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Effectiviteit van akoestische afschrikmiddelen (pingers)___________________________

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Effectiveness of Acoustic Deterrent Devices (pingers)

Richard Franse Universiteit Leiden

Centrum voor Milieuwetenschappen Leiden Juli 2005


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Contents Abstract ............................................................................................................................... 3 Introduction......................................................................................................................... 4 Methods............................................................................................................................... 5 Results................................................................................................................................. 6

The Harbour Porpoise ..................................................................................................... 6 Bottlenose Dolphin ......................................................................................................... 9 Pinger ............................................................................................................................ 10

What is a pinger? ...................................................................................................... 10 Sound ........................................................................................................................ 10 Audiogram of a harbour porpoise / bottlenose dolphin ............................................ 10 Pingers....................................................................................................................... 11 Possible ways in which a pinger can work ............................................................... 12

Possible by-effects / side effects of pinger use ............................................................. 13 Reduction fishing effort ............................................................................................ 13 Habitat exclusion ...................................................................................................... 13 Hearing damage / background noise......................................................................... 14 Habituation................................................................................................................ 15 Dinner bell-effect ...................................................................................................... 16

Regulation ..................................................................................................................... 17 American regulation.................................................................................................. 17 EU regulation ............................................................................................................ 18 EU pinger specifications ........................................................................................... 20

SaveWave Dolphin Savers............................................................................................ 22 Conclusions / Recommendations...................................................................................... 23

Conclusions................................................................................................................... 23 Recommendations / advice ........................................................................................... 24

Acknowledgements........................................................................................................... 25 Literature........................................................................................................................... 26 Annexes............................................................................................................................. 31


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Abstract Bottlenose dolphins and porpoises are regular victims of bycatch. The cause of the bycatch is the fact that cetaceans are coming to close to the fishing nets and got strangled. Once strangled in the fishing nets the animals suffocate and in an attempt to break loose they damage the nets, which means economical damage for the fishermen. One solution to prevent bycatch is the use of pingers. Pingers are devices that produces ultrasound. This ultrasound must keep the bottlenose dolphins and porpoises away from the nets. A Dutch company, SaveWave, produces a new type of pingers, so called ‘Dolphin Savers’. Pingers in general are a recent development, therefore this study tries to determine the pinger effectiveness. In order to answer the question of pinger effectiveness, first three sub questions need to be answered which discuss the working of pingers, the side-effects of pingers and the regulation the pinger to which the pinger has to comply. For answering the different subquestions, a literature survey is carried out. Several different sources such as scientific publications and articles, European and national regulations and interviews, were used. The literature survey came up with the following result: The pinger is functional, it keeps bottlenose dolphins and harbour porpoises away from the fishing nets, however it is not certain if pinger will be effective on the long term. This because little is known about pingers. In which way the pinger works is still unknown. A number of side-effects can occur when using pingers, such as habitat exclusion, habituation and hearing damage. A reduction of fishing effort was not a side-effect, the most important prey-species of the bottlenose dolphin and harbour porpoise did not react on the pingers. Recent EU-regulation made pingers mandatory in certain high-risk fisheries (bottom-set gillnet fisheries and entanglement nets). The conclusive recommendation is pingers can be applied, only for a period of two years. After these two years there has to be an evaluation of pinger effectiveness, this is most important. A monitoring scheme is crucial, in this way the effectiveness of pingers can be controlled.


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Introduction Bottlenose dolphins and porpoises are regular victims of bycatch. According to the Whale and Dolphin Conservation Society (WDCS) there is a yearly bycatch of 300,000 cetaceans worldwide. In an article of Read et al. (2003) an estimate is made of the yearly bycatch of cetaceans worldwide. The total amount of bycatch is estimated to be 307,753 ± 98,303 individuals. From the harbour porpoise, a widespread European cetacean, it is estimated that there is a bycatch of around 10,000 individuals in the northern European seas alone. Because of the large scale, bycatch is a serious threat to the existence of a number of dolphin species. In a number of populations the number of dolphins is rapidly declining. The cause of the bycatch is the fact that cetaceans are coming to close to the fishing nets and got entangled. An important reason why the animals come to close is because they feed on the fish caught in the nets. Another important reason for the entanglement is the animals are too late in observing the fishing nets, so they can not avoid the nets. Once entangled in the fishing nets the animals suffocate and in an attempt to break loose they damage the nets. The reparation of these damaged nets is costing the fishing industry much time and money. This situation does not favour the relationship between cetaceans and fishermen. To improve the relationship between cetaceans and fishermen, the bycatch has to be reduced. To achieve this reduction the bottlenose dolphins and porpoises must be kept away from the fishing nets, there are a few possibilities to accomplish this. One of the possibilities is to impregnate the fishing nets with iron oxide, a disadvantage of this method is a reduction in fishing effort (Larsen et al., 2002). Other option is to close certain areas for fishery, this is a functional measure, but has an important disadvantage. Out of social and economic perspective it is hard to achieve. Another option is to make the fishing nets more notable for the dolphins. This can be achieved in two ways, the passive way by reflectors, or the active way by “pingers”. Pingers are devices that produce ultrasound. This ultrasound is to keep the bottlenose dolphins and porpoises away from the nets. The Dutch company SaveWave produces a new type of pingers, the so called ‘Dolphin Savers’. These pingers are available in a number of varieties, and they can vary in pulse duration, interpulse interval and fundamental frequencies. This has to prevent habituation to the pinger sound. Pingers in general are a relatively new product, which not much is known about. Therefore this research tries to find an answer the following question:

• Is the pinger, i.e. the ‘Dolphin Saver’, effective? Does it keep harbour porpoises and bottlenose dolphins away from the fishing nets?

In order to answer this question, first three sub questions need to be answered: • How does a pinger work? • Are there any by-effects / side-effects of (the use of) pingers • To which regulation the pinger has to comply?


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Methods In order to find out the effectiveness of the pingers a literature survey is carried out. In this survey literature from several disciplines are combined to get an answer to the main question. Before answering this question, first three subquestions need to be answered. These subquestions discuss each another part of the problem, the working of pingers, the by-effects of using pingers and European Union (EU) regulation concerning pingers. These sub questions needed an answer first, before we could answer the main question. Answering the different subquestions, several different sources such as scientific publications and articles, European and national regulations and interviews, were used. In this way the questions could be answered completely. The literature survey resulted in a broad range of findings, all these findings were used to determine the answers to the subquestions. After combining the answers to the subquestions the effectiveness of pingers could be determined and an advice be given.


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Results Before answering the questions, first there is an insight in the biology of the harbour porpoise and the bottlenose dolphin.

The Harbour Porpoise Harbour porpoises (Phocoena phocoena) belong to a group of marine mammals called the cetaceans, of which there are more than 80 known species. Cetaceans can be further classified into two distinct sub-orders, consisting of the toothed whales, the Odontocetes, and those who posses baleens instead of teeth, the Mysticetes. Harbour porpoises belong to the group of Odontocetes. The harbour porpoise is the smallest cetacean and is growing to an average length of 1.55 meters and a mass of 55 kilograms. Female porpoises are longer then males. Porpoises can live for as long as twenty years, they become physically mature at an age of five years for males and seven years for females and. Both males and females become sexually mature at an age of three to four years. When they are sexually mature they usually produce one calf every year. Gestation takes 10.5 months, and calving takes place between May and August. The calves are weaned before they reach 12 months and take small solid food when they are just a few months old. Porpoises feed on herring (Clupea harengus; Dutch name: haring), capelin (Mallotus villosus; Dutch name: Lodde), pollack (Pollachius virens; Dutch name: Zwarte Koolvis) and hake (Merluccius bilinearis; Dutch name: heek). The common name of the harbour porpoise is derived from their regular appearance in bays and harbours. Harbour porpoises are a coastal species inhabiting temperate and artic waters in the Northern hemisphere. Generally they inhabit shallow waters in the North Atlantic and North Pacific region with a depth of less then 200 meters (figure 1). In Europe the harbour porpoises inhabit the Atlantic Ocean, the Artic Ocean, the North Sea, the Baltic Sea and the Black Sea. They are normally found individually or in groups of two to three and six to eight individuals. Larger aggregations can also occur as a result of feeding. Porpoise populations throughout their range continue to be threatened by incidental mortality in many fisheries. In Europe the harbour porpoise bycatch from bottom-set gill nets is estimated to be over 7000 animals annually in the North Sea (Joint Nature Conservation Committee: Marine Mammal Bycatch). Many harbour porpoise populations around the world have been depleted through bycatch in fisheries. Harbour porpoises are listed in the IUCN Red List of Threatened Species as vulnerable throughout their range.


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Figure 1: Global spreading harbour porpoise (Phocoena phocoena). Source: Culik, 2002.

Figure 2: Spreading harbour porpoise (Phocoena phocoena) in Europe. Source: www.natuurinformatie.nl/EUCC.


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Figure 3: Global spreading bottlenose dolphin (Tursiops truncatus). Source: Culik, 2002.

Figure 4: Spreading bottlenose dolphin (Tursiops truncatus) in Europe. Source: www.natuurinformatie.nl/EUCC.


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Bottlenose Dolphin Bottlenose dolphins (Tursiops truncatus) also belong to the cetaceans and the subgroup Odontocetes. The common name of the bottlenose dolphin is derived from the beak, which apparently resembles the top of a bottle. Bottlenose dolphins are medium-sized cetaceans, they measure between 2 and 3.8 meters and their weights range from 220 to 500 kilograms, with a mean of 242 kilograms. Male Bottlenose dolphins are larger then females. Bottlenose Dolphins can live for as long as 25 to 50 years, with a mean of 30 years, and they become physically mature at an age of approximately 13 years. A bottlenose dolphin becomes sexually mature at nine to thirteen years for males and five to twelve years for females. When they are sexually mature they produces young every two to three years. Gestation takes 12 months, and calving takes place in spring and summer or spring and autumn. The calves are weaned for 18 months, but young begin to eat solid food when less than 6 months old. Bottlenose dolphins feed mainly on mullet (Chelon labrosus; Dutch name: harder), anchovies (Engraulis spp.; Dutch name: ansjovis), herring (Clupea harengus; Dutch name: haring), cod (Gadus morhua; Dutch name: Kabeljauw), menhaden (Brevoortia spp.; Dutch name: menhaden), capelin (Mallotus villosus; Dutch name: Lodde) and salmon (Salmoninae spp.; Dutch name: zalm). Bottlenose dolphins are found primarily in coastal and inshore regions of tropical and temperate waters of the world (figure 2), and population density seems to be higher near shore. In Europe they inhabit the Atlantic ocean, the Artic Ocean, the North Sea, the Baltic Sea, the Mediterranean Sea and the Black Sea. Bottlenose dolphins have been reported individually, but most of the time they appear in groups of between 10-100 inshore and offshore there have been seen large herds of several hundred to a thousand individuals. Populations of Bottlenose dolphins are threatened throughout their range by incidental mortality in many fisheries. In Europe acute conservation problems occur in the Mediterranean Sea and the Black Sea according to the IUCN-report. Populations in these areas declined seriously. One of the reasons is entrapment in fishing gear, particularly in gillnets.


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Pinger

What is a pinger? By the defining the term pinger it is important to make a difference between an ‘Acoustic Deterrent Device (ADD; Dutch: akoestisch afschrikapparaat)' and a ‘Acoustic Harassment Device (AHD)'. An AHD has the intention to discomfort or harass the animal, so they stay away from the fish farms and other large assemblies of fish, for instance fishing nets. The AHD is especially used to prevent depredation by pinnipeds. Therefore an AHD has a relative high source level (>185 dB re 1 µPa at 1 m) and emits signals in the middle to high frequencies (5 – 30 kHz; Reeves et al., 2001). An ADD is a device with a low intensity (source level: < 150 dB re 1 µPa at 1 m) and emits signal in the middle to high frequencies (2.5 – 10 kHz) with higher harmonic frequencies (up to 160 – 180 kHz). Pingers are designed to prevent bycatch of small cetaceans (Reeves et al., 1996; Reeves et al., 2001). Pingers use ultrasound to keep the dolphins away from the fishing nets.

Sound Pingers transmit ultrasound, to understand how pingers work, first it is necessary to understand the definition of ultrasound and the behaviour of sound in water. Ultrasonic sound ‘Sonic’ is a term derived from the human hearing range (20 Hz – 20 kHz). Frequencies outside this range are called infrasonic or ultrasonic. Below 20 Hz a frequency is called infrasonic, below the human hearing range or ultrasonic. Above 20 kHz a frequency is called ultrasonic, above the human hearing range (Ketten, 1998). Sound in water The speed of sound is variable, it depends on the density of the medium. Because water is denser than air, sound in water travels faster. In air the speed of sound is 340 meter per second. The speed of sound in water is 1530 meter per second. So in water sound speed is 4.5 times faster. Except the speed of sound also the sound intensity is different. Comparing air vs. underwater sound intensities, the numerical value of the water sound pressure level must be reduced by ~ 61.5 dB to be comparable numerically to an intensity level reported in air. For example: 200 dB in water is comparable to138.5 dB in air (Ketten, 1998).

Audiogram of a harbour porpoise / bottlenose dolphin For an effective pinger it is necessary to determine the hearing range of the harbour porpoise and bottlenose dolphin. This can be defined in an audiogram. Kastelein (2002) made such an audiogram for the harbour porpoise (figure 5). Harbour porpoises can hear sounds with frequencies from 16 kHz up to 140 kHz, with a reduced sensitivity at 64


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Figure 5: Audiogram harbour porpoise and bottlenose dolphin. kHz. Most sensitive is the harbour porpoise for frequencies from 100 up to 140 kHz, this resembles the frequency which they use for their echolocation pulses. For the bottlenose dolphin there is also an audiogram (figure 5). They can hear frequencies from 75 Hz up to 150 kHz (Johnson, 1967). The bottlenose dolphins are most sensitive for frequencies from 15 up to 110 kHz. The peak frequency for their echolocation pulses is 100 kHz (Au, 1993).

Pingers Pingers are designed to keep the dolphins away from fishing nets. To be effective, the pingers need to be audible. Therefore pingers emit pulses in the sensitive hearing range of the harbour porpoises and bottlenose dolphins. This sensitive range is different for different species. Pingers (depended on type) emit pulses which vary from 5 kHz up to 160 kHz, with harmonic frequencies up to 180 kHz. A harmonic frequency is a frequency or a mode of vibration (or a component of a sound) whose frequency is a whole-numbered multiple of the fundamental frequency, including the fundamental. These harmonic frequencies are deterrent for the dolphins. The pulses are emitted as sweeps. A sweep is a tone which varies in frequency. Sweeps are unpleasant for the most human and animals, and therefore the pinger is more effective (Kastelein, pers. comm., Lockyer et al., 2001).


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The sound pressure is determined by Source Level (SL). The SL measures the sound at 1 meter distance at a pressure of 1 microPascal ( = SL: re 1 µPa @ 1m). Usually this the SL varies between 0 and 200/300 (Kastelein, pers. comm.). It is also important that pinger use does not have any negative consequences for the fishing effort and pingers have to be easy in use. Else the fishermen will avoid the use of pingers. Another important issue are the costs of the pinger, when the pingers are to expensive, fishermen will not use the pingers (Larsen, 2000).

Possible ways in which a pinger can work For estimating pinger effectiveness it is necessary to know in which way pingers do work. Results of several researches (Kraus, 1999; Stone et al., 1997; Kastelein; Trippel et al. 1999, SMRU et al., 2001; Larsen et al., 2000; Barlow & Cameron, 2003) show pingers do work, however it is unknown how pingers work. Central to the question of pinger effectiveness is understanding how and why they work. There are an number of hypothesis which try to explain why pingers work (Kraus 1999).

- Jamming of the animals’ sonar

This hypothesis suggests it is possible that a broadband sound occupying the sonar frequencies of the target species might drown out sonar clicks, and render the animals acoustically blind. In an oceanic environment with a poor visibility, dolphins avoid such a signal because they are depending on their echolocation.

- Avoidance by prey species Another possibility for the reduction in bycatch may be the avoidance by prey species. This hypothesis in based on research by Mann (1997), Kraus et al. (1997) and Kraus (1999) and Gearin et al. 1994. Because herring is a primary food for the harbour porpoise, researchers worried that the reduced porpoise bycatch was due to the pinger effect on the prey species (herring) and not necessarily on porpoise. If the pingers do work in this way, they are not functional in practice, because the pinger deters the fish. This has a negative impact on the fishing effort, and therefore it is not acceptable for the fishermen.

- Alerting of harbour porpoise / bottlenose dolphin One of the causes for entanglement in fishing nets is that they see the nets too late. Kastelein et al. (2000) states the 90% detection distance of bottom set gillnets is for the harbour porpoise between 3 and 6 meter, when they approach the nets in an straight angle and with little background noise. For bottlenose dolphins the detection distance was between 25 and 55 meter. When both the bottlenose dolphin and harbour porpoise approach the fishing net in a straight angle, the detection distance is decreased. Kraus et al. (1995) and Goodson et al. (1994) stated that small cetacean get entangled by moving without continuous use of their echolocation. This hypothesis states that when the dolphins hear the sounds, they interrogate their surroundings, detect the net and avoid it. When the dolphin hears the sound of the pinger, it will investigate the environment to find


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out what made the sound. When investigating the environment the dolphin will detect the fishing nets and avoid it. On the other hand there is a risk of a dinner bell-effect. A dinner bell-effect means the pingers attract dolphins, instead of keeping them away.

- Annoying This hypothesis states that dolphins avoid pingers the way humans avoid static or unpleasant noise. Given the high tolerance of urban humans and animals for traffic and construction noise, it is likely that if pingers are annoying, there is a good argument for believing pingers will lose their effectiveness over time and the animals become habituated to the sound of the pinger.

- Startle The startle hypothesis states that dolphin get startled and flee when hearing the sound of a pinger, a response likely to diminish if animals become habituated to the sound. This could mean that pinger would only be effective until the animals stopped being startled or scared, at which point they would not longer avoid nets.

Of all these hypotheses, some are already retrieved. According to SaveWave, their pinger disturbs the echolocation of the dolphins. This is not likely according to Ron Kastelein (pers. comm.) en Wim Verboom (pers. comm.). Echolocation signals are send straight forwards, and are also received from that direction. The pinger would only work if the dolphin swims straight to the pinger, this almost never happens. In this situation the pinger will not have any effect on the amount of dolphin bycatch. Also the prey-avoidance hypothesis is not possible. Several researches (Trippel et al., 1999; Wilson & Dill, 2002; Kastelein, pers. comm.) has proven that pingers have no impact on an important prey species of the harbour porpoise and bottlenose dolphin, the herring (Clupea harengus). Recent research shows that the conclusion herring can hear ultrasound, is probably based on a mistake (Verboom, pers. comm.). Probably pingers work by means of annoyance, alerting or startle, habituation is a realistic threat to the effectiveness of pingers.

Possible by-effects / side effects of pinger use

Reduction fishing effort One of the possible side effects is the avoidance of pingers by prey species. Several researches (Wilson & Dill, 2002; Culik et al., 2001; Trippel et al., 1999; Kastelein, pers. comm.) found out that pingers do not have any effect on the fishing effort. So based on these researches there can be concluded this side effect is not proven.

Habitat exclusion Another possible side effect is the exclusion of dolphins from their habitat or important parts of it (Goodson et al., 1997; Laake et al., 1998; Gearin et al., 2000; Culik et al., 2001; Cox et al., 2001; Berggren et al., 2002; Larsen 1999; ACCOBAMS 2002). This is


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Figure 6: Habitat exclusion a great risk, especially in river mouths (figure 6), because there are few possibilities to avoid the pingers. Exclusion from (parts of) the dolphins habitat could have important consequences when it is concerning for example a foraging or mating area. There is a possibility that SaveWave High Impact Saver cause habitat exclusion for harbour porpoises in the North Sea (Kastelein, pers. comm.). There is also a risk the pingers will get loose from the fishing nets and exclude the dolphin from a certain area for a longer period (CEC, 2002).

Hearing damage / background noise An effective pinger emits sounds which can be heard by the dolphins. A problem is that all dolphins have other optimal hearing levels; also sound level is an important factor. A pulse with a certain source level can be hardly audible for one dolphin species (for example: bottlenose dolphin), while for other dolphin species (for example: harbour porpoise) the sound will damage their ear, although it has the same sound pressure. (figure 7). Dolphin species are not spatial separated, therefore it is hard to make a pinger which will work on every dolphin species (Verboom, pers. comm.). When a dolphin comes too close to a pinger, hearing damage can occur. Hearing damage has important consequences for dolphins because they dependent on echolocation. Gordon & Northridge (2002) stated hearing damage will occur when a dolphin comes in a range of 2 to 3 meter of an active pinger. According to Taylor et al. (1997) the worst case is hearing damage at a distance of 30 meter. Dolphins which are regularly exposed


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Figure 7: Differences hearing levels harbour porpoise and bottlenose dolphins. (Verboom, pers. comm.). to pingers can also get hearing damage (Reeves, 2001). Hearing damage can, if it is serious (physical damage), lead to death. Another problem which is connected to hearing damage is background noise. When there is much background noise, the dolphin will not hear the reflection of the echolocation pulse. In this case the dolphin will not be able to catch as much preys as it does usually (Wim Verboom pers. comm.; Gordon & Northridge, 2002). The same situation will occur when the dolphin’s ear is damaged.

Habituation The most mentioned side effect is habituation (Barlow & Cameron, 2003; Cox et al, 2001; Dawson et al, 1998; Gordon & Northridge, 2002; Kraus, 1999; Laake et al., 1998; Larsen, 1999; Reeves et al, 2001; Richardson et al, 1995; Trippel et al, 1999). Habituation means the dolphins get used to the pinger sound, and will ignore it. In that case the pingers have no value. Little is known about habituation and there have been a number of researches but they all had a limited time span. To investigate habituation, longer research (several months) is necessary. Because the most likely explanation, the startle effect, it is logical habituation occurs. Because this is a great threat to the effectiveness of the pinger it is desirable to know if and when habituation occurs. Not only for sea environment, but also for the investments the fishermen have to make because of the European regulations.


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Dinner bell-effect Dinner bell-effect means the dolphins are attracted by pingers, in this way the pingers work inversed. In this situation the dolphins learn they can find food at the source of the sound; the pinger. Little is known about the dinner bell-effect. To find out if the dinner bell-effect is real threat for using pingers, more research has to be done. It is important such a research will be started as soon as possible, because in case of this effect the pinger attracts dolphins to the fishing nets, instead of keep them away. At this moment the dinner bell-effect occurs especially with pinnipeds (Mate & Harvey, 1986).


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Regulation Regulations concerning pingers can be divided into American regulations and European regulations. Both regulations will be explained.

American regulation American pingers have to suffice to regulations (NOAA). This regulations describes the specifications (table 1): A pinger is an acoustic deterrent device which, when immersed in water, broadcasts a 10 kHz (±2 kHz) sound at 132 dB (±4 dB) re 1 micropascal at 1 m, lasting 300 milliseconds (±15 milliseconds), and repeating every 4 seconds (± 0.2 seconds). Furthermore the pingers may only be used in water with depth of more than 600 feet (182,88 meter). Pingers are designed to produce a sound level which at 328 feet (100 meter) is 15 dB higher than background noise. ‘American’ pingers appear to be the most described pingers in scientific literature, probably because these pingers exist for a longer time. Source Levels (SL) re 1 µPa @ 1m 132 dB (±4 dB) Fundamental frequency 10 kHz (±2 kHz) Pulse duration 300 milliseconds (±15 milliseconds) Interpulse interval 4 seconds (± 0,2 seconds) Spacing between two acoustic deterrent devices along nets

300 feet (91,44 meter)

Table 1: American pinger specifications


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EU regulation The council of the European Union (EU) has adopted the following regulation on April 26th 2004, called: COUNCIL REGULATION (EC) No 812/2004 of 26.4.2004, laying down measures concerning incidental catches of cetaceans in fisheries and amending Regulation (EC) No 88/98 This regulation lays down measures aimed at mitigating incidental catches of cetaceans. The regulation is mandatory in the North Sea, Celtic Sea, The Channel and a part of the Baltic Sea. The main part of the regulation is the protection of harbour porpoises. The annual bycatch level in the regulation area is estimated at 9000 – 10,000 individuals. This number can be divided into three numbers for three areas:

- Baltic Sea: 7 (Berggren et al. 2002). This number seems a little low, but the harbour porpoise population size for the Baltic sea is estimated at 600 individuals (HELCOM). The total allowable bycatch for this population is 2 individuals, else the Baltic Sea population will probably extinct within 20 years. The number bycatch in the Baltic Sea is estimated at 7 (IFAW), more than two times the total allowable bycatch.

- Celtic Sea: The bycatch in this area is estimated at more than 2,000 harbour porpoises a year (UNEP).

- North Sea: The bycatch in this area is estimated at least 7,000 harbour porpoises a year (OSPAR).

Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora gives strict protection status to cetaceans and requires the member states of the European Union to undertake surveillance of the conservation status of these species. For the protection of cetaceans a regulation is adopted: COUNCIL REGULATION (EC) No 812/2004 of 26.4.2004 laying down measures concerning incidental catches of cetaceans in fisheries and amending Regulation (EC) No 88/98. This regulation is divided into three parts, a ban on the use of drift nets in the Baltic Sea, observers on board fishing vessels and the use of acoustic deterrent devices (pingers). An overview of the regulation for pingers:

- For vessels with a length of 12 meters or over it is prohibited to use bottom-set gillnets and entangling nets without the simultaneous use of active acoustic deterrent devices.

- The master of the fishing vessels shall ensure the acoustic deterrent devices are fully operational when setting the gear.

- Member states of the European Union shall take necessary steps to monitor and assess, by means of scientific studies or pilot projects, the effect of pinger use over time in the fisheries and areas concerned.

- Acoustic deterrent devices shall comply with one set of the technical specifications and conditions given in the regulation.


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- Member states of the European Union may authorise the temporary use of acoustic deterrent devices which do not fulfil the technical specifications or conditions of use defined in the regulation, provided their effect on the reduction of incidental catches of cetaceans has been sufficiently documented. An authorisation shall be valid for no more than two years.

Pinger effectiveness is proven in a number of scientific studies (Kraus, 1999; Stone et al., 1997; Kastelein et al., 1995 Kastelein et al., 2001; Trippel et al. 1999, SMRU et al., 2001; Larsen et al., 2000; Barlow & Cameron, 2003). However the ICES-report 2002, on which the European regulation is based, states effectiveness and side-effects are still uncertain. Side-effects mentioned in this report are: effect on preyfish species, habitat exclusion and habituation. The ICES-report indicates the pingers can be used as a short-term solution, while at the same time research has to be done for medium- and long-term mitigation measures. Also ASCOBANS and IWC Scientific Committee consider pinger deployment as a short-term approach (IWC, 2002). Furthermore it is likely the efficiency of pingers is different for every cetacean species. For this reason more research is needed to get a better insight in the consequences of pinger use on the long term. Except for the uncertainty of pinger effectiveness and side side-effects, there are a few more critics on the EU regulation:

- In the original proposal was recommended that all fishing boats were required to use pingers, in the final regulation only the fishing boats of twelve meters or longer were required to use pingers.

- There also is criticism on the implementation of the observers. Fisheries which are mandatory to use pingers are not mandatory for the use of observers. When observers were mandatory on fishing boats with pingers, there could be determined if the pingers are effective, and determined if there are any side-effects.

- The date for the implementation of pinger regulation is changed from June 1st 2004 in the original proposal to June 1st 2005, January 1st 2006 and January 1st 2007 in the final regulation. Especially criticised is the date for implementation in a part of the Baltic Sea (January 1st 2007), because of the threatened status of the harbour porpoise population.

- There has not been enough research done on the (side-) effects of pinger use. For example, there is a possibility pinger sounds have effects on animals other than cetaceans. These effects could be harmful, there is an example of a sea snail which can not reproduce when the sound level (of the background noise) is too high (Verboom, pers. comm.).

For an evaluation of the EU-regulation the member should report annually on the use of pingers and the implementation of the on-board observer programmes and include all information collected on the incidental capture and killing of cetaceans in fisheries.


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EU pinger specifications The EU pinger specifications can be found in the discussed EU regulation No. 812/2004. In Annex II of this regulation the pinger specifications can be found: Set 1 Set 2

Signal characteristics Signal synthesis Digital Analogue Tonal/wide band Wide band / Tonal Tonal Source Level (max – min) re 1 µPa @ 1m

145 dB 130 – 150 dB

Fundamental frequency

a) 20 – 160 kHz wide band sweeps

b) 10 kHz tonal

10 kHz

High-frequency harmonics

Yes Yes

Pulse duration (nominal)

300 ms 300 ms

Interpulse interval

a) 4 – 30 seconds, randomised

b) 4 seconds

4 seconds

Implementation characteristics Maximum spacing between two acoustic deterrent devices along nets

200 m, with one acoustic device fixed at each end of the net (or combination of nets attached together)


Table 2: EU pinger specifications As can be seen in this table, the second set of specifications shows great resemblance with the American pinger specifications. The first set of specifications shows great resemblance with the specifications of the Aquatec AQUAmark 100 pinger. De EU-regulation concerning the implementation of pingers is mandatory in a restricted area. In the map below can be seen where and when the EU-regulation is mandatory


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Figure 8: Areas EU-regulation


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SaveWave Dolphin Savers SaveWave is Dutch company located in Delft. SaveWave produces pingers called Dolphin Savers. Based on different studies of different researches SaveWave developed in collaboration with Dutch researchers and Cuckoo Company the Dolphin Saver. The Dolphin Saver is an acoustic deterrent device that can be easily attached to the fishing nets. As soon as is touches the water, it will start emitting ultrasonic signals. The development of the Dolphin Saver began in 1997 and took five years. In 2002 the dolphin Saver came into the commercial market. The Dolphin Saver differs from other pingers, because the Saver has randomized interpulse interval, pulse duration and fundamental frequency. The sound emitted by the pinger covers the total spectrum of the dolphin hearing. In this way everything has been done to prevent habituation by as much randomization as possible. There are a few types of Dolphin Savers, the High Impact Saver and Endurance Saver, these are the most important types. The High Impact Saver is designed to the keep inquisitive bottlenose dolphins away from the fishing nets to prevent the depredation of the nets. The SaveWave pinger is especially suitable for the Mediterranean Sea because bottlenose dolphins also are living there. The Endurance Saver is designed for the more anxious harbour porpoise. This pinger is less suitable for the bottlenose dolphin. Because the harbour porpoise lives in the North Sea, this pinger is especially suitable for use in the North Sea. Specifications High Impact Saver and Endurance Saver High Impact Saver Endurance Saver

Signal characteristics Signal synthesis Digital Digital Tonal/wide band Wide band Wide band Source Level (max – min) re 1 µPa @ 1m

155 dB 140 dB


Black core: 5 – 30 kHz White core: 30 – 160 kHz

5 – 90 kHz


Yes, doubled and mirrored up to 180 kHz

Yes, doubled and mirrored up to 180 kHz


200 – 900 milliseconds randomized

200 – 400 milliseconds randomized

Interpulse interval

4 – 16 seconds randomized 4 – 30 seconds randomized

Implementation characteristics Maximum spacing between two acoustic deterrent devices along nets

200 meter 200 meter

Table 3: Specifications of the SaveWave High Impact Saver and the SaveWave Endurance Saver.


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Conclusions / Recommendations

Conclusions In order to answer the main question, first three sub questions need to be answered. The first sub question was how a pinger works. Answering this question it became clear that almost no research was done on how a pinger works. There were only a few hypotheses. Of these hypotheses the most plausible were: dolphins get startled and flee when hearing the sound of a pinger and dolphins are annoyed when hearing a pinger and therefore they avoid it. Several scientific studies pointed out habituation can occur. Therefore it is very likely that pingers are only short-term solutions. The functional lifespan of the pinger can be extended to by randomization. The moment of habituation is postponed by randomization and so the pinger has a longer lifespan. Because of the amount variables the SaveWave Dolphin Saver is an interesting possibility of an applicable pinger. The second sub question was if there are any side-effects when using pingers. A few side-effects are known or predicted. In the Kraus (1999) article a number of hypotheses were given for the possible side-effects of pingers. The most important are habitat exclusion, habituation, dinner bell-effect and hearing damage / background noise. In scientific articles little is known about the possible side-effects of pingers. Because side-effects only appear after some time, long term research is necessary, this will cost a large amount of money. However, there are some indications (Cox et al., 2001) habituation occurs. In other researches habituation is seen as a great threat to pinger effectiveness. There has also been a research to habitat exclusion (Goodson et al., 1997; Laake et al., 1998; Gearin et al., 2000; Culik et al., 2001; Cox et al., 2001; Berggren et al., 2002; Larsen 1999; ACCOBAMS, 2002), but it can be expected this effect will diminish, because of habituation. The third subquestion was to which regulation the pinger has to comply. The pinger has to comply with a number of demands. America already has a pinger regulation for a time. This regulation comes from the National Oceanic and Atmospheric Administration (NOAA). All American pingers have to comply with this regulation. Recently the EU (European Union) accepted regulation to lay down the incidental catches of cetaceans in fisheries. This regulation was implemented on July 1st 2004, and the use of pingers is a part of it. The allowed pinger specifications are broader than the American specifications. The EU-regulation is only mandatory in the North Sea, Celtic Sea, The Channel and a part of the Baltic Sea. After answering all the sub questions, now the main question will be answered. The main question was if the (SaveWave Dolphin Saver) pinger is effective and does it keep harbour porpoises and bottlenose dolphins away from the fishing nets. There can be concluded pingers are effective, it keeps the dolphins and harbour porpoises away from the fishing nets. However it is uncertain if the pinger will be a long-term solution to prevent bycatch of harbour porpoises and bottlenose dolphins (small cetaceans).


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Recommendations / advice The SaveWave pinger can be applied, only for a restricted period, for example two years. Most important is to continue researching the pinger (-effectiveness) and its side-effects. A monitoring scheme is very important, this is also an advice of organisations like ICES (International Council for the Exploration of the Sea), ASCOBANS (Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas) and the IWC (International Whaling Commission)(ICES, 2002). In this way the pinger effectiveness can be determined and monitored.


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Acknowledgements I want to thank Ruben Huele for his excellent supervision. I want to thank Aukje Coers, Sancia van der Meij and Nynke Osinga for their cooperation. I want to thank Peter Schilperoord for his help in translating this report. I want to thank Ron Kastelein (SEAMARCO) and Wim Verboom (TNO) for their cooperation and explanation. I want to thank Rick van Lent (SaveWave BV) for his cooperation.


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Kastelein, R. A., de Haan, D., Vaughan, N., Staal, C., & Schooneman, N. M. 2001. The influence of three acoustic alarms on the behaviour of harbour porpoises (Phocoena phocoena) in a floating pen. Marine Environmental Research, 52, 351–371. Kastelein, R. A., Bunskoek, P., Hagedoorn, M., Au, W. W. L., & de Haan, D. 2002. Audiogram of a harbour porpoise (Phocoena phocoena) measured with narrow-band frequency-modulated sounds. Journal of the Acoustical Society of America, 112, 334–344. Ketten, D. 1998. Marine mammal auditory systems: a summary of audiometric and anatomical data and its implications for underwater acoustic impacts. NOAA-TM-NMFS-SWFSC-256. 74p. Kraus, S.D., Read, A.J., Solow, A., Baldwin, K., Spradlin, T., Anderson, E., Williamson, J., 1997. Acoustic alarms reduce porpoise mortality. Nature 388, 525. Kraus, S. 1999. The once and future ping: Challenges for the use of acoustic deterrents in fisheries. Mar. Tech. Soc. J. 33(2):90-93. Laake, J., D. Rugh and L. Baraff. 1998. Observations of harbor porpoise in the vicinity of acoustic alarms on a set gill net. NOAA Technical Memorandum NMFS-AFSC-84. Larsen, F. 1999. The effect of acoustic alarms on the by-catch of harbour porpoises in the Danish North Sea gill net fishery. Paper SC/51/SM41, Scientific Committee of the IWC. 8 pp. Larsen, F. 2000. Improving the mechanism of pinger attachment for the Danish North Sea gillnet fishery. Paper SC/52/SM27, Scientific Committee of the IWC. 6 pp. Larsen, F. and Rye Hansen, J. 2000. On the potential effects of widespread use of pingers in the North Sea. Paper SC/52/SM28, Scientific Committee of the IWC. Larsen, F., Vinther, M. & Krog, C. 2002. Use of pingers in the Danish North Sea wreck net fishery. Paper SC/54/SM32, IWC Scientific Committee. 8 pp. Lockyer, C., Amundin, M., Desportes, G., and Goodson, A.D. 2001. The tail of EPIC. Final report of EPIC, Elimination of harbour porpoise incidental catches. EU Project DG XIV 97/0006. 249 pp. Mann, D.A., Lu, Z., Popper, A.N., 1997. A clupeid fish can detect ultrasound. Nature 389, 341. Mate, B. R. and J. T. Harvey ,1987. Acoustical deterrents in marine mammal conflicts with fisheries. Oregon Sea Grant Report ORESU-W-86-001. 116 pp.


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Taylor, V.J, Johnston, D.W. & Verboom, W.C. 1997. Acoustic Harassment Device (AHD) use in the aquaculture industry and implications for marine mammals. In: Proceeding Symposium on Bio-sonar and Bioacoustics, Loughborough University U.K Trippel, E.A., Strong, M.B., Terhune, J.M., Conway, J.D., 1999. Mitigation of harbour porpoise (Phocoena phocoena) by-catch in the gillnet fishery in the lower Bay of Fundy. Canadian Journal of Fisheries and Aquatic Science 56, 113–123. UNEP, 2001. Bycatch Limits Needed To Conserve Europe's Dolphins and Porpoises. http:// www.unep.org/Documents.multilingual/Default.asp?DocumentID=197&ArticleID=2814 WDCS, 2004. Dolphins Being Trawled To Extinction. http://www.wdcs.org.au/info_details.php?select=1074951000 Wilson, B. & Dill, L. M. 2002. Pacific herring respond to simulated odontocete echolocation sounds. Can. J. Fish. Aquat. Sci. 59, 542–553.


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Annexes Annex I Comparison EU pinger specifications


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Annex I: Comparison EU pinger specifications

EU pinger specification versus commercial available pingers specifications

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Manufacturer EU SaveWave BV Aquatec Sub Sea Ltd. Fumunda Marine Products

Airmar Technology Corporation

Models Set 1 Set 2 High Impact Saver

Long Line Saver

Endurance Saver

AQUAmark 100

AQUAmark 200

AQUAmark 210

AQUAmark 300

FMDP-2000

Gillnet Pinger

Signal characteristics

Signal synthesis Digital Analogue Digital Digital Digital Digital Digital Digital Digital Digital Digital

Tonal/ Wide band Wide band / Tonal Tonal Wide band Wide band Wide band Wide band / Tonal

Wide band / Tonal

Wide band / Tonal

Wide band / Tonal

Tonal Tonal

Source Levels (SL) (max – min) re 1 µPa @ 1m

145 dB 130 - 150 dB 155 dB 155 dB 140 dB 145 dB 145 dB 150 dB 145 dB 132 +/- 4 dB

132 +/- 4 dB


a) 20 - 160 kHz wide band sweeps

b) 10 kHz tonal

10 kHz Double signal 5 - 30 kHz and 30 - 160 kHz wide band sweeps, harmonics up to 180 kHz

Single signal 5 - 60 kHz wide band sweeps, harmonics up to 180 kHz

Single signal 5 - 90 kHz wide band sweeps, harmonics up to 180 kHz

20 - 60 kHz, harmonics up to 160 kHz

5 - 60 kHz, harmonics up to 160 kHz

5 - 60 kHz harmonics up to 160 kHz

10 kHz 10 kHz 10 kHz


Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes


300 ms 300 ms 200 - 900 ms randomized

200 - 400 ms randomized

200 - 400 ms randomized

200 - 300 ms 200 - 300 ms 50 - 300 ms 300 ms 300 ms 300 ms

Interpulse interval

a) 4 - 30 seconds randomized

b) 4 seconds

4 seconds 4 - 16 seconds randomized

4 - 16 seconds randomized

4 - 30 seconds randomized

4 - 30 seconds pseudo randomized

4 - 30 seconds pseudo randomized

4 - 30 seconds pseudo randomised

4 seconds 4 seconds 4 seconds

Implementation characteristics

Maximum spacing between two acoustic deterrent devices along nets



200 m 200 m 200 m 200 m 200 m 200 m 200 m 100 m 100 m

Note: EC COUNCIL REGULATION No 812/2004, Article 3.2: “… Member States may authorize the temporary use of acoustic deterrent devices which do not fulfil the technical specifications or conditions of use defined in Annex II, provided that their effect on the reduction of incidental catches of cetaceans has been sufficiently documented. An authorization shall be valid for no more than two years.” This table is based on the EC COUNCIL REGULATION No 812/2004 of 26.4.2004, Laying down measures concerning incidental catches of cetaceans in fisheries and amending Regulation (EC) No 88/98. Richard Franse, April 2005 (Email: [email protected])