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Ocean & Coastal Management 86 (2013) 53e60
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Ocean & Coastal Management
journal homepage: www.elsevier .com/locate/ocecoaman
Meeting the giants: The need for local ecological knowledge (LEK) as atool for the participative management of manatees on Marajó Island,Brazilian Amazonian coast
M.E.M. Sousa a,b,*, B.M.L. Martins b, M.E.B. Fernandes a
a Laboratório de Ecologia de Manguezal e LAMA, Instituto de Estudos Costeiros, Universidade Federal do Pará, Campus de Bragança,68600-000 Bragança, PA, BrazilbGrupo de Estudos de Mamíferos Aquáticos da Amazônia e GEMAM, Coordenação de Zoologia, Museu Paraense Emílio Goeldi, Campus de Pesquisa,66.077-830 Belém, Pará, Brazil
a r t i c l e i n f o
Article history:Available online 10 November 2013
* Corresponding author. Laboratório de Ecologia dede Estudos Costeiros, Universidade Federal do Pará, C000 Bragança, PA, Brazil.
E-mail addresses: [email protected], ma(M.E.M. Sousa).
0964-5691/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.ocecoaman.2013.08.016
r e s u m o
O Conhecimento Ecológico Local (CEL) tem sido bastante utilizado como uma fonte de informaçãoconfiável para o desenvolvimento de pesquisas sobre a ecologia de peixes-boi. Com base nesta abor-dagem, o presente estudo avaliou o nível de conhecimento sobre o peixe-boi dos pescadores locais dacosta leste da Ilha de Marajó, no litoral da Amazônia brasileira, que apresenta uma zona de simpatria ehibridização entre as especies de peixes-boi marinho e amazônico. A maioria dos entrevistados (70%)tinha um alto nível de conhecimento em relação a esses mamíferos, e forneceram informações confiáveispara o mapeamento da ocorrência de peixes-boi na área de estudo, incluindo a identificação dos hábitatse áreas mais adequadas para sua ocorrência (tais como: hábitos alimentares, áreas preferenciais e reg-istros de avistamentos). Os desafios enfrentados pela pesca, assim como o entendimento de demaisquestões relativas aos desafios da região amazônica mostra a relevância dos dados apresentados nessapesquisa. E este estudo reforça o valor de tais informações repassadas pelos pescadores, e de como pode-se associa-las ao saber científico como uma ferramenta eficaz para a gestão participativa de peixes-boi aolongo da costa amazônica brasileira.
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a b s t r a c t
Local ecological knowledge (LEK) has been widely used as a source of reliable information for thedevelopment of research on the ecology of manatees. Based on this approach, the present study eval-uated the level of knowledge related to manatees among the local fishermen on the east coast of MarajóIsland on the Brazilian Amazonian coast, which represents a zone of sympatry and hybridization be-tween marine and Amazon species of manatees. Most of the interviewees (70%) displayed a high level ofknowledge with regard to these mammals, and provided reliable information for mapping of theoccurrence of the manatees within the study area, including identifying the habitats and areas that aremost appropriate for their occurrence (based on their eating habits, preferred areas and records ofsightings). The challenges faced by fishers as well as knowledge of other issues related to the challengespresent in the Amazon region demonstrate the relevance of the data presented in this study. Further-more, our findings reinforce the value of such information provided by fishermen, and demonstrate howit can be associated with scientific knowledge as an effective tool for the participatory management ofmanatees along the Brazilian Amazonian coast.
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Manguezal e LAMA, Institutoampus de Bragança, 68600-
All rights reserved.
1. Introduction
In some countries, social ecology has become increasinglydependent on the ethnosciences, particularly on ethnobiology, as a
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e6054
tool for the conservation of natural resources (Diegues, 1999).Peterson et al. (2008) define ethnobiology as the study of theknowledge and concepts presented by a society with regard to thelocal biota. Begossi et al. (2002) argue that an ethnobiologicalapproach may provide important insights into the relationshipbetween local populations and their natural environment, andcontribute to the development of effective conservation measuresas well as to the scientific knowledge of organisms and theirecological characteristics. According to the ethnoscientist, man-agement of the environment may be accomplished through thesetraditional populations. In this context, the present study adoptedDiegues’s (2004) definition of local communities, which are char-acterized by their dependence on natural resources, and a profoundknowledge of the environment in which they live.
Information provided by local fishermen and other residentsmay contribute to the monitoring of coastal environments byprovide important technical and biological data (Grant and Berkes,2007). Oliveira et al. (2001) confirmed that obtaining informationfrom local fishermen is an important component of any researchinto the management of cetacean populations, given the effects offishery activities on these animals.
In Brazil, a number of studies have applied the documentation oflocal ecological knowledge as a strategy for the collection of data onmanatees (Trichechus spp.). In the 1980s, Albuquerque andMarcovaldi (1982) surveyed the remaining populations of mana-tees on the Brazilian coast, between Amapá and Rio de Janeiro,based on the examination of letters, questionnaires, and fieldstudies and found that the Antillean manatee, Trichechus manatusmanatus, had already disappeared from a long stretch of the Bra-zilian coast, ranging from the state of Espírito Santo to Bahia,extending for more than 2 000 km. Through interviews withhunters and collection of skeletal remains, Domning (1981) docu-mented the distribution of manatees between Amapá and Mar-anhão and identified possible areas of sympatry between the twolocal species: coastal T. manatus and riverine Trichechus inunguis.This study established the Amazon estuary as a zone of sympatrybetween these two species. In northeastern Brazil, local ecologicalknowledge is a fundamental tool for the surveying and monitoringof populations of T. manatus (Alves, 2007; Costa, 2006; Lima, 1997;Paludo, 1998).
The manatee is an integral part of local cultures and traditionsin the Amazon region, although these animals have also beenhunted extensively by indigenous and traditional riverside com-munities for their meat and medicinal properties. The manateepopulations of the New World were estimated to be in the tens ofthousands when the Europeans first arrived, but the succulentmeat of the animals, which was easy to preserve, and thenumerous uses for their blubber and leather led to harvesting ofmanatees on an industrial scale (Caldwell and Caldwell, 1985).Some hunting of both species is still thought to occur within theBrazilian Amazon region, with predictably negative effects on theirremaining populations (IBMA, 2001). A range of anthropogenicimpacts also contribute indirectly to the deaths of manatees inthe wild.
Centuries of intensive hunting have led to dwindling of thepopulations of manatees along the Marajó coastline and inlandwaters. However, as the numbers of hunters and the use of tradi-tional hunting techniques have diminished, manatees may berecovering slowly in these areas. Thus, we decided to evaluate theecological knowledge of local fishermen on Marajó Island, which issituated in the state of Pará along the Brazilian Amazonian coast-line. The aim of this study was to map the areas of occurrence ofthese mammals in the Amazon estuary, which is part of the zoneof sympatry and hybridization of T. manatus and T. inunguis(Luna, 2012).
In addition, our findings will help to identify areas used bycoastal manatees for the future reintroduction of three manateecalves recently found on the coast of Pará.
2. Materials and methods
2.1. Study area
The municipalities of Salvaterra and Soure are located on theeast coast of Marajó Island (0e2� S, 48e51� W), in the northernextreme of the Brazilian state of Pará. This island is limited to thenorth by Amapá and the Atlantic Ocean, to the south by the ParáRiver, to the east by Marajó Bay, and to the west by Amapá (Lima,2005). The study area is 86 km due north of the state capital,Belém (Fig. 1), but it can only be reached by air or water-bornetransport (França, 2003). The entire study area is located withinthe Marajó Archipelago Environmental Protection Area (APAArquipélago doMarajó), and the municipality of Soure is within theSoure Marine Extractivist Reserve (RESEX Soure).
2.2. Data collection and analysis
The interviews were based on semi-structured questionnaires,which focused on three principal topics: (i) personal information:name, nickname, age, length of fishing career, profession, and homeaddress; (ii) fishing practices: fishing techniques, equipment used,and types of fish exploited; and (iii) manatees: occurrence, habitatpreferences, morphology, and uses (see Appendix). The interviewswere conducted during 11 excursions into the study area, with amean duration of 3 days per month. The manatee is endangeredwith extinction and legally protected, which means that fishersgenerally feel intimidated when questioned about their relation-ship with these animals. To reduce any possible bias caused by thissituation, the questions were presented in the above order, i.e.,topic (i) first, followed by topic (ii), and then (iii).
The research focused on the local fisheries, and all of theinterviewed subjects were fishermen. Sampling was based on thesnowball approach (Bernard, 1995), where one or more potentialinformants were identified, and then asked to indicate other localfishermanwhowould agree to be interviewed. The interviews wereconducted at either the residence or the workplace of the inter-viewee, depending on their availability. Whenever possible, thefisherman was interviewed alone, to minimize interference fromother members of the community. The datawere recorded in a fieldnote book and subsequently entered into a BROffice-Base database,where each interview was given a catalog number.
To determine the fishermen's level of familiarity with themanatee, the interviewees were evaluated with regard to theirknowledge of the animal’s (i) morphological characteristics, (ii)feeding behavior, and (iii) habitat preferences. Based on this eval-uation, the subjects’ knowledge was classified as (i) EXCELLENT e
knowledge of all three parameters; (ii) GOOD e knowledge of twoparameters; c) REGULAR e knowledge of only one parameter; or(iv) NULL e no knowledge reported.
In the analysis of local ecological knowledge, the results ofquestions with only one possible answer were presented as per-centages, whereas thosewithmore than one potential answer werepresented as absolute frequencies. Negative responses, such as “Idon’t know”, “I haven’t got an answer”, and “I can’t tell you”, werecomputed separately. Finally, all of the information provided by theinterviewees was checked against the scientific databases availablein the literature.
Potential differences in the knowledge and experience of theresidents of the municipalities of Salvaterra and Soure weredetermined using Chi-squared (c2) tests. The tested variables
Fig. 1. Map showing the study area on the eastern coast of Marajó Island in the Brazilian state of Pará.
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e60 55
included sightings (live or dead animals and infants), feedingbehavior (carnivory or herbivory) and habitat preferences (salinity,tides, availability of feeding resources, and seasons).
2.3. Participative management
For this type of research, it is believed that cooperation betweenresearchers and fishermen is essential for future actions regardingthe management of these species to succeed. Such cooperationrequires an understanding of the conflicts faced by the fisheries andthe bond of trust established between researcher and fisherman. Inthis study, we developed lectures and participatory meetings withlocal fishermen, and the intention is to return and discuss the re-sults obtained through the interviews, especially related to theoccurrence of the species, with the fishermen.
Table 1Knowledge of the characteristics of the manatee presented by the fishermeninterviewed on the east coast of Marajó Island, in the Brazilian state of Pará.
Category Information provided on: IntervieweesN (%)
Excellent Anatomy, feeding behavior, and habitatpreferences
67 (70)
Anatomy and feeding behavior 12 (13)Good Feeding behavior, and habitat preferences 1 (1)
Anatomy and habitat preferences 5 (5)Habitat preferences 2 (2)
Regular Anatomy 1 (1)Feeding behavior 2 (2)
Null No information 6 (6)
3. Results
3.1. The fishermen of the east coast of Marajó Island
A total of 96 fishermen, from four communities on the east coastof Marajó Island were interviewed. Two-thirds of (67%, n ¼ 64)were residents of the village of Joanes, in the municipality of Sal-vaterra; 20% (n ¼ 19) were from the town of Soure; 11% (n ¼ 11)were from the village of Caju-una (municipality of Soure); and only2% (n ¼ 2) were from Jubim community (Salvaterra). The in-terviewees were not selected by gender, although only three werewomen, two from Joanes, and one from Soure.
The ages of the interviewees ranged from 16 to 80 years, with amean of 45 years. Most (79%, n ¼ 75) of the participants hadpracticed fishing for more than 20 years, while the other 21%(n ¼ 21) had fished for less than 20 years. All of the fishermeninterviewed are registered in the local Fisher Colony, although thisentity is involved only in fishery-related activities, such as thepayment of insurance and pensions.
3.2. Evaluation of the fishers’ knowledge about manatee
Overall, the majority of the interviewees (70%, n ¼ 67) exhibitedan excellent level of knowledge of the manatees (Table 1), pre-senting reliable information on themorphological characteristics ofthe animals as well as their habitat preferences and feedingbehavior. At the opposite extreme, only 6% (n ¼ 6) of the in-terviewees were classified in the null category; i.e., they displayedno working knowledge of the animal whatsoever. Some in-terviewees reported that manatees will sometimes become trap-ped in fishing weirs but that they do not interfere with the captureof the fish and are released immediately when found.
3.3. Local ecological knowledge (LEK)
3.3.1. General characteristicsWhen the fisherman were asked about the general morpho-
logical characteristics of the manatees, they were able to describethe animals clearly (Table 2). This reflects the fact that most of theinterviewees had had some contact with manatees, which rein-forced the reliability of their other answers.
Table 2Comparison of local ecological knowledge on the general characteristics of themanatees provided by the fishermen of the east coast of Marajó Islandwith established scientificknowledge on the animals. N ¼ number of times the feature was cited (percentage).
Characteristic Local ecological knowledge Scientific knowledge Feature N (%)
Generalmorphology
"They have little appendages, like arms, and the tail is like afan, the body is like a barrel, they have really big lips, and theteats are in the armpits." (Interview 51)
Sirenian bodies are fusiform, with no dorsal fin or pelviclimbs (Reeves et al., 2002).
e e
Sexualdimorphism
"(...) she had teats and they were full of milk (...) more or lesslike in humans, near the flippers (...) (Interview 71)
The visible differences between males and females are: thegenital opening which is located anteriorly to the anus inthe females and posteriorly to the navel in themales, and hepresence of a teat under the pectoral fins of the females(Hartman, 1979)
e e
Tail "Smooth fins, the tail looks like a big racquet." (Interview86)
The tail fin is large and rounded, like a paddle, and is theprincipal means of propulsion (Hartman, 1979)
e e
Size "(...) it is very big, 4, 5 m. Not that long, but portly. It’s got lips,just like on a bull’s face. Bull’s skin" (Interview 74)
An adult Antillean manatee may reach 4.5 m in length andweigh 600 Kg (Hartman, 1979)
e e
‘Gray’ 3 (4)Color "it is black, it looks like a bull, it is beautiful, it has got a
nose" (Interview 7)The skin is darker, almost black, in the Amazonian manatee(T. inunguis), which also normally have whitish ventralmarkings (Husar, 1978).
‘Dark’ 9 (11)‘Brown’ 1 (1)‘Reddish’ 1 (1)‘Black’ 65 (82)
Behavior "(...) they don’t jump out of the water because they are too big(...)" (Interview 77)
Manatees normally swim close to the surface of the water,with the top of their heads and eyes out of the water(Hartman, 1979)
‘Floating’ 14 (27)
"The head or the back sticks out of the water." (Interview 83) ‘Eating’ 27 (52)‘Moving’ 1 (2)
"They raise their heads, as though they are breathing."(Interview 92)
‘Swimming’ 3 (6)
"(...) they don’t stop eating, night and day." (Interview 34) ‘On the bottom’ 1 (2)‘Breathing’ 6 (12)
"(...) sometimes there is a male and a female, but other times,they are alone." (Interview 90)
‘Solitary’ 25 (42)
Group size "Usually the mother and infant are together." (Interview 92) Manatees are solitary, but mothers are accompanied bytheir infants (Alves, 2007).
‘Two’ 25 (42)"(...) there are normally only a few of them, it’s a rare fish."(Interview 60)
‘Three’ 6 (10)
Reproduction "(...) when the female is on heat, we see more of them."(Interview 56)
Groups usually form during the mating period (Marmontelet. al., 1992)
‘More thanthree manatee’
4 (7)
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e6056
A total of 80 positive answers were given with regard to thecolor of the animal, which were distributed in five categories, themost frequent of which was “black” (82%, n ¼ 65), followed by“dark”, at 11% (n ¼ 9). “Brown” and “reddish” were the colors thatwere least commonly mentioned (Table 2).
When asked what the manatees were doing when they weresighted (52 positive answers), most of the interviewees (52%,n ¼ 27) cited “feeding”, followed by “floating” (Table 2). “Swim-ming”, “moving”, and “on the bottom” were the least-cited cate-gories. Some of the interviewees reported observing groups ofmanatees consisting of three or more individuals (Table 2),although the vast majority reported that the animals were solitary(42%, n ¼ 25) or found in pairs (42%), either consisting of mothersand their infants or two adults.
A total of 101 positive answers were given with regard to thetype of food consumed by the manatees, with 16 different itemsbeing identified. Most of the interviewees (91%, n ¼ 92) correctlyidentified the manatees as herbivores, with the majority (65%,n ¼ 66) citing sea grass as the food source, followed by “patorá”, atype of aquatic forage (11%, n ¼ 11). In three cases, however, theinterviewees cited “shrimp”, “fish”, and “shellfish”, constituting 9%(n ¼ 9) of the answers. These respondents understood that themanatees may sometimes eat animal foods.
3.3.2. OccurrenceWhen asked whether they had ever seen a manatee, 81% of the
fishermen (n¼ 78) confirmed that they had seen the animal withinthe study area. Five of the 18 subjects who had never seen theanimal personally had heard reports of its occurrence in the region.Most of the fishermen (57%, n ¼ 55) had seen manatees more thanonce, and 24% (n ¼ 23) had seen them once. There was a significantdifference between the municipalities of Soure and Salvaterra(c2 ¼ 693.27; d.f. ¼ 2; p < 0.001) with regard to reports of the
occurrence of Trichechus. A number of other individuals, includingtourists, university professors, and local residents, also reported theoccurrence of manatees in the area.
A total of 22 different locations of manatee occurrences wereidentified within the study area (Table 3, Fig. 2). In Salvaterra, Portowas the locality cited most frequently, followed by Joanes. In Soure,the reports were concentrated in Garrote and Caju-una village.There are no industrial installations or other economic activities inthe study area that might cause environmental degradation, so themanatees’ habitat is well preserved.
Infant manatees appear to be rare, and only 25% (n ¼ 20) of thefishermen confirmed having observed them in the wild. There wasno difference (c2 ¼ 32.33; d.f. ¼ 4; p > 0.05) in the number of re-ports of infants coming from Soure and Salvaterra. However, thesefew reports were consistent with regard to the occurrence ofparental care. The respondents provided 45 positive answers,which referred, in most cases (84%, n ¼ 38), to the consumption ofmilk (“suckling”), with the other 16% of cases (n ¼ 7) referring toherbivorous behavior (“eating plants”). Some of the subjects simplydescribed the feeding behavior of the infants by referring to thezoological classification of the animals as “mammals”.
3.3.3. Environmental parametersWith regard to the habitat preferences of the manatees, most of
the 55 positive answers (64%, n ¼ 35) referred to a preference forfreshwater environments, whereas 20% claimed that the animalsdisplayed no clear preference for either salt- or freshwater(Table 4). Again, there was no difference between the municipal-ities in the distribution of answers (c2 ¼ 0.36; d.f. ¼ 2; p > 0.05).
The fishers indicated that the presence of the manatees in agiven area was influenced primarily by their preference for rela-tively “calm” locations. The word “calm”was used to describe areasthat are sheltered from both natural hydrodynamics and the transit
Table 3Knowledge of local fishermen on the spatial distribution of manatees within thestudy area on the east coast of Marajó Island.
Selected quotes from the interviews
"They reproduce up in the Amazon." (Interview 51)"we always see them here (Farol-Joanes), this is where they pass through", "look
for an isolated place, that’s where they spend most of the winter" (Interview 57)"(...) there’s a beach somewhere yonder where they go (Siriuaiá)." (Interview 59)"they move around a lot, coming in on the freshwater, this is where they pass
through, coming from Machado on their way to the Amazon" (Interview 61)"When the tide rises, they come in (Joanes), and when it lowers, they go that way
(Pacoval)." (Interview 82)
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e60 57
of vessels and people. In addition to fishing, tourism is the principaleconomic activity in coastal areas, although the influx of tourists ishighly seasonal, and the principal areas visited e Pesqueiro Beachin Soure and Grande Beach in Salvaterra e do not appear to play animportant role in the local distribution of the manatees.
Of the 22 positive answers related to the influence of the tides,most (82%, n ¼ 18) cited high tide as the situation in which theanimals are most likely to be encountered, although ebb and low
Fig. 2. Map of the locations at which manatees were repor
tides were also mentioned specifically. In addition to tidal condi-tions, migration routes were indicated, specifically referencing ac-cess to the animals’ feeding grounds (21 positive answers).
In relation to the seasons, the rainy period was cited almostuniversally (93%, or 28 of 30 positive answers), while the dry seasonwas mentioned by only two subjects (7%), despite the fact that thewater tends to be more transparent during this period. No positiveanswers were provided with regard to the possible influence of themoon on the behavior of the animals.
3.3.4. Where to carry out reintroductions?Through cross-referencing the information on the environ-
mental preferences and the occurrences of the manatees, it waspossible to identify the most suitable area for the implementationof a semi-captive area to allow animals rehabilitated in captivity toacclimate to free living. Among the reports of the occurrence of themanatees, the municipality of Salvaterra received 67% (n ¼ 60) andSoure 24% (n ¼ 22). Regarding environmental preferences, we onlyused information from fishermen classified as excellent, good, orregular, which accounted for 78% (n ¼ 75) of the fishermen, whoindicated (i) “calm regions”, (ii) access to feeding areas, and (iii) low
ted to occur on the east coast of Marajó Island, Brazil.
Table 4Comparison of local ecological knowledge of the environmental parameters that determine the distribution of the manatees provided by the fishermen of the east coast ofMarajó Island with established scientific knowledge on the animals. N ¼ number of times the feature was cited (percentage).
Parameter Local ecological knowledge Scientific knowledge Feature N (%)
Availability offreshwater
"They like to stay close to the creeks." (Interview 87) The marine T. manatus depends on sources of freshwater,such as springs and river mouths (Lima et al., 1992).
‘Open water’ 3 (5)‘Freshwater’ 35 (64)
"They like freshwater, they go into the creeks." (Interview54)
Factors that influence the distribution of manatees:availability of aquatic plants, access to channels of at least2 m in depth, and sources of freshwater (Hartman, 1979).
‘Saltwater’ 6 (11)‘No preference’ 11 (20)
Natural hydrodynamicsand anthropogenicdisturbance
"From the creek (Limão) to there and then to anotherplace, they like to remain there because it is calmer."(Interview 56)
In Ceará, the occurrence of T. manatus is favored by calmwater, weak currents, and a reduced surf zone (Alves, 2007).
e e
"(...) they can be found in Siriuaiá (between Tabocas andPilão) because it is calmer, even the tide is calmer in thisbackwater." (Interview 56)
e e
"They prefer calm water." (Interview 25) Trichechus manatus tends to avoid water with fast currentsor strong waves, and prefers ample bodies of water, such asestuaries and lagoons or inlets protected by reefs (O’Sheaand Kochman, 1990).
e e
Tide "(...) they come in on the flood tide, and go out on the ebb(...)" (Interview 9)
Access to beds of aquatic vegetation and algae maydetermine the distribution of T. manatus on a local scale(Costa, 2006).
‘High’ 18 (82)
"They work in this grass bed (...) when the tide is high, theycome here to eat grass." (Interview 95)
The manatees are more active when the tide is turning orflooding, which facilitates observation in their naturalenvironment (Lima, 1997).
‘Low’ 3 (14)
"They come right to the edge here when the tide is high."(Interview 75)
‘Ebb’ 1 (5)
Availability of food "They like places near the river where there is aquaticvegetation." (Interview 10)
The mean frequency of manatees in areas where food plantswere available (macroalgae, marine phanerogams,mangrove, and other) was significantly different(p < 0.0169) in comparison with areas where no resourceswere available (Lima, 1997).
e e
"there are a lot at Fazenda Pilão because there is still a lotof grass there, a really big bed " (Interview 2)
e e
"...they are rare, and very difficult to see, only on theranches where there is a lot of grass..." (Interview 5)
e e
Moon "They appear most in the freshwater, but the moon doesn’tmatter (...) manatees come in on the high tide to feed."(Interview 14)
In Ceará, no significant difference was found in the numberof sightings of manatees during different moon phases(Alves, 2007).
e e
"They are here in the summer*, but they are a bit lost."(Interview 51)
Season "The manatees are here in the summer and the winter, butmostly during the winter, especially during the high waterin March" (Interview 7)
The riverside dwellers in the region of Soure and Salvaterrarefer to the winter as the period when Trichechus spp. aremost abundant in the region (Sousa, 2008).
‘Winter’* 28 (93)
"They go out to sea in the winter, in the summer, they keepto the river" (...) "they don’t like a lot of noise, they are likepirarucu." (Interview 88)
‘Summer’* 2 (7)
*In the Marajó region, the dry season is referred to as the summer, and the rainy season, as the winter.
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e6058
salinity and/or the rainy season as themost frequent environmentalcharacteristics. The village of Joanes and its surroundings (Jubimand Pilão, see Fig. 2) was the area identified as the most suitable toreceive animals under semi-captive conditions.
4. Discussion and conclusions
Based on an expedition to northern Brazil in search of infor-mation on manatees, Domning (1981) reported that these mam-mals were absent from the eastern coast of Marajó Island. However,in the 1990s, Luna et al. (2008b) confirmed the occurrence of theseanimals on the island, and Sousa (2008) reported two sightings onseparate days at Soure and two beached animals in Salvaterra(Sousa et al., 2010). Two beached animals were also observedduring the present study, which confirmed the occurrence ofmanatees in the region. The vast majority of the fishermen inter-viewed during the study acknowledged having seen these animalswithin the study area, either alive or dead, indicating a high level oflocal knowledge with regard to these mammals.
In fact, the richness of the details provided by the intervieweesin their descriptions of the morphological characteristics of themanatees, both internal and external, provides good evidence ofthe reliability of the presented information. The east coast ofMarajó Island is locatedwithin the estuary of the Amazon River andis assumed to be the only area of potential sympatry between
T. manatus and T. inunguis (Domning, 1981). Thus, the ability of thefishermen to distinguish between the two species based on theirmorphological characteristics (e.g., the presence of nails inT. manatus and the absence of nails and presence of a whitishventral patch in T. inunguis), was evaluated.
While the interviewees were able to describe a manatee satis-factorily, they were unable to differentiate the two species. Thismay be a result of the discreet behavior of the animals, as only havetheir snouts and occasionally their backs are commonly out of thewater, making it almost impossible to differentiate the speciesbased on casual observation. However, even the subjects who hadhad contact with the carcasses of dead manatees, and wouldtherefore have been able to inspect the animals more closely, wereunable to distinguish the two species.
The distribution of the localities at whichmanatees occurwithinthe study area is most likely influenced by specific environmentalfactors. Hence, the interviews also focused on the places where theanimals could be found, to better understand their sighting pat-terns. Most of the records were, in fact, concentrated in the mu-nicipality of Salvaterra. This may be related to two factors: theproximity of these localities to the places where the interviewswere conducted and their environmental characteristics.
In general, Salvaterra presents more favorable conditions for theoccurrence of manatees, including (i) the distribution of feedingresources (Alves, 2007; Arraut et al., 2010; Colares and Calares,
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e60 59
2002; Deutsch et al., 2003; Hartman, 1979; Montoya-Ospina et al.,2000; Oliveira-Gómez and Mellinck, 2005; Paludo, 1998); (ii) calmwater (isolated from natural hydrodynamics or anthropogenicdisturbance) (Alves, 2007; Arraut et al., 2010; Lima et al., 2005;Luna et al., 2008a; Smith, 1993); and (iii) the proximity of creeks(estuaries) for T. manatus (Hartman, 1979; Husar, 1977; Lefebvreet al., 2001; Lima et al., 2005; Marmontel et al., 1992; Montoya-Ospina et al., 2000; O‘Shea and Kochman, 1990; Oliveira-Gómezand Mellinck, 2005).
During the present study, most of the recorded sightingsreferred to the animals’ foraging behavior, which is understandable,considering that they spend more than 5 h per day engaging in thisactivity (Best, 1981) and can ingest the equivalent of 20% of theirbody weight during this time (Smith, 1993). These exclusivelyherbivorous animals must migrate in search of food. In ChetumalBay in Mexico, Castelblanco-Martínez et al. (2011) observed thatT. manatus adapts to seasonal changes in the distribution of re-sources by traveling around the bay in search of food. In theAmazon basin, where the main seasonal pattern corresponds to thefluctuation of river levels, the feeding behavior of T. inunguis ismore selective during the rainy season (high water), when the di-versity of resources is greatest. The manatees may also migrate tofloodplain lakes, where there are more abundant feeding areas,returning to the river in the dry season, where the protectionagainst predators is greater (Arraut, 2010). In northeastern Brazil,T. manatus migrates primarily in search of foraging areas (Alves,2007; Costa, 2006; Luna, 2001). In this study, the recorded migra-tions were invariably related to the distribution of areas with thehighest concentrations of feeding resources, as confirmed by theinterviewed fishermen.
While Soure is dominated by mangroves, Salvaterra exhibitsthree main habitats e freshwater swamps, mangroves, and coastalrestinga (Monteiro, 1983). This may mean that Salvaterra offers amore abundant resource base, although in Mexico, Castelblanco-Martínez et al. (2011) found that T. manatus was associated withmangroves, to compensate for the reduced abundance of sea grasswithin the study area. A total of 33 plant species have been iden-tified in the intertidal zone along the northern coast of Marajó Is-land, 13 of which have been recorded in the diet of manatees(Sousa, 2011). Nine of these species were cited by the intervieweesas part of the manatees’ diet. While these animals have beenclassified as being strictly herbivorous, some of the fishermenindicated the possible occasional consumption of animal material.A number of authors have described the involuntary ingestion ofinvertebrates, crustaceans, and fish present in the aquatic vegeta-tion by manatees (Borges et al., 2008; Courbis and Worthy, 2003;O’Shea et al., 1991).
In this study, the presence of manatees within the study areawas strongly associated with the rainy season, when the salinity ofthe water is zero. The increase in sightings during this period maybe related to the arrival of T. inunguis, which is adapted to fresh-water conditions andwould likely travel back up the estuary duringthe dry season, leaving only T. manatus in the study area. However,there is no information on the salinity levels tolerated byT. inunguis, and the salinity in the study area is actually relativelylow, never exceeding 7.7.
One of the difficulties facing T. manatus populations in theBrazilian northeast is the restricted access tomany estuaries, whichoften forces pregnant females to give birth in unprotected areas. Inthe Amazon region, however, the configuration of the coastline andthe abundance of well-preserved habitats may be far more favor-able to these animals, and the east coast of Marajó Island may be animportant nursery area for T. manatus, despite the small number ofreports of infants recorded in the present study. In T. inunguis, thepeak of births coincides with the beginning of the flood season in
the Amazon basin, when feeding resources are more abundant(Best, 1982). In the Brazilian northeast, the T. manatus breedingseason appears to occur between October and March (Alves, 2007;Lima et al., 1992), which is the period when the greatest number ofsightings were recorded on the east coast of Marajó Island. This isconsistent with the fact that in Pará, the greatest number ofbeached infants are recorded during the first half of the year (Sousa,2010).
The Amazon estuary may constitute a sympatric zone betweenthe habitats of T. inunguis and T. manatus (Domning, 1981), andDomning and Hayek (1986) described an animal from Pará withmorphological characteristics of both species (physically similar toT. inunguis, but with a nail on the pectoral fin) and other individualsfrom Suriname that appeared to be T. manatus but displayed nail-less fins, which is the diagnostic characteristic of T. inunguis. Lunaet al. (2008b) recorded the occurrence of both species on the eastcoast of Marajó Island. Beached and skeletal specimens confirm thissympatry. Vianna et al. (2006) also reported the occurrence of hy-brids in the vicinity of the Amazon estuary based on the observa-tion of two animals with traits of both sirenian species. Suchobservations emphasize the importance of the study area for theconservation of these two species of manatees in Brazil.
In this context, the knowledge of fishermen is a resource offundamental importance for the expansion of scientific databasesand for the development of effective strategies for managementand conservation (Huntington, 2000). It could be seen at the endof the interview program that the fishermen clearly understoodthe importance of the conservation of manatees, and could helpto identify the area with the greatest potential for the successfulreintroduction of captive animals. In addition to this work and thereintroductions on Marajó Island, the campaign “Threatened gi-ants: learn to conserve” was implemented, in which lectures andrecreational activities are conducted in the communities sur-rounding the town of Vila de Joanes. These activities havecontributed to a cooperative agreement established informallyamong researchers and the fishing community, thus increasingthe flow of information on strandings and sightings of manatees.It is believed that this partnership will remain during theimplementation of the semi-captive area and the release ofmanatees as well as assisting in the monitoring and surveillanceof animals post-release. The National Coastal Management(PNGC) program is not involved the study area directly and onlyfocuses on the towns of Salvaterra and Soure. However, the Na-tional Action Plan for Sirenian Conservation (PAN Sirenia) iden-tified northern Brazil as a priority area for the development ofconservation measures for the management of populations ofmanatees. These plans should also be decisive for the preserva-tion of species and their habitats along the northern coast ofBrazil.
Acknowledgments
This work was financially supported by the Fundação GrupoBoticário and by scholarships from FAPESPA/Vale concert to M.E.M.Sousa. We are very grateful to all of the fishermen on the Island ofMarajó for the many conversations over the years.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.ocecoaman.2013.08.016.
M.E.M. Sousa et al. / Ocean & Coastal Management 86 (2013) 53e6060
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