade water courses (Nowak et al. 2010b).

The numerous dams constructed for river regulation and as hydropower plants in Europe are an excellent opportunity for further expansion of its range (Cvijanovic et al., 2008).

The intentional stocking of A. melas for recreational fishing purposes has reduceddecreased in recent years. In Czech Republic, quite recently, evidence was obtained on unintentional introduction of Ameiurus melas with carp stock from Croatia to the fishponds in the Třeboň district in 2003 (Koščo et al. 2004; Lusk et al, 2010). The expansion was human helped in some cases, for example it was imported to Hungary from Italy in 1980 (Harka 1997).

A.nebulosus was first introduced in the Pacific islands (1877) with the release of 100-200 individuals for angling in Auckland, New Zealand. These introductions resulted in local viable populations by 1885 (Holcík, 1991). Additional introductions for angling and sport occurred in Hawaii in 1893 (Welcomme, 1988). melas was historically introduced in 1871 in France when some individuals were imported and during the 20th spread over all the country by the angling societies (Keith et al 2011).

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The intentional stocking of A. melas for recreational fishing purposes has reduced in recent years. In Czech Republic, quite recently, evidence was obtained on unintentional introduction of Ameiurus melas with carp stock from Croatia to the fishponds in the Třeboň district in 2003 (Koščo et al. 2004; Lusk et al, 2010). The expansion was human helped in some cases, for example it was imported to Hungary from Italy in 1980 (Harka 1997).

Although angling for A. nebulosus within Canada is relatively unpopular (Scott and Crossman, 1973), the initial introduction to Europe and the Pacific islands for angling suggests almost global popularity as a sportfish; therefore, unauthorized introductions for angling purposes may occur.

The Brown bullhead (Ameiurus nebulosus) was introduced to Hungary in 1902 and rapidly spread in natural waters because of stockings for recreational reasons (Bódis et al., 2012).

There have been intentional and unintentional, human‐mediate species introductions. Fishes are dispersed beyond their native ranges because they are interesting sporting species, for example, Ameiurus used in aquaculture (Bianco and Ketmaier 2016).

Ameiurus nebulosus (Brown bullhead)In the previous section, it was mentioned than in European waters, the dispersal mechanism of A. nebulosus is not clear but spread could be as a result

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of accidental and illegal introductions or natural dispersion between countries via watercourses (Nowak et al., 2010).A. nebulosus was likely introduced for recreational angling opportunities. Introduction via fisheries (angling/sport purposes) and aquaculture are the dominant long-distance (national; international) vectors. Intentional introductions by fisheries managers may result in long-distance travel events via stocking from source populations. Aquaculture introductions may have similar magnitudes of spread. For example, China (Beijing and Hubei province) stocked A. nebulosus for aquaculture purposes from USA broodstock. Unauthorized introductions by anglers also has the potential to contribute to local, national or international events but may be constrained by the effectiveness of certain legal restrictions that prohibit import of live organisms across borders (CABI, 2015bMandrak, 2009).

TheEuropean introductions of A. nebulosus occurred concurrently, with individuals from North America introduced to Germany for angling, sport and aquaculture in 1885 (Scott and Crossman, 1973), leading to subsequent intentional and unintentional secondary spread to the rest of Europe.

In Poland its natural expansion of the Brown bullhead (Ameiurus nebulosus) was assisted by intentional introductions carried out by angling associations, fish pond´s owners, accidental admixture to the stocking material of the other species and using it as a live bait

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(Hanel et al., 2011Witkowski 2002).

Ameiurus nebulosus have been dispersed beyond their native ranges because they are interesting in aquaculture (sporting species, for example, used in aquaculture (Jonsson and Jonsson, 2016).

The brown bullhead was introduced to Hungary in 1902 and rapidly spread in natural waters because of stockings for recreational reasons (Bódis et al., 2012).

Recently, in Greece, a self-sustained population of A.nebulosus was discovered and is supposed that the fish was introduced from Bulgaria through the transboundary waters of the Strymon River (Barbieri et al., 2015).

Ameiurus natalis (Yellow bullhead)Intentional stocking has also been reported in case of A. natalis as this species can be introduced into degraded watercourse due to their high tolerance to pollution (Klossner, 2005).

Ameiurus natalis is easy to identifty in shipments of tropical fish and fish to be stocked for anglers and is therefore unlikely to be accidentially introduced into new areas.

A. natalis have beenA. natalis was intentionally introduced in new waterways by several pathways, including releases from aquariums and intentional stocking in open waters for food and game fish. Also,

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A. natalis was accidentally introduced via escapes from garden ponds and aquaculture facilities during floods and intentionally introduced in new waterways by several pathways, including releases from aquariums and intentional stocking in open waters for food and game fish (CABI, 2009Godard, 2015a).

Ameiurus catus

Ameiurus catus (White catfish) was recorded as introduced to Europe for the first time in Great Britain. An albino variety of 620 mm fork length and 4550 g was believed to have been an ornamental fish that was introduced subsequently into the wild (Britton and Davies, 2016).

Accidental movement of either their eggs or larvaealevins via anglers’ nets is believed to be the mechanism by which Ameiurus catus may be released (Zięba et al., 2010).

Some countries have forbidden new entries of A. melas and A. neboulosus (France, Poland etc), so we consider that human-assisted spread will become less important.

In conclusion the spread by natural means could be more important that by human assistance.

2.3. Within Europe, how difficult would it be to contain the organism?

very difficult high OnceIt is nearly impossible to eradicate them when these species are established in a river basin, the

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bullheads´. In small, closed waters (e.g. small lakes or ponds), control could be possible.

Public awareness is important to prevent establishment of new populations and to prevent further illegal introductions of these species. Public awareness is essential to prevent misidentification of these species (Godard 2015a, 2015b; Mandrak, 2009).

Eradication may involve the use of chemical agents (e.g., rotenone) to induce mortality within introduced populations, although such methods should be evaluated for their potential effects on non-target fishes. Other measures (e.g., physical removal using fish sampling gears: fyke nets, seines, boat and backpack electrofishers) may also be effective.Physical control should involve, if possible, physical isolation of introduced populations, which may require physical (e.g., block nets) or electrical barriers (Godard 2015a, 2015b; Mandrak, 2009).

Biological control of adult is unlikely given the paucity of natural predators.

The Department of Agriculture and Fisheries of the Queensland Government (2011) in a document which involves the spread of Tilapia but that it’s applicable to Ameiurus or other species, considers that fishes containment is really difficult. Options are available that restrict the ability of a pest fish to naturally disperse throughout a catchment. Dam water levels are often lowered as an ongoing maintenance measure

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to help minimise the risk of flooding. This action, however, only controls the natural spread of pest fish if the process does not involve draining water into another waterway or waterbody. It is also effective only if the pest fish species has not already spread downstream of the dam wall. The construction of screen barriers between infested and uninfested areas is another action that is often used to contain pest fish populations. This is usually undertaken on irrigation channels and pipelines where native fish dispersal is also not desirable. Screen barriers are, however, very costly to establish and require careful planning and ongoing maintenance and monitoring to ensure fish are being contained. Unfortunately, the majority of new pest fish incursions are believed to be the result of human-mediated dispersal rather than natural migration. This fact makes the containment of pest fish populations extremely difficult. Themost effective containment method is therefore considered to be increasing community awareness by distributing a range of pest fish educational material in identified areasWhere the management aim is suppression of invasive fish populations, then removals can provide an effective short-term measure. Its long-term effectiveness is, however, reduced substantially if the remaining fish exhibit compensatory responses, such as increased survival, growth and fecundity.Correspondingly, long-term population suppression using removals is likely to require sustained management efforts, potentially accruing high resource costs (Davies and Britton, 2015).

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is almost impossibleAccording to Godard (2015b), Ameirus melas and Ameiurus nebulosus are difficult/costly to control

Ameiurus melas (Black bullhead)Control of A. melas populations within lentic environments could be possible.

The application of trapping and electric fishing to controlling black bullhead Ameiurus melas was relatively effective in a French lake as no compensatory responses were recorded. In contrast, compensatory responses were detected in A. melas populations elsewhere following mass removals. (Cucherousset et al, 2006b).

In England rotenone was used to eradicate the only known wild population of black bullhead catfish in England (Essex) (Brazier, 2015). Other mechanism is mechanical removal by fishing/angling; the species is reportedly easy to catch.

Ameiurus nebulosus (Brown bullhead)Physical control should involve, if possible, physical isolation of introduced populations, which may require physical (e.g., block nets) or electrical barriers.Thus, Where the management aim is suppression of invasive fish populations, then removals can provide an effective short-term measure.

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Its long-term effectiveness is, however, reduced substantially if the remaining fish exhibit compensatory responses, such as increased survival, growth and fecundity. Correspondingly, long-term population suppression using removals is likely to require sustained management efforts, potentially accruing high resource costs (Davies and Britton, 2015).

Control of A. melas populations within lentic environments is possible. The results of Louette and Declerck (2006) study on “Assessment and control of non-indigenous brown bullhead (Ameiurus nebulosus) populations using fyke nets in shallow ponds” suggest that double fyke nets, when combined with the mark-recapture technique, are a very useful tool for the efficient and reliable assessment of brown bullhead populations. The results of the study also suggest that double fyke nets may potentially be a cost-effective tool for the mass removal of non-indigenous brown bullhead populations. This could be applied also for other species of Ameiurus. Other method that worked was using a piscicide to extirpate an established stillwater population from England in 2014 (see 2.14 for further information)..

Ameiurus melas

In a fishery in North London the black bullhead have spread, the risk to the wider environment was significant; so a piscicide based eradication was carried out by the National Fisheries Services Virtual

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Non-native Species Management Team in May 2014. It seems they managed to remove the only known population of the highly invasive black bullhead from a fishery in Essex, England (https://marinescience.blog.gov.uk/2015/08/07/eradicating-black-bullhead-catfish/).

In England it has been completed an eradication of the only known wild population of black bullhead catfish in England (Essex). In a one day operation, specially trained officers treated the lake with rotenone, a chemical that targets fish, whilst causing little harm to other aquatic life. The work was successful in removing this highly invasive and damaging species. The lake and its native fish had been suffering the impacts of these catfish for some time and angling club members had noticed a drastic decline in the performance of the fishery; including the deterioration in the growth rate, size of native fish, reduced catch rate and the black bullhead as a nuisance. The club contacted the Environment Agency fisheries department and the operation to remove the catfish was planned.

Eradication through piscicides, such as rotenone or through mechanical removal by fishing/angling; the species is reportedly easy to catch. Mass removal has also been considered as a possibility (CABI, 2015a)

Ameiurus nebulosus

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Eradication may involve the use of chemical agents (e.g., rotenone) to induce mortality within introduced populations, although such methods should be evaluated for their potential effects on non-target fishes. Other measures (e.g., physical removal using fish sampling gears: fyke nets, seines, boat and backpack electrofishers) may also be effective.Physical control should involve, if possible, physical isolation of introduced populations, which may require physical (e.g., block nets) or electrical barriers.

Biological control of adult A. nebulosus is unlikely given the paucity of natural predators within the native range, although juveniles may be predated upon by certain large-bodied fishes (e.g., Esox spp. within native range) (CABI, 2015b).

Ameirus melas and Ameiurus nebulosus is difficult/costly to control (CABI, 2015a).

Ameiurus natalis

Public awareness is essential for this species to prevent misidentification of this species with A. melas and A. nebulosus. Public awareness is important to prevent establishment of new populations and to prevent further illegal introductions of this species.

Open season fishing for A. natalis is possible and fish can be readily caught using a regular line, by

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electrofishing or a beach seine. Targeted removal of the young-of-the-year when in tight schools would limit the impact this species has on the habitat.

Chemicals such as rotenone can be applied at a concentration of three parts per million to remove A. natalis but will also eliminate any other fish which you may want to protect. (CABI, 2009).

2.4. Based on the answers to questions on the potential for establishment and spread in Europe, define the area endangered by the organism.

[Most of Europe, ]

high At least 2two species of the genus Ameiurus are established in Europe, A. nebulosus and A. melas, the latter being present in almost all countries. Other 2two species (A. natalis and A. catus) have been eventually recorded. The actual occupied area it seems to be minimal, but there is no information to estimate the endangered area for these two species.See answers to questions 5 and 6 of EU CHAPPEAU

2.5. What proportion (%) of the area/habitat suitable for establishment (i.e. those parts of Europe were the species could establish), if any, has already been colonised by the organism?

10-33-67 low It’s very difficult to answer this question with the current and dispersed data about the distribution of the established species in Europe. Given the high proportion of countries where two Ameiurus species (A. melas and A nebulosus) are confirmed as established, as well as the possible bad ecological conditions of the habitats where it is foundopportunistic and tolerant character of these species, it is considered that it may be of the order of that proportion.

We estimate that 10-33% of the habitat suitable for establishment is already colonised by the two species.

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2.6. What proportion (%) of the area/habitat suitable for establishment, if any, do you expect to have been invaded by the organism five years from now (including any current presence)?

10-33-67 low Given the recent colonization of the species and the dispersal rate of the A. melas and A. nebulosus that was medium in Continental, Atlantic and Boreal zones (Secretariat of NOBANIS, 2012), it is estimated that its colonization in five -years from now may be of this ordercould increase at some extant, at least for A. melas and A. neboulosus. The life-history traits of A. melas and A. nebulosus and their plasticity are similar to other successful invaders, which will facilitate range expansion for this species. It is supposed that, if no measures will be taken, and other new Ameiurus species enter, they could have the same success as invaders.in Europe.. Wide environmental tolerances and the fact that suitable habitats are present and widely distributed in the Risk Assessment Area, will also allow a greater number of water bodies to provide suitable habitat for Ameiurus.

2.7. What other timeframe (in years) would be appropriate to estimate any significant further spread of the organism in Europe? (Please comment on why this timeframe is chosen.)

20 low There is not a follow-up of its expansion, but Considering the conditions of expansion in which the species occurs and the effects of Climate Change, this can be significant in this period.

As included in the article Fishes of the genus Ameiurus (Ictaluridae, Siluriformes) in the Transcarpathian water bodies (Movchan et al, 2014) their expansion in Tisza took place subsequently after almost 50 years, and now there is a new destabilization (deterioration and redistribution) in some ichthyocenoses under the influence of dangerous and aggressive A. nebulosus and A. melas.

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A. nebulosus gradually became a “victim” of A. melas.

In the case of A. natalis its occurrence in Italy was confirmed in 1988 (Welcomme). So, only thirteen years later the species is confirmed as already established. (Elvira, 2001).

It is to be noted that nowadays the aquatic ecosystems are subject to more deterioration, eutrophication and loss of biodiversity that transform habitats in more suitable for Ameiurus spp.

As included in the article Fishes of the genus Ameiurus (Ictaluridae, Siluriformes) in the Transcarpathian water bodies (Movchan et al, 2014), their expansion in Tisza took place subsequently after almost 50 years.

In the case of A. natalis its occurrence in Italy was confirmed in 1988 (Welcomme, 1988). So, only thirteen years later the species is confirmed as already established (Elvira, 2001).

In Spain (Dana et al., 2016) cited the arrival of A.melas at Majalberraque stream probably due to the natural dispersion that takes advantage of the connection of the rice paddy system and its network of canals with the Guadalquivir. The locality of the Brazo del Este cited by García-de Lomas et al. (2009) is more than 20 kilometers downstream of that, which confirms its dispersion on the Guadalquivir River. It is also very likely that the species is

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much more widespread in the province of Seville.2.8. In this timeframe what proportion (%) of the endangered area/habitat (including any currently occupied areas/habitats) is likely to have been invaded by this organism?

10-33 low ThereIt is no information about the endangered areas/habitats occupied by the species,difficult to answer this question but given the endangered situation of the habitats in the river basins in Europe and the history of invasion of A. melas and A. neboulosus, it is estimated that in 20 years from now it could be of the order of this proportion.

2.9. Estimate the overall potential for future spread for this organism in Europe (using the comment box to indicate any key issues).

high medium As compiled in the document Status of Non-Indigenous Fish Species in the Balaton Catchment (http://www.eulakes.eu/upload/eulakes/gestionedocumentale/output%205.2.1%20-%20lake%20Balaton_effects%20of%20climate%20change%20on%20new%20species_784_2181.pdf) the species expanded relative slowly, however nowadays A. nebulosus and A. melas are the most widespread North American ictalurid catfish in Europe (Pedicillo, 2008). The expansion was human helped in some cases, for example A. melas was imported to Hungary from Italy in 1980 (Harka, 1997). In other situations, a slow, self – managed spreading was observed: for example in Spain_ first recorded in 1984 (Elvira 1984) and Portugal- first recorded in 2002 (Gante and Santos, 2002). The bullheads are tolerant of the harsh water conditions (eg. water pollution, low dissolved oxygen levels), omnivorous, aggressive, has parental care and prolonged reproduction period (Braig and Johnson, 2003, Novomenska and Kovac, 2009, Scott and Crossman, 1973). In Hungarian waters it seems that A. melas outcompete the congener brown

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http://www.eulakes.eu/upload/eulakes/gestionedocumentale/output%205.2.1%20-%20lake%20Balaton_effects%20of%20climate%20change%20on%20new%20species_784_2181.pdf




bullhead (Ameiurus nebulosus) (Harka and Sallai, 2004), this phenomenon is prominent either in the Balaton catchment.

Based on itsthe high flexibility in its life-history traits of A. melas and A. nebulosus, one may assume that the bullheads have a great potential to spread into new environments (NovoneskaNovomeská et al., 2010).

Ameiurus melas is abundant in its native range, capable of securing and ingesting a wide range of food, gregarious, it has a broad native range, it has high reproductive potential, it’s highly adaptable to different environments, it’s invasive in its native range, it is a habitat generalist, it has been proved invasive outside its native range, it’s tolerant of shade (CABI, 2015a)

Ameiurus nebulosus is abundant in its native range, capable of securing and ingesting a wide range of food, fast growing, it has a broad native range, it has high genetic variability, it has high reproductive potential, it’s highly adaptable to different environments, it’s highly mobile locally, it is a habitat generalist, it’s pioneering in disturbed areas,it has been proved invasive outside its native range, it tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc (CABI, 2015b).

Ameiurus natalis is abundant in its native range, capable of securing and ingesting a wide range of

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food, it has a broad native range, it’s highly adaptable to different environments, it’s highly mobile locally, it’s a habitat generalist (CABI, 2009).The expansion was human helped in some cases, in other situations, a slow, self – managed spreading was observed: The bullheads are tolerant of the harsh water conditions (eg. water pollution, low dissolved oxygen levels), omnivorous, aggressive, parental care and prolonged reproduction period are present (Braig and Johnson, 2003, Novomeská and Kovaáč, 2009, Scott and Crossman, 1973).

Pedicillo et al (2008) points out that although the identity of wild European blackbullhead populations is uncertain, this species is the most widespread of the ictalurid species introduced into Europe.

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PROBABILITY OF IMPACTImportant instructions:

When assessing potential future impacts, climate change should not be taken into account. This is done in later questions at the end of the assessment.

Where one type of impact may affect another (e.g. disease may also cause economic impact) the assessor should try to separate the effects (e.g. in this case note the economic impact of disease in the response and comments of the disease question, but do not include them in the economic section).

Note questions 2.10-2.14 relate to economic impact and 2.15-2.21 to environmental impact. Each set of questions starts with the impact elsewhere in the world, then considers impacts in Europe separating known impacts to date (i.e. past and current impacts) from potential future impacts. Key words are in bold for emphasis.

QUESTION RESPONSE CONFIDENCE COMMENTS

2.10. How great is the economic loss caused by the organism within its existing geographic range, including the cost of any current management?

Moderate Low There are no studies where this issue had been calculated.

The Ameirurus spp hasconcerning economic loss. In certain cases of wild establishment, A. melas and A. nebulosus introductions have the potential to hinder local commercial and sport fisheries through competition with target species. (Godard, 2015b; Mandrak, 2009).

Global data are no available but in UK the eradication of Ameiurus melas has been developed in a fishery. (http://www.nonnativespecies.org/news/index.cfm?id=151). A fishery in North London succumbed to this highly efficient invader, and the local angling club had lost one of their best fisheries.Ameiurus melas (Black bullhead)

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The operation to remove the catfish costed approx. £5000.00 (€6356.00) £10,000.00, including manpower costs (APHA, personal comm.).

There is potential that Ameiurus melas can have a negative economic impact on communities as this fish can be a 'nuisance' species taking lines/bait intended for other species. Anglers not targeting this species might therefore move on to black bullhead free waters taking not only the money from recreational fishing but tourism (food, accommodation and transportation) all of which may provide economic opportunities locally (CABI, 2015aGodard, 2015b).

To date, Ameiurus nebulosus (Brown bullhead)Economic impacts resulting from A. nebulosus introductions have not been quantified. In certain cases of wild establishment, A. nebulosus introductions have the potential to hinder local commercial and sport fisheries through competition with target species (CABI, 2015b(Mandrak, 2009).

Van der Veer and Nentwig (2014) don’t find any environmental economic impact of A. melas and A. nebulosus in six environmental and six economic impact categories agriculture, animal production, forestry, human infrastructure, human health and human social life.

2.11. How great is the economic cost of the organism currently in Europe excluding management costs

Unknown To date, economic impacts resulting from Ameiurus introductions have not been

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(include any past costs in your response)? quantified. In certain cases of wild establishment, A. nebulosus and A. melas introductions have the potential to hinder local commercial and sport fisheries through competition with target species.

For instanceVan der Veer and Nentwig (2014) didn’t find any economic impact of A. melas and A. nebulosus in Europe. Six economic impact categories were analised: agriculture, animal production, forestry, human infrastructure, human health and human social life.

In Great Britain and Ireland (Gallardo and Aldridge, 2013) A. melas was included in the list of 12 aquatic species potentially causing greatest ecological and economic harm in Great Britain and Ireland (Gallardo and Aldridge, 2013)..

Species with high potential impact on water quality as Ameiurus melas are not necessarily those associated with monetary costs (e.g. Neovison vison) with could be more conspicuous for general public.A fishery in North London had succumbed to this highly efficient invader, A. melas, and the local angling club had lost one of their best fisheries (Brazier, 2015).

More information is needed in order to conclude how great the economic cost of A. melas and A. nebulosus in Europe is.

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2.12. How great is the economic cost of the organism likely to be in the future in Europe excluding management costs?

Unknown Further studies should be undertaken in relation with water quality.

In the Alqueva Dam their evaluation of both environmental management programmes, and various studies from the region, brought to light a number of underevaluated impacts. It was identified that the transition from flowing to standing water catalyzed the emergence of invasive fish and plant species (Ameiurus melas, Eichhornia crassipes, etc.). - http://ced.berkeley.edu/downloads/research/AlquevaReportLA205-2015.pdf-

In the absence of data for this species, costs for the control of other species of fish are included in an indicative way:

- Current efforts to control topmouth gudgeon in GB amount to £190,000 over 4 years (http://invasivespeciesireland.com/wp-content/uploads/2010/07/Economic_Impact_Assessment_FINAL_280313.pdf)

- In 2010 alone, the US federal government committed $78.5 million in investments to prevent the introduction of Asian carp to the Great Lakes, where they would threaten Great Lakes fisheries and could negatively impact remaining populations of endangered or threatened aquatic species.

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http://invasivespeciesireland.com/wp-content/uploads/2010/07/Economic_Impact_Assessment_FINAL_280313.pdf



http://ced.berkeley.edu/downloads/research/AlquevaReportLA205-2015.pdf-

http://ced.berkeley.edu/downloads/research/AlquevaReportLA205-2015.pdf-


(https://www.fws.gov/verobeach/PythonPDF/CostofInvasivesFactSheet.pdf).Minckley (1973) in Fuller and Neilson (2017) reported that A. melas is generally considered a pest in Arizona as it forms large stunted populations that compete with more desirable fishes for space and food. This happens in Europe where it can be a “nuisance” species taking lines /bait intended for other species (Huble, 2011). Currently, there is no technical or scientifical basis to estimate this cost. Among other subjects, further studies should be undertaken in relation with water quality.

2.13. How great are the economic costs associated with managing this organism currently in Europe (include any past costs in your response)?

Unknown There are no published studies, about the economic costs associated with managing this organism other than the work undertaken by the UK Environment Agency’s Non-native Species Eradication Team (See Comment for Question 1.21 and 2.14)

The results of Louette and Declerck (2006) study on Assessment and control of non-indigenous brown bullhead (Ameiurus nebulosus) populations using fyke nets in shallow ponds suggest that double fyke nets, when combined with the mark-recapture technique, are a very useful tool for the efficient and reliable assessment of brown bullhead populations. The results of the study also suggest that double fyke nets may potentially be a cost-effective tool for the mass removal of non-indigenous brown bullhead populations. This could

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be applied also for other species of Ameiurus.

As included in the “Ecological risk assessment of non-indigenous species in Lake Balaton: a pilot study” (http://eulakes-model.eu/media/files/ecological-risk-assessment-of-non-indigenous-species-in-lake-balaton.pdf) the FISK assessments were undertaken independently by the three co-authors. Each person calculated the total FISK scores for each species. Altogether nine species (Carassius gibelio; Perccottus glenii; Anguilla anguilla; Lepomis gibbosus; Neogobius fluviatilis; Gambusia holbrooki; Hypophthalmichtys molitrix x nobilis;about Ameiurus melas; Pseudorasbora parva). 5 of the 9 examined fish species (55.6%) – among of them Ameiurus melas- received FISK scores ≥19 (scores between 24 and 33), and thus could be classified as species posing high risk to become abundant in the Balaton catchment. For 6 species (among of them Ameiurus melas), effect on the Catchments seemed to be more significant, which could mean the hardly quantifiable costs of ecosystem services (Farber et al., 2002)..

Ameiurus melas (Black bullhead):

Global data are no available but in UK the eradication of Ameiurus melas has been developed in a fishery. (GB non-native Species Secretariat, 2014). The operation to remove the catfish costed approx. £5000.00 (€6356.00) £10,000.00,

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including manpower costs (APHA, personal comm.) but the local angling club lost one of their best fisheries.

Other examples:

In the absence of data for these species, costs for the control of other species of fish are included in an indicative way:

- Current efforts to control topmouth gudgeon Pseudorasbora parva in GB accounted for over £190,000 in 4 years (Kelly et al., 2010).

- In 2010 alone, the US federal government committed $78.5 million in investments to prevent the introduction of Asian carp to the Great Lakes, where they would threaten Great Lakes fisheries and could negatively impact remaining populations of endangered or threatened aquatic species (U.S. Fish & Wildlife Service, 2012).

2.14. How great are the economic costs associated with managing this organism likely to be in the future in Europe?

Unknown There are no specific studies.

Population suppression, or even removal with sufficient effort, According to Godard (2015b), Ameiurus melas and Ameiurus nebulosus are difficult/costly to control although it is possible through bio-manipulation of A. melas populations using fyke nets (Louette and Declerck, 2006)as described inGB non-native Species Secretariat (2014).

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2.15. How important is environmental harm caused by the organism within its existing geographic range excluding Europe?

major medium The ecological effects of A. melas seem potentially close to the A. nebulous.

Information about A. melas, A. nebulosus, A. natalis and A. catus is presented in this section although is very limited.

Moore et al (2010) in the review of species on the grey list in the strategic approach for the management of ornamental fish in Australia included the precautionary approach in the risk assessment related to the unavailability of information about impact on habitat and on other species. In this study, all Ameiurus species are catalogated as “high risk”.

Ameiurus melas (Black bullhead)Godard (2015b) mentions impacts such as competition (for food and/or space) with native species, and predation of native species have been reported. This species is normally considered a detritivore but recent studies suggest its diet could include fish and fish eggs. The same author points out that the main mechanism for A. melas is predation. The main outcomes are: damaged ecosystem services, ecosystem change/habitat alteration, modification of natural benthic communities, and modification of nutrient regime, negatively impacts, aquaculture/fisheries, reduced native biodiversity, threat to /loss of endangered species and threat to / loss of native species.

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Introduced Black Bullhead eatpray on endangered humpback chubs Gila cypha in the Little Colorado River, and may exert a major negative effect on the population there (Marsh and Douglas 1997. In. (Minckley (1973in Fuller P. and Neilson M., 2017). Minckley (1973), in Fuller P. and Neilson M. (, 2017) reported that this species is generally considered a pest in Arizona as it forms large stunted populations that compete with more desirable fishes for space and food. Black Bullheads are voracious predators of newly hatched gamefish (Whitmore, 1997. In Fuller P. and Neilson M., 2017).. Introduced predatory fishes, including the Black Bullhead, are likely at least partially responsible for the decline of the Chiricahua leopard frog Rana chiricahuensis in southeastern Arizona (Rosen et al. 1995),, and have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Hughes and Herlihy 2012. In Fuller P. and Neilson M.,, 2017).

Van der Veer and Nentwig (2015) find some environmental impacts in herbivory, predation, competition, disease transmission, and ecosystem alteration) of A. melas and A. nebulosus mainly in competition, predation, ecosystem alteration, herbivory and disease transmission.

CABI (2015a) points out the following impacts of Ameiurus melas. The main mechanism is

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predation. The main outcomes are: conflict, damaged ecosystem services, ecosystem change/ abitat alteration, modification of natural benthic communities, modification of nutrient regime, negatively impacts, aquaculture/fisheries, reduced native biodiversity, threat to/loss of endangered species and threat to/ loss of native species.

CABI (2015a) points out the following impacts of Ameiurus nebulosus: The main mechanisms are competition –Ameiurus nebulosus (Brown bullhead)Mandrak (2009) pointed out that the main mechanism for A. nebulosus is competition: monopolizing resources, interaction with other invasive species and predation. The main outcomes are altered trophic level, damaged ecosystem services, ecosystem change/habitat alteration, and modification of natural benthic communities, negatively impacts aquaculture/fisheries, reduced native, biodiversity, threat to / loss of endangered species and threat to / loss of native species.

Chile reported adverse effects on native fish communities following its establishment (Mandrak, 2009).

Brown Bullhead has been shown to reduce the abundanceand diversity of native prey species in several Pacific Northwest rivers Fuller and Neilson, 2017b).

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Feeds on a wide variety of items including snails, freshwater crayfish, fish eggs, worms, insects (adults and larvae), fish and algae.Global Invasive Species (2006) doesn’t find any hard evidence of environmental impacts caused by these brown bullheads, although there is some concern that may negatively affect trout fisheries, freshwater crayfish and eels.

White Catfish were apparently responsible for the disappearance of Sacramento perch Archoplites interruptus in Thurston Lake, California (McCarraher and Gregory 1970. In: Fuller P. and Neilson M. 2017)CABI (2009) points The main prey of adult brown bull head in Lake Taupo, New Zealand is freshwater crayfish (Global Invasive Species, 2006).

Ameiurus natalis (Yellow bullhead)Godard (2015a) pointed out the following impacts of Ameiurus nativisnatalis: Ecosystem change/ habitat alteration, modification of natural benthic communities, negatively impacts aquaculture/fisheries, negatively impacts tourism, reduced amenity values, reduced native biodiversity and threat to/ loss of native species.

A. natalis has a negative impact on native species decreasing both the abundance and diversity of species in an area. Impact of Introduction: Introduced predatory fishes, including the Yellow

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Bullhead, are likely at least partially responsible for the decline of the Chiricahua leopard frog Rana chiricahuensis in southeastern Arizona, and have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Fuller and Neilson, 2017c).

Ameiurus catus (White catfish) was apparently responsible for the disappearance of Sacramento perch Archoplites interruptus in Thurston Lake, California (McCarraher and Gregory 1970.

2.16. How important is the impact of the organism on biodiversity (e.g. decline in native species, changes in native species communities, hybridisation) currently in Europe (include any past impact in your response)?

major medium Ameiurus Information about A. melas, A. nebulosus and A. natalis is partially responsible forincluded in this point. There is a lack of information about the declineother species recorded in Europe: A catus.

Species of Ameiurus genus is likely to pose a significant genetic risk through hybridisation/introgression with exotic species. Ictalurus punctatus, a species of the Chiricahua leopard frog (Rana chiricahuensis) in southeastern Arizona (Rosensame family, introduced in several European countries, has been known to mate with brown bullhead (Ameiurus nebulosus), yellow bullhead (Ameiurus natalis), and black bullhead (Ameiurus melas), resulting in a variety of hybrid catfish (Florida Museum, 2017). Brown bullheads (Ameiurus nebulosus) are known to hybridize naturally with closely related black (Ameiurus melas) and yellow bullhead (Ameiurus natalis)

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species (Hunnicutt et al., 1995; Fuller et al., 19992005).

Ameiurus melas (Black bullhead) may affect the native fauna in three distinct ways. First, it may prey directly on some species, therefore reducing the amount of available prey for native predators. Second, black bullhead may have an indirect effect by generating turbidity that can modify the feeding efficiency of visual predators. Third, due to their high local abundance, black bullhead behaviour may interfere with accompanying species and hence negatively affect the behavioural feeding phases of native predators and the anti-predator behaviour of native prey (Kreutzenberger et al., 2008).

Black bullheads tend to be found in high local abundance, their behaviour could therefore interfere with accompanying species and negatively affect the behavior of native predators and prey (Godard, 2015b). For example, a series of experiments has shown that the presence of this A. melas reduces the predation success of Esox lucius on minnows, not by actively competing with pike for minnows, but simply by interfering with the normal behaviour of pike. Infection levels by parasites normally transmitted trophically from minnows to pike may be reduced as a consequence. However, since pike switch to other food items, they may be exposed to other parasites transmitted via these different preys (Poulin et al., 2011).

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Ameiurus nebulosus has negative effects on native fish species by feeding on the bottom fauna, small fishes, fish larvae, and roe (Pujin and Sotirov, 1966).The principal effects on biodiversity of A. melas are: competition (for food and/or space) with native species, and predation of native species including fish and fish eggs (van der Veer and Nentwig, 2014; Godard, 2015b).

A. melas and pumpkinseeds can extirpate a stickleback population in 2 years (Cannings and Ptolemy 1998). The catfish feeds on the eggs of the stickleback (Backhouse, 2000).

Four of the European countries where Ameiurus melas has been introduced, four of themhave reported impacts on the ecological community due to dominance, three reported bioaccumulation of pollutants, two reported impacts due to competition (for food or/and for space) with native species, and one reported impacts due to predation on native species. There may also be impacts (direct or indirect) through increased turbidity related to reduced macrophyte growth and reduced stability of substrates (Hubble, 2011). A. melas can reach populations as high as 227 kg/ha; individuals have been found with large amounts of vegetation in their stomachs (NatureServe, 2006).

The bullheads should be considered generalist,

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foraging on the most abundant and available prey. The impact is because of the competition, due to the coincidences with the preys used by some native species, predation over native species and habitat degradation (Leunda et al, 2008).

As compiled in CABI (http://www.cabi.org/isc/), impacts produced by A.melas, A. nebulosus and A. natalis such as competition (for food and/or space) with native species, and predation of native species have been reported. In the same way, A. natalis are adaptive opportunistic and omnivores eaters, consuming whatever is edible within their environment and has a negative impact on native species, decreasing both the abundance and diversity of species in an area (Hughes and Herlihy, 2012).

Ameiurus spp. are normally considered detritivores but recent studies suggest their diet include fish and fish eggs (Boet, 1980). Therefore, this species might be reducing the amount of available prey for native predators. Due to the generalist and opportunistic feeding habits of Ameiurus species, Leunda et al. (2008) analyzed data from Spain and Portugal indicating impacts of A. melas on a wide range of potential prey species as well as impacts through competition. In this study, black bullheads consumed plant material, terrestrial prey and co-occurring fish species (native or exotic), taking the most abundant and available prey.

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A. nataslis is partially responsible for the decline of the Chiricahua leopard frog (Rana chiricahuensis) in southeastern Arizona (Rosen et al., 1995; Fuller et al., 1999).

Although A. nebulosus is not considered a quarantined pest, several countries Switzerland (Wittenberg, 2005); Poland (FAO, 1997); Chile (Welcomme, 1988)) reported adverse effects on native fish communities following its establishment.

Ruiz-Navarro et al. (2014) demonstrated that native fish species play an important role in the diet of A. melas in their invaded range (England), constituting ~30% of food items ingested.

Out of the 37 fish species introduced to Spain, 31 are freshwater species with the greatest potential for ecological impact attributed to black bullhead Ameiurus melas (Rafinesque, 1820) (42 % of all introductions worldwide, n=21) followed by topmouth gudgeon Pseudorasbora parva (Temminck and Schlegel, 1846) (37% of all introductions worldwide, n=35) (Gozlan, 2010).

Due to the generalist and opportunistic feeding habits of this species, Leunda et al. (2008) analysed data from Spain and Portugal indicating impacts on a wide range of potential prey species as well as impacts through competition. In this study, black bullheads consumed plant material, terrestrial prey

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and co-occurring fish species (native or exotic), taking the most abundant and available prey. Therefore, this species might be reducing the amount of available prey for native predators. Leunda et al (2008) study results suggest that the black bullhead could be negatively affecting native ichthyofauna in two ways. First, the results showed that black bullheads are preying on native fish species such as B. graellsii, P. miegii and G. lozanoi. Even if only fish bony remains (e.g. scales, opercula, cleithra and pharyngeal arches) were identified in black bullhead stomachs, egg predation could not be excluded. Probably, egg predation was not detected because of rapid digestion. Secondly, this study showed that the diet composition of black bullhead is similar to the diet described for some co-occurring Iberian native species. Taking into account black bullhead’s voracity and aggressive behaviour, the diet similarity might lead to an unfavourable competition for the same food resources, subsequently, displacing native fishes to suboptimal food resources.

A. melas can reach populations as high as 227 kg/ha; individuals have been found with large amounts of vegetation in their stomachs (NatureServe 2006).

A. melas in small lakes, for example, on Lasqueti I. This species and pumpkinseeds can extirpate a stickleback population in 2 years (Cannings and

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Ptolemy 1998). The catfish feeds on the eggs of the stickleback (Backhouse 2000).

The Ameiurus species have similar nutrition habits, eating benthic organisms such as molluscs, immature insects, leeches, crustaceans, worms, algae, plant material, fishes and fish eggs (Scott and Crossman, 1973), so we can affirm that the impact on the environment is important, especially on the native species.

Ameiurus melas

The presence of A. melas in a lagoon in Zamora (Spain) is considered the cause of decline of Pelodytes punctatus (the common parsley frog) and Discoglossus galganoi (Iberian painted frog) (MAPAMA, 2013).

In the Slovak part of the middle Danube, invasive species of fishes, especially two species of gobies (Neogobius melanostomus and Neogobius kessleri), topmouth gudgeon Pseudorasbora parva and black bullhead Ameiurus melas, have become a serious problem for native fish communities. Small benthic native species, e.g. bullhead Cottus gobio, white‐finned gudgeon Gobio albipinnatus and stone loach B. barbatula, virtually disappeared from the local fish communities. The current list of invasive species of fishes in Slovakia contains nine species (A. melas, C. gibelio, pumpkinseed Lepomis gibbosus, monkey goby Neogobius fluviatilis, racer

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goby Neogobius gymnotrachelus, N. kessleri, N. melanostomus, Amur sleeper Perccottus glenii and P. parva) (Novomeska and Kovac, (Novomeská et al., 2016).)

Ameiurus nebulosus (Brown bullhead)Ameiurus nebulosus is a generalist omnivore, feeding mostly at night and eating benthic organisms that occur frequently within freshwaters: waste, molluscs, immature insects, terrestrial insects, leeches, crustaceans, worms, algae, plant material, fishes and fish eggs. Young (30-60 mm total length) prefer chironomid larvae, ostracods, amphipods, mayflies and other small aquatic invertebrates (Mandrak, 2009).

Ameiurus nebulosus has negative effects on native fish species by feeding on the bottom fauna, small fishes, fish larvae, and roe (Pujin and Sotirov, 1966).CABI (2015a) remarks on the impact on Gila cypha and Rana chiricahuensis populations. According to Marsh and Douglas (1997), introduced A. melas feed on endangered humpback chub, Gila cypha, in the Little Colorado River (USA) and may exert a negative impact on the population there

Also CABI (2015a) mentions impacts such as competition (for food and/or space) with native species, and predation of native species have been reported. This species is normally considered a detritivore but recent studies suggest its diet could

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include fish and fish eggs (Boet, 1980). Minckley (1973) reported that A. melas is considered a pest in Arizona as it forms large populations which compete with more desirable fishes for space and food. They are also voracious predators of newly hatched gamefish (Whitmore, 1997). According to Rosen et al. (1995), introduced predatory fishes, including A. melas, are probably partially responsible for the decline of the Chiricahua leopard frog (Rana chiricahuensis) in south-eastern Arizona. Black bullhead may also have an indirect effect by increasing turbidity (Braig and Johnson, 2003), potentially modifying the feeding efficiency of visual predators (Reid et al., 1999; Utne-Palm, 2002). Black bullheads tend to be found in high local abundance, their behaviour could therefore interfere with accompanying species and negatively affect the behavior of native predators and prey. “

The presence of A. melas in a lagoon in Zamora (Spain) is considered the cause ot the decline of Pelodytes punctatus and Discoglossus galganoi (MAGRAMA, 2016).

Black bullhead may therefore affect the native fauna in three distinct ways. First, it may prey directly on some species, therefore reducing the amount of available prey for native predators. Second, black bullhead may have an indirect effect by generating turbidity that can modify the feeding efficiency of visual predators. Third, due to their

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high local abundance, black bullhead behaviour may interfere with accompanying species and hence negatively affect the behavioural feeding phases of native predators and the anti-predator behaviour of native prey (Kreutzenberger et al., 2008).

These sorts of indirect effects on native freshwater animals have been reported following the introduction of non-native invasive species. For instance, the black bullhead Ameiurus melas Rafinesque, an ictalurid catfish native to North America, has become one of the most successful exotic fish in European freshwater ecosystems. A series of experiments has shown that the presence of this invader reduces the predation success of Esox lucius on minnows, not by actively competing with pike for minnows, but simply by interfering with the normal behaviour of pike. Infection levels by parasites normally transmitted trophically from minnows to pike may be reduced as a consequence. However, since pike switch to other food items, they may be exposed to other parasites transmitted via these different preys (Poulin et al., 2011).

Ameirus nebulosus

CABI (2015b

Mandrak (2009) remarks on the impact on Gasterosteus populations. Brown bullheadbullheads are scavengers as well as

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predators, locating their prey in the substrate through the use of their sensory barbels (Global Invasive Species, 2006).

As an adaptation for prey capture within turbid waters, the species uses oral barbels to sense food items. A. nebulosus is a generalist omnivore, feeding mostly at night and eating benthic organisms that occur frequently within freshwaters: waste, molluscs, immature insects, terrestrial insects, leeches, crustaceans, worms, algae, plant material, fishes and fish eggs. Young (30-60 mm total length) prefer chironomid larvae, ostracods, amphipods, mayflies and other small aquatic invertebrates

Ameiurus nebulosus introductions may lead to competition for food or space and predation on small fishes, invertebrates or other small food items. Of particular concern is the potential for altered energetic pathways within recipient ecosystems, given their omnivorous diet and a body structure that precludes predation from but all of the largest fishes.

This omnivorous fish species can form very dense populations and is able to dominate freshwater fish communities. Diet of large-sized bullheads has been found to consist almost exclusively of juvenile fishes (Anseeuw et al., 2007).

For those reasons A. nebulosus is considered a pest

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in Poland, and fisheries legislation forbids release of this species into the wild. (Nowak et al, 2010).

Although A. nebulosus is not considered a quarantined pest, several countries like Switzerland (Wittenberg, 2005) and Poland (FAO, 1997) reported adverse effects on native fish communities following its establishment.

van der Veer and Nentwig (2014) calculated the impact points obtained by the generic impact scoring system in six environmental impact categories for A. melas and A. nebulosus (Herbivory (He) Predation (P); Competition (C); Transmission of diseases (Td); Hybridization (Hy); Ecosystem alteration (E).

Comparing with the mean score for the 40 alien established fish species, five of the scores for environmental impact (except Hybridization) were greater (see graphic below) in the case of A. melas and A. nebulosus.

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According to this study, the Goldfish C. auratus/C. gibelio (25.4 impact points) had the highest impact score of all alien fish species, followed by topmouth gudgeon Pseudorasbora parva (15.4 impact points), grass carp Ctenopharyngodon idella (14.5 impact points), brook trout Salvelinus fontinalis (13.6 impact points) and the guppy Poecilia reticulata (10.2 impact points), followed by Ameiurus melas with 9,9 points, while A. nebulosus is considered to have a lower impact with 7,3 points (environmental and economic impact).

Ameiurus natalis (Yellow bullhead)The yellow bullhead was largely introduced in other North American countries where it is not-native. At least one country reports adverse ecological impact after introduction of Ameiurus natalis in North America (Froese and Pauly, 2016).

Ameiurus natalis is known to eat minnows, crayfish, insects, and larvae of insects, aquatic invertebrates, worms and more aquatic vegetation (macroalgae) As an adaptation for prey capture

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within turbid waters, the species uses oral barbels to sense food items. A. nebulosus is a generalist omnivore, feeding mostly at night and eating benthic organisms that occur frequently within freshwaters: waste, molluscs, immature insects, terrestrial insects, leeches, crustaceans, worms, algae, plant material, fishes and fish eggs (Scott and Crossman, 1973). Young (30-60 mm total length) prefer chironomid larvae, ostracods, amphipods, mayflies and other small aquatic invertebrates (Scott and Crossman, 1973) (CABI, 2015b).than the other bullheads.

Feeds on a wide variety of items including snails, freshwater crayfish, fish eggs, worms, insects (adults and larvae), fish and algae. The main prey of adult brown bull head in Lake Taupo, New Zealand are freshwater crayfish (global Invasive Species, 2006).

Nonnative predators, including Brown Bullhead, have been shown to reduce the abundanceand diversity of native prey species in several Pacific Northwest rivers Fuller and Neilson, 2017b).

A. natalis has a negative impact on native species decreasing both the abundance and diversity of species in an area. A. nataslis is partially responsible for the decline of the Chiricahua leopard frog (Rana chiricahuensis) in southeastern Arizona.

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Since A. natalis have few predators, they are able to survive harsh environmental conditions and have a high reproductive rate. They are often the only species in small, shallow lakes and can quickly overpopulate these bodies of water (CABI, 2009Godard, 2015a).

Impact of Introduction: Introduced predatory fishes, including the Yellow Bullhead, are likely at least partially responsible for the decline of the Chiricahua leopard frog Rana chiricahuensis in southeastern Arizona, and have been shown to reduce the abundance and diversity of native prey species in several PacificNorthwest rivers (Fuller and Neilson, 2017c).

Ameiurus catus is apparently responsible for the disappearance of Sacramento perch Archoplites interruptus in Thurston Lake, California (Fuller and Neilson, 2017d).

2.17. How important is the impact of the organism on biodiversity likely to be in the future in Europe?

major medium The impact that occurs mostly on aquatic ecosystems is very high, so the effect of invasive species such as Ameiurus spp. is one factor more to add on the loss of native biodiversity.

Negative impact such as competition (for food and/or space) and predation of native species have been reported to all analyzed species of Ameiurus. (http://www.cabi.org/isc/).

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http://www.cabi.org/isc/


Changes in water transparency and increase of turbidity could affect all the ecosystems where Ameiurus spp. are present.

2.18. How important is alteration of ecosystem function (e.g. habitat change, nutrient cycling, trophic interactions), including losses to ecosystem services, caused by the organism currently in Europe (include any past impact in your response)?

majormoderate

highmedium

Of particular concern is the potential for altered energetic pathways within recipient ecosystems, given their omnivorous diet and a body structure that precludes predation from but all of the largest fishes.Some biological variables as the feeding behaviour and trophic status of at least four Ameiurus species (A. melas, A. nebulosus, A. natalis and A. catus) are responsible for the decline of native species (and consequently impact on the fisheries) and the muddying of the water which may alter habitats, nutrient cycling and trophic interacions.

Ameiurus melas (Black bullhead)Kreutzenberger et al. (2008) describes three distinct ways which can explain the effect of A. melas on native fauna and consequently on fisheries. Impact on fishing as a cultural ecosystem service is demonstrated with the exemple of the fishery in North London that succumbed to this highly efficient invader, and the local angling club had lost one of their best fisheries.

According to Kreutzenberger et al. (2008), it may prey directly on some species, therefore reducing the amount of available prey for native predators. Second, black bullhead may have an indirect effect by generating turbidity that can modify the feeding

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efficiency of visual predators. Then, Ameiurus melas is related to the physic-chemical dimension of water quality: changes in water transparency and increase of turbidity (Braig and Johnson, 2003). There may also be impacts (direct or indirect) through increased turbidity related to reduced macrophyte growth and reduced stability of substrates (Hubble, 2011). Third, due to their high local abundance, black bullhead behaviour may interfere with accompanying species and hence negatively affect the behavioural feeding phases of native predators and the anti-predator behaviour of native prey.

They are unpopular, because they form dense stunted populations. Their adaptability and ferocious feeding behaviour make them a grave threat to the native fish and amphibian fauna. In places, they have built up huge populations and replaced native fish species, probably through competition for food (FOEN, 2006).

The loss of species, as well as the transformation of the habitat and modification of its natural conditions, such as turbidity increased, supposes an important effect on the function of ecosystems.

Impact on fishing as a cultural ecosystem service is demonstrated: A fishery in North London succumbed to this highly efficient invader, and the local angling club had lost one of their best fisheries.

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As included in the “Ecological risk assessment of non-indigenous species in Lake Balaton: a pilot study” (http://eulakes-model.eu/media/files/ecological-risk-assessment-of-non-indigenous-species-in-lake-balaton.pdf) the FISK assessments were undertaken independently by the three co-authors. Each person calculated the total FISK scores for each species. Altogether nine species (Carassius gibelio; Perccottus glenii; Anguilla anguilla; Lepomis gibbosus; Neogobius fluviatilis; Gambusia holbrooki; Hypophthalmichtys molitrix x nobilis; Ameiurus melas; Pseudorasbora parva). 5 of the 9 examined fish species (55.6%) – among of them Ameiurus melas- received FISK scores ≥19 (scores between 24 and 33), and thus could be classified as species posing high risk to become abundant in the Balaton catchment. For 6 species (among of them Ameiurus melas), effect on the Catchments seemed to be more significant, which could mean the hardly quantifiable costs of ecosystem services (Farber et al., 2002).

In France the results from Cucherousset et al. (2006) study suggest that the invasion of A. melas has been facilitated by the expansion of reed beds associated with the diminution of agricultural pressure in recent decades. This study represents an unusual example where human activities can have had an unexpected effect by facilitating an invasive fish species. Furthermore, A. melas abundance

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increases when decreasing water depth (Brown et al. 1999) and the production of a large amount of litter by the reed beds might favour A. melas by limiting water depth.

This study examined the distribution and habitat selection of the invasive black bullhead in the ditches and surrounded temporary flooded habitats of an artificial wetland in western France. A multiscale approach was used to quantify patterns of A.melas abundance in relation to physical habitat characteristics in the ditch network. Young-of-the-year (YOY) and adult A. melas largely dominated the local fish assemblage but were highly variable among sites. Although we found evidence for some fine-scale habitat differences for YOY and adult individuals, the abundance of A. melas was positively and consistently related to the dominance of reed beds. Furthermore, A. melas preferentially used reed beds as opposed to marsh meadows during the flooding period. The results from this study suggest that the invasion of A. melas has been facilitated by the expansion of reed beds associated with the diminution of agricultural pressure in recent decades. This study represents an unusual example where human activities can have had an unexpected effect by facilitating an invasive fish species (Cucherousset et al., 2006).

Ameiurus melas is related to the physic-chemical dimension of water quality. Changes in water

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transparency and increase of turbidity (Braig and Johnson, 2003).

Ameiurus species are responsible for the muddying of the water in their search for food which may alter ecosystems and stop other species to feed.

Ameiurus melas

Of the countries where it has been introduced in Europe there may be impacts on habitat (direct or indirect), potentially through increased turbidity related to reduced macrophyte growth and reduced stability of substrates (CABI, 2015).

Black bullhead may also have an indirect effect by increasing turbidity (Braig and Johnson, 2003), potentially modifying the feeding efficiency of visual predators (Reid et al., 1999; Utne-Palm, 2002).

The greater impact of benthivorous fish on turbidity within shallow systems may be an indirect one through the destruction of macrophytes and subsequent destabilization of unconsolidated substrates (Braig et al, 2003)

Ameiurus nebulosus

A. nebulosus (Brown bullhead) may increase physical disturbance within freshwaters due to their benthivorous feeding habits. Although their barbels

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may aid in prey capture, foraging aggressively within substrates may be necessary to dislodge certain benthic prey items, which in-turn can increase turbidity and lead to altered productivity and nutrient cycling. Estimates regarding habitat impacts following A. nebulosus introductions have not been quantified (CABI, 2015Mandrak, 2009).

Of particular concern is the potential for altered energetic pathways within recipient ecosystems, given their omnivorous diet and a body structure that precludes predation of the largest fishes (Mandrak, 2009).

Ameiurus natalis

A. natalis are (Yellow bullhead) is responsible for the muddying of the water in their search for food which may alter ecosystems. It has been suggested that this action makes it difficult for visual predators such as centrarchids to find food. (Godard, 2015a).

Ameiurus catus (White catfish) can be found in sluggish, mud-bottomed pools, open channels, and backwaters of small to large rivers and lakes, and feeds on wide variety of fishes, insects and crustaceans. So it is expected that its alteration of a new ecosystem function is important (Murdy et al, 1997).

2.19. How important is alteration of ecosystem major high Negative effects on aquatic ecosystems are

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function (e.g. habitat change, nutrient cycling, trophic interactions), including losses to ecosystem services, caused by the organism likely to be in Europe in the future?

intensifying as they are suffering transformations by which worsens its evolution in the future.

Both surface and bottom turbidity increased with adult and juvenile black bullhead biomass (Braig and Johnson, 2003). This has been demonstrated to have an impact on the foraging success of native predators, such as the pike Esox lucius (Kreutzenberger et al., 2008)

The Guadalquivir Estuary (Spain) is a highly productive ecosystem that provides permanent habitats for estuarine species as well as playing an important role as breeding and adult-feeding grounds for marine species (Baldó and Drake 2002; González-Gordillo and Rodríguez 2003). Considering the current increase of the A. melas population and its ability to feed voraciously on a variety of prey from small aquatic macroinvertebrates to fish (Leunda et al. 2008), further impacts on estuarine ecosystem function and services may occur but this requires further study (Garcia-de-Lomas et al., 2009).

As described in Vandekerkhove et al. (2013) There is increasing evidence that IAS invasive alien species can adversely affect the structure and functioning of aquatic ecosystems (Kideys, 2002; Krisp and Maier, 2005; Klein and Verlaque, 2008).. Alternatively, a change in structure and functioning may also facilitate the introduction and spread of alien species. A reduction in native

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species richness – for example, caused by hydromorphological changes – may affect the resilience of communities to invasions (Dunstan and Johnson 2006),, or eutrophication may dramatically alter the food-web structure in favour of non-native species. The latter is true for many shallow lakes, where increased nutrient levels have induced a shift from a top-down to a bottom-up regulated food web structure, with reduced control of invasive planktivorous and benthivorous fish (Scheffer 1998)... The effects of IASinvasive alien species and other pressures are likely to reinforce each other, potentially resulting in an invasional meltdown at the water body level (Ricciardi 2001).. At the regional scale, positive feedback mechanisms might explain the observed exponential increase in the numbers of alien species (DAISIE 2009Vandekerkhove et al., 2013).

Garcia-de-Lomas et al. (2009) warn about the occurrence of impacts of the increasing A. melas population on estuarine ecosystem function and services in the Guadalquivir Estuary in Spain. This estuary is a highly productive ecosystem that provides permanent habitats for estuarine species as well as playing an important role as breeding and adult-feeding grounds for marine species.

2.20. How important is decline in conservation status (e.g. sites of nature conservation value, WFD classification) caused by the organism currently in Europe?

major high Ameiurus species live in valuable sites for nature conservation in Europe, for example, Ameiurus melas is found in areas of high value for the conservation of nature, so the loss of biodiversity

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supposes a high decline in the conservation status of these areas. The most valuable species and habitats are threatened.

According to the WFD, the status of all European rivers and streams must be assessed and classified into five predefined levels of ecological status or quality classes (bad, poor, moderate, good and high) based on four biotic elements (diatoms, macroinvertebrates, macrophytes and freshwater fish) (Hermoso et al., 2010). Any decline in native species is related with a poor ecological status, so it has influence in this classification.

Two examples or the presence of A, melas in two sites of nature conservation value are presented:- In Spain, this species is present in the National Park Tablas de Daimiel (http://www.castillalamancha.es/sites/default/files/documentos/paginas/archivos/doc_1_es0000013_0.pdf). (Dirección General de Política Forestal y Espacios Naturales. Junta de Comunidades de Castilla La Mancha, 2015).Its reproduction is also confirmed in the Doñana Natural Area.- In France the species is included in the list of Fish species recorded on the Natura 2000 site of the Lower Valley Doubs - Doubs and Clauge.Clagu (Muséum National d'Histoire Naturelle, 2016)

2.21. How important is decline in conservation status (e.g. sites of nature conservation value, WFD

major high Given what we have comented in previous sections, it can be deduced that the presence of

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classification) caused by the organism likely to be in the future in Europe?

Ameiurus species can impact on key native species and habitats on Natura 2000 Network.

Related to the WFD, a relationship between the abundance and richness of alien species and a bad or poor quality class is observed in the following figure (Hermoso et al., 2010), the same that a low value of the IBMWP (which measures water quality) and QBR (which evaluates the perturbation status of the riparian area).

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The loss of biodiversity and quality of the

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ecosystems supposes a decline of the nature conservation value which will be worse in the future in these areas.

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Responses of the Index of Community Integrity quality classes detailed in the table to different indicators of water quality, physical habitat and biotic perturbations. IBMWP (Alba-Tercedor et al., 2002) measures water quality, QBR Munné et al. (2003) evaluates the perturbation status of the riparian area. The responses to the invasion status (measured as the proportion of invasive species richness and abundance) are also shown (Hermoso et al, 2010).

2.22. How important is it that genetic traits of the organism could be carried to other species, modifying their genetic nature and making their economic, environmental or social effects more serious?

minimal medium There is no evidence of possibility of hybridisation with native species. , howevere there’s evidence of hybridization between species of the same family (Ictaluridae).

I. punctatus (channel catfish) have been known to mate with brown bullhead (Ameiurus nebulosus), yellow bullhead (Ameiurus natalis), and black bullhead (Ameiurus melas), resulting in a variety of hybrid catfish (Florida Museum of Natural History. Online: https://www.flmnh.ufl.edu/fish/discover/species-profiles/ictalurus-punctatus/), 2017)./)

Introgressive hybridization amongbetween A. nebulosus and A. melas may difficult in its differentiation and, furthermore, its control. Hybridization of A. natalis with A. melas and A. nebulosus is rare.

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Hybridization between brown bullhead and black bullhead may occur where the species frequently co-occur. No other hybrids are known within North America. A. nebulosus has been sequenced (CABI, 2015a, 2015b)

. A. natalis has a diploid (2n) chromosome number of 62 and haploid/gametic number of 31. Hybridization with A. melas and A. nebulosus is rare (CABIGodard, 2015b; Mandrak, 2009).)

2.23. How important is social, human health or other harm (not directly included in economic and environmental categories) caused by the organism within its existing geographic range?

minimal medium No effects known (Wiesner et al. 2010).

Black bullheads can cause a painful sting if pectoral spines puncture human flesh. Black bullheads contain small amounts of venom at the ends of spine which can cause pain for up to a week. ("A Boundary Waters Compendium", 2004Rose;, 2006; Etnier and Starnes, 1993).

A painful wound can be inflicted by the sharp spines in the fins of brown bullhead catfish if they are not handled carefully. Toxins released by the fish contribute to the pain of the wound (Global Invasive Species, 2006).2016).

Anglers are in general annoyed by this species with not big interest lately for sport fishing.

2.24. How important is the impact of the organism as food, a host, a symbiont or a vector for other damaging organisms (e.g. diseases)?

moderatemajor

lowmedium

Transmission of pathogens could likely be a risk but, currently, it is not enough documented.

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Ameiurus A.melas host Flavobacterium columnare and Edwardsiolla ictaluri. Diseases of Concern: A. nebulosus are two susceptible species to host Aphanomyces invadans related to the Epizootic ulcerative syndrome (Aphanomyces invadans) - Susceptible Species of Aquatic Animalsand this disease is listed in Schedule IIIthe Part II of the Council directive 2006/88/EC on animal health requirements for aquaculture animals and products thereof, and on the prevention and control of certain diseases in aquatic animals

Ameiurus melas (Black bullhead) hosts Edwardsiella ictaluri in liver and spleen kidney. This parasite is related to Enteric septicaemia of Canada’s Health of Animals Regulations – showscatfish and Edwardsiellosis (Buller, 2014).

Moreover it hosts Flavobacterium columnare related to the Columnaris disease (Buller, 2014).

A.melas is high susceptibility to susceptible to two ranavirus, European catfish virus (ECV infection. Furthermore a significant mortality associated with the typical signs of systemic viral infections was observed in groups challenge with) and Epizootic haematopoietic necrosis virus (EHNV) (Gobbo et al., 2010).

Ranaviruses pose a potential threat to fishs and amphibians. Has also been shown to host Ancyrocephalus pricei in a UK population (Sheath

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et al., 2015).

Epizootic haematopoietic necrosis was observed in 0+ and 1+ old black bullhead reared in polyculture with carp. The disease induced mortality of 6 tons of this species over a one-month period (from mid-August to mid-September), whereas no mortality in carp was recorded at the time nor any sign of the disease in 1+ old carp reared in the same pond (Jeremic and Radosavljevic, 2009).

A. natalis is known to be a host species for creepers (Strophitus undulatus) and are also parasitized by leeches (Hirudinea) (Gray et al., 2001). They are known to host the larval stage (glochidia) of the clam Anodonta grandis [Pyganodon grandis] (Hart and Fuller, 1974).A study of parasites of A. natalis in Texas by Mayberry et al. (2000) found the following: Cestoda: Proteocephalidae, Proteocephalus ambloplitis; Trematoda: Alloglossidium kenti, Cleidodiscus pricei, Phyllodistomum caudatum, Posthodiplostomum minimum, Gyrodactylus; Nemata: Spinectus carolini [Spinitectus carolini], Spinectus microcantus [Spinitectus microcanthus], Spyroxis contorta.

Scott and Crossman (1973) describe the following parasites known from within the species, which have the potential to infect recipient fish communities following A. nebulosus introductions: Protozoa, Trematoda, Cestoda, Nematoda,

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Acanthocephala, leeches, Mollusca, and Crustacea. (http://www.cabi.org/isc/datasheet/94468).In Italy, the introduction of the exotic cestode Corallobothrium parafimbriatum Befus et Freeman, 1973 with A. melas was recorded. The further spreading of the cestode with its fish host to other countries was not recorded. Acanthocephalus anguillae, adopted by black bullhead, is the common parasite of native fishes (about 40 species) in Slovakia (Košuthová et al., 2009).

Ameiurus nebulosus (Brown bullhead)Scott and Crossman (1973) (in Mandrak, 2009) describe the following parasites known from within the species, which have the potential to infect recipient fish communities following A. nebulosus introductions: Protozoa, trematoda, cestoda, nematoda, acanthocephala, leeches, mollusca and crustacean.

A.nebulosus hosts Carnobacterium (piscicola) maltaromaticum in kidney. It may be carrier. (Buller, 2014).

It hosts Edwardsiella ictaluri related to an infection in the brain, with systemic dissemination and localization in the visceral organs and musculature and cutaneous ulcers; to Enteric septicaemia of catfish (ESC) and Edwardsiellosis (Buller, 2014).

Moreover it hosts Edwardsiella tarda related to septicaemia, focal suppurative or granulomatous

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lesions and cutaneous ulcerations; and to Edwardsiellosis. It’s an ppportunistic infection (Buller, 2014).

Ameiurus natalis (Yellow bullhead) is known to be a host species for creepers (Strophitus undulatus) and are also parasitized by leeches (Hirudinea). They are known to host the larval stage (glochidia) of the clam Anodonta grandis (Pyganodon grandis). A study of parasites of A. natalis in Texas found the following: Cestoda: Proteocephalidae, Proteocephalus ambloplitis; Trematoda: Alloglossidium kenti, Cleidodiscus pricei, Phyllodistomum caudatum, Posthodiplostomum minimum, Gyrodactylus; Nemata: Spinectus carolini (Spinitectus carolini), Spinectus microcantus (Spinitectus microcanthus) and Spyroxis contorta (Godard, 2015).

Ameiurus catus (White catfish) hosts Edwardsiella ictaluri related to Enteric septicaemia of catfish (ESC).

2.25. How important might other impacts not already covered by previous questions be resulting from introduction of the organism? (specify in the comment box)

NA

2.26. How important are the expected impacts of the organism despite any natural control by other organisms, such as predators, parasites or pathogens that may already be present in Europe?

major medium It is not well know how predators, parasites or pathogens could affect thethese species. At least in Spain the only possible fish predators will be also exotic. Native species are usually smaller (70% of

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then endemic) and with small mouths which make them bad competitors.

Although A. nebulosus are predated upon by larger fishes, the likelihood of long-distance dispersal resulting from this vector is low. Most piscivorous fishes are unable to utilize A. nebulosus for food due to their sharp, strong dorsal and pectoral spines that may lock into an erect position when predated upon (CABI, 2015b).

Ameiurus melas (Black bullhead) have large sharp spines on both their dorsal and pectoral fins; when attacked they straighten them making them difficult to swallow and as such very few predators are able to consume them. This species also produces a mild poison that runs down the spines and into the wound. These spines combined with the species' nocturnal feeding regime make black bullheads an uncommon prey item for other fish species. Smallmouth bass (Micropterus dolomieu), largemouth bass (Micropterus salmoides), herons as well as some turtle species occasionally consume the young and small adults, with their main predator being humans. (CABI, 2015a) (Godard, 2015b).

Ameiurus nebulosus (Brown bullhead)Although A. nebulosus are predated upon by larger fishes, the likelihood of long-distance dispersal resulting from this vector is low. Most piscivorous fishes are unable to utilize A. nebulosus for food

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due to their sharp, strong dorsal and pectoral spines that may lock into an erect position when predated upon (.Mandrak, 2009).

The adult of Ameiurus nebulosus by virtue of its strong pectoral and dorsal spines, the adult A. nebulosus is well protected from predation by all but the largest fish predators in their native range in Canada. Although present in juveniles, the spines are less robust making juveniles more susceptible to predation by fishes with a wider range in size. Within its native range, predators include members of the pike family (Esox spp.) and pike perches (Sander spp.). Where introduced on the Gulf Islands of British Columbia in Canada, there are no other piscivorous fishes present and, hence, no native predators to introduced A. nebulosus (CABI, 2015bMandrak, 2009).

Ameiurus natalis (Yellow bullhead)Several natural enemies of A. natalis have been reported in its native range; however, by virtue of their strong pectoral and dorsal spines, adults are well protected from predation by all but the largest fish predators Members of the pike family (Esox species), walleye (Sander vitreus), large wading birds and some turtles may feed on adults. (CABI, 2009; Godard, 2015a).

Juvenile spines are less robust making them more susceptible to predation by fishes with a wider range in size. Within its native range, predators of

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juveniles include Micropterus salmoides, M. dolomieu, Sander canadensis, species of Ambloplites and Pomoxis including Pomoxis nigromaculatus and other catfish as well as aquatic invertebrates, leeches and crayfish. The eggs and small fry are predated by Lepomis macrochirus and other species of Lepomis (CABI, 2009Godard, 2015a).

2.27. Indicate any parts of Europe where economic, environmental and social impacts are particularly likely to occur (provide as much detail as possible).

[In all rivers, reservoirs, dams, lakes, lagoons and ponds]

medium Negative impacts could occur in all the distribution area where it is established.

Particularly National Parks, areas of high value for the conservation of nature are more susceptible to suffer high economic, environmental and social negative impacts.

In Spain, the National Park Tablas de Daimiel (http://www.castillalamancha.es/sites/default/files/documentos/paginas/archivos/doc_1_es0000013_0.pdf). And the Doñana Natural Area are two important conservation areas that suffers because of the reproduction of Ameiurus melas in their waters

In France the species is included in the list of Fish species recorded on the Natura 2000 site of the Lower Valley Doubs -– Doubs and Clauge.

Ameiurus melasEverywhere there is potential for the black

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bullhead to cause aenvironmental, economic and negative social impact as it can be a 'nuisance' species taking lines/bait intended for other species, because of this (anglers not targeting this species might move on to black bullhead free waters (CABI, 2015aGodard, 2015b).

Ameiurus nebulosus populations may hinder local native sport fisheries by out-competing target fishes, resulting in reduced angling opportunities and their social impacts. Alternatively, introductions may be encouraged locally if A. nebulosus are favoured for sport. Introduction into previously fishless waters may provide new or valued angling opportunities. Current estimates of social impacts resulting from introductions have not been documented (CABI, 2015b).Mandrak, 2009).

As the water temperature is the most limiting factor we can assume that possibly the more affected regions following the establishement of any of Ameiurus species would be:Macaronesian biogeografical regionMediterranean biogeografical region

(In Q.4 there is more information given about the biogeographics areas where Ameiurus species are already established or they could establish.

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RISK SUMMARIES

RESPONSE CONFIDENCE COMMENTSummarise Entry Moderately high At least Four of the total of seven species of

Ameiurus genus are already present have been recorded in Europe, (2421 of the total of 28 European countries have recorded at least one Ameiurus spspp). In the meantime the interest of this species for fishing has been reduced lately, and some countries have forbidden new entries of A. melas and A. neboulosus (France, Poland, etc.).The entry pathways for the species that have benn -recorded in Europe were:-ornamental fish;-unintentional introductions through stocks with contaminated fish;-intentional stocking for sport fishing and food.As analised in the Section Entry Pathways, none of those entry pathways can be descarted nowadays.New entries from North America are not very likely but trade could still be done between countries and release to nature is possible formo pet owners and anglers.

So it is necessary to prevent entry through banning of these species from trade and educating the public about their impact

Summarise Establishment very likely high At least one Ameiurus sp. spp. (A. melas or A. nebulosus) is established in France, (only A. melas), Germany, Austria, Italy, Portugal, Spain, the Netherlands, Belgium, Czech Republic,

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Croatia, Romania, Finland, Hungary, Slovakia, Slovenia, Bulgaria, Greece, Croatia, Ireland, Romania, Poland, Sweden, (only A. melas), Denmark, Estonia (only A. nebulosus) and the United Kingdom. A. nebulosus has been cited as established in many countries, although it seems to be A. melas in most cases. A. melas and A. nebulosus would probably adapt easily to the climatic conditions in Malta and Cyprus and possible inwith climate changes in Estonia, Lithuania and Latvia.

This demersal species inhabits low-flowing habitats (limnophilic) with soft substrata in all riverine and lacustrine environments, including artificial ones such as ponds and reservoirs.

The great growth and life-history plasticity of black bullhead affords the species great potential to invade and establish viable populations in new areas.

Summarise Spread moderately medium In Europe most of the hydrological systems are permanently or temporarily connected. That is why any introduction of an alien taxon into any of the regions, countries, or drainage areas will result in its gradual spontaneous dispersal into further regions and drainage areas, provided that the introduced taxon can find suitable environmental conditions. In most cases this dispersal is intentionally or unintentionally aided by man. Recent persuasive examples include the expansion of C. gibelio, P. parva, P. glenii, or A. melas,

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indicating that there may arise grave problems concerning alien species which will spread without any intentional introduction. Even the unintentional introduction of A. melas with carp stocks into the Czech Republic is evidence that it is illusory to believe in abiding with principles and measures preventing unintentional import or spreading of alien species. It should be realised that in the conditions of central Europe, any introduction of alien species has international dimensions and ceases to be the matter of any individual country (Lusk et al, 2010)

The spread by natural means could be more important that by human assistance for the species already present in Europe The expansion depends on ecological conditions of river basins in which it is introduced, but if it finds suitable conditions, it can be easy for these successful invaders to spread. A reduction in native species richness – for example, caused by hydromorphological changes or anthropogenic influences – may affect the resilience of communities to invasions (Dunstan and Johnson, 2006), or eutrophication may dramatically alter the food-web structure in favour of non-native species.

This means that Ameiurus spp. could spread easily to other ecosystems.

Flexible life-history traits and wide environmental tolerances facilitate Ameiurus spp. establishment

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and dispersal.In conclusion, Ameiurus spp. could spread easily to other ecosystems.

Summarise Impact major medium Ameiurus spp. is generalist, foraging on the most abundant and available prey. The impact is because of the competition, due to the coincidences with the preys used by some native species, direct predation of native species and habitat degradation.

Impacts in water quality, such as increased turbidity, have also been demonstrated.

A.melas, A. nebulosus, A. natalis and A. catus are species tolerant of pollutants, low dissolved oxygen (3.0 mg L-1), and elevated water temperatures (up to 35 ºC) the brown black bullhead also has a specialized, nest-guarding, reproductive strategy. Many of introduced fishes in Europe are nest-guarders, which suggests that the bullheads have the potential to be highly invasive and exert impacts to ecosystem function through increased turbidity (Copp et al., 2016; Mandrak, 2009; Godart, 2015)

See Impact Section for examples of impact on native species worldwide.

Conclusion of the risk assessment major medium Once established in a river basin, the bullheads´ eradication is generally impossible. Prohibiting trade in the absence of cost-efficient management methods would probably not efficiently tackle the

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problem for established Ameiurus species, but would diminish the risk for other Ameiurus species to entry and establish, as well as new introductions in water basins. Anyway we recognize that more information is necessary to understand whether active pathways are relevant for the actual and future spreading compared to natural spread and whether management of active pathways would thus efficiently reduce the impacts. In the mean time a precautionary approach is suitable in order to prevent further invasions and their negative effects.

The release and translocation of specimens by fishermen and pet-owners and the easy adaptability to the natural conditions in the lakes and rivers from Europe, makes possible its continuous expansion transforming aquatic ecosystems and causing the disappearance of native species, mainly fish.

Aquatic habitats are one of the habitats more threatened by invasive alien species (IAS). At present IAS are one of the most important direct drivers of biodiversity loss throughout the world and constitute the greatest threat to fragile ecosystems such as small isolated water bodies.

ADDITIONAL QUESTIONS - CLIMATE CHANGE3.1. What aspects of climate change, if any, are most likely to affect the risk assessment for this organism?

[Temperature; rain]

medium The effects of climate change in the progressive warming of water, even in temporary drying up of rivers, during which this species is able to stay buried in the mud, would favour its population

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increase, which would be a major impact on native species. Aquatic environments are particularly affected by climate change.

Species composition, diversity, global abundance and size structure of fish communities exhibited important trends related to water warming in large rivers (http://www.firf.fr/team/martin/1fichiers/1pdf/DaufresneGCB2007.pdf).Cucherousset et al. (2007) studied fish emigration patterns from four temporary wetlands exposed to drought from May to August 2004 in the Brière Marsh (France). Emigration timing was highly correlated with published physiological tolerance levels for these species, demonstrating a tight linkage between water quality and emigration patterns. Two non-native species (A. melas and G. holbrooki) showed the latest emigration from the temporary habitats, reflecting a high level of tolerance to drought conditions that may contribute to their success as wetland invaders (Cucherousset et al, 2007).

The greater hydrological variability predicted to accompany the warmer climatic conditions is expected to increase fish dispersal, so wider establishment of non-native fishes is likely to enhance the risks of adverse consequences for native species and ecosystems (Coop et al, 2004). However, existing evidence for adverse impacts remains equivocal or lacking for many nonnative

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fishes.3.2. What is the likely timeframe for such changes? 4020 years low Aquatic environments are particularly affected by

climate change.For the next two decades, a warming of about 0.2°C per decade is projected for a range of different emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected (IPCC Fourth Assessment Report: Climate Change 2007).

Some climate change signal is found in sea level pressure in the winter season with lower pressure in the Northeast, but the signal is not very robust. This is however consistent with the temperature and precipitation changes and suggests expansion of the subtropical dry zone into Southern Europe and an enhanced hydrological cycle in Northern Europe and Scandinavia (Vautard et al, 2014).

3.3. What aspects of the risk assessment are most likely to change as a result of climate change?

[Increase suitability of the habitat for the species]

medium The water temperature could also explain the change in habitat use and searching behaviour by bullheads. In the wild, bullheads and crappies would compensate for the increased water temperature by finding areas that contain cool water temperatures, allowing their body temperature to cool as a result. (Walberg, 2011). This could result in a natural spread in colder waters such as Latvia´s and Lithuania´s ones, where Ameiurus spp seem not to be recorded yet.

Additionally, where A. melas is present in more temperate climates (UK for example), increased

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water temperatures as a result of climate change could extend the period for successful spawning and increase foraging efficacy (Environment Agency- UK, unpublished data).

ADDITIONAL QUESTIONS - RESEARCH4.1. If there is any research that would significantly strengthen confidence in the risk assessment please summarise this here.

[The impact to native fauna should be further investigated]

medium Confidence in the risk assessment is high for establishment, spread and damage in aquatic ecosystems. Data on the possible impacts on native species, principally on endemic fishes, are needed. Further studies are required to assess these impacts. It would be very important to increase the management actions to protect them.

Research into the efficacy of bio-control and bio-manipulation of A. melas populations should be investigated (cf. Davies and Britton, 2015), to provide additional control measures to those already available (See Comment 1.21).

Further investigation is needed to assess Ameiurus population trends and impacts, such as decline of reservoir water quality and food web structure alteration.

Further cost data are also needed.

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