Search The Database
Location | Gear | Catch | Technique | Bycatch species | Type | Results |
---|---|---|---|---|---|---|
Southwest England |
Gillnets
|
None reported |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | Fisheries observers and skippers tested the effectiveness of the Dolphin Dissuasive Device (DDD) as a bycatch mitigation tool for porpoises and dolphins. This study was conducted aboard fishing vessels in the Cornish over-12m static net sector fishery in the waters of Southwest England. DDD's were placed at the end nets. The DDD's caught significantly fewer porpoises but no significant difference in dolphin bycatch was observed. When bycatch rates were separated between short (up to 4 km) fleets and long (larger than 4 km) fleets, there was no significant difference in porpoise bycatch in the long fleet but there was in the short fleet. DDD's caught significantly fewer porpoises but no significant difference in dolphin bycatch was observed |
Cornwall |
Gillnets
|
Monkfish |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | Tests were conducted aboard small (<10 m long) static net fishing vessels targeting monkfish off the coast of Britain to determine the response of cetaceans to pingers. AQUAmark 100 pingers were positioned at 200 m intervals on the net and acoustic click detectors (C-PODs) were placed at the end of 1 km tiers of the net to determine the response of cetaceans to the pingers. Only one harbour porpoise was incidentally caught during these trials and there was a significant reduction in the number of porpoise clicks recorded at nets with pingers compared to those without. Additional tests were conducted to determine habituation. For these tests, modified pingers, active for alternate seven hour periods, were attached below click detectors at one site with strong tides and loud ambient noise and one at a quite site. The results of this part of the study showed the pinger effect was stronger at the quiet site and that were was no habituation. In addition, there was evidence of exclusion of porpoises following pinger use for as much as seven hours. One incidentally caught harbor porpoise; significant reduction in the number of porpoise clicks at nets with pingers. Pinger effects stronger at quiet sites; no habituation observed, exclusion of porpoises following pinger use for as much as 7 hrs |
Hawaii |
Hooks-and-Lines
|
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Summary study | An acoustic device designed to deter false killer whales from approaching longlines by reducing the whales' echolocation performance capabilities was tested on a trained false killer whale. The device, Longline Saver, produced a series of complex, broadband signals (1-250 kHz) at high intensity levels (up to 182 dB). The whale was asked to detect a target in the presense or abscence of the acoustic device. Initially, the device reduced the whale's echolocation performace to chance levels, however subsequent trials demonstrated improvement in echolocation. Initially disrupted false killer whale's echolocation performance capabilities |
|
Cornwall |
Gillnets
|
None reported |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | A study was conducted aboard the Cornish inshore gillnet fishery to determine if pingers could reduce porpoise and bottlenose dolphin bycatch, whether habituation to the pingers would reduce their effectiveness and how quickly porpoises and dolphins recolonise a pingered site after their removal. Vessels were equipped with passive acoustic monitoring systems that can recognize and log each animals click and AQUAmark 100 pingers were spaced 200 m apart on the nets. Control nets with no pingers were also used. There was a significant difference in the number of porpoise clicks between nets with and without pingers. There was no significant difference in the proportion of loud clicks logged when pingers were active and so the extent of displacement by pingers cannot be determined. In addition, there was no evidence of habituation to the pingers. It appears that porpoises take at least 7 hours to recolonise a pingered site. There were too few encounters with dolphins to determine the ability of pingers to reduce their bycatch or to determine how long recolonization will take. There was a significant difference in the number of porpoise clicks between nets with and without pingers, but the extent of displacement could not be determined. No evidence of habituation to the pingers. |
Queensland, Australia |
Gillnets
|
Sharks |
Acoustic deterrent devices
|
Megaptera novaeangliae (Humpback whale) | Field study in the wild | Acoustic pingers, Fumunda F3 (2.7 kHz) for humpback whales and F10 (10 kHz) for dolphins, were used on sharks nets within the Queensland Shark Control Program. Sound from the acoustic pingers was present for around 1.5 km beyond the nets. Humpback whales and dugons were able to hear the F3 pinger 90 m from the net and its two harmonic overtones (5.4 and 8.1 kHz) 10 and 210 m from the net respectively. The F10 pinger was audible to both species up to 130 m from the net. Dolphins could hear the F3 pinger 45 m from the net and it's two overtones 10 and 110 m from the net. The F10 pinger could be detected by dolphins up to 40 m from the net. Shark nets are currently fitted with 3 to 4 pingers per 200 m length of net and therefore appear to be adequate for detection by marine mammals swimming straight at the net and at a top speed. Humpback whales heard the F3 pinger 90 m from the net, they heard the F10 pinger was audible up to 130 m |
Queensland, Australia |
Gillnets
|
Sharks |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | Acoustic pingers, Fumunda F3 (2.7 kHz) for humpback whales and F10 (10 kHz) for dolphins, were used on sharks nets within the Queensland Shark Control Program. Sound from the acoustic pingers was present for around 1.5 km beyond the nets. Humpback whales and dugons were able to hear the F3 pinger 90 m from the net and its two harmonic overtones (5.4 and 8.1 kHz) 10 and 210 m from the net respectively. The F10 pinger was audible to both species up to 130 m from the net. Dolphins could hear the F3 pinger 45 m from the net and it's two overtones 10 and 110 m from the net. The F10 pinger could be detected by dolphins up to 40 m from the net. Shark nets are currently fitted with 3 to 4 pingers per 200 m length of net and therefore appear to be adequate for detection by marine mammals swimming straight at the net and at a top speed. Dolphins heard the F3 pinger 45 m from the net, they could only detect the F10 pinger less than 40 m from the net |
Queensland, Australia |
Gillnets
|
Sharks |
Acoustic deterrent devices
|
Sirenians | Field study in the wild | Acoustic pingers, Fumunda F3 (2.7 kHz) for humpback whales and F10 (10 kHz) for dolphins, were used on sharks nets within the Queensland Shark Control Program. Sound from the acoustic pingers was present for around 1.5 km beyond the nets. Humpback whales and dugons were able to hear the F3 pinger 90 m from the net and its two harmonic overtones (5.4 and 8.1 kHz) 10 and 210 m from the net respectively. The F10 pinger was audible to both species up to 130 m from the net. Dolphins could hear the F3 pinger 45 m from the net and it's two overtones 10 and 110 m from the net. The F10 pinger could be detected by dolphins up to 40 m from the net. Shark nets are currently fitted with 3 to 4 pingers per 200 m length of net and therefore appear to be adequate for detection by marine mammals swimming straight at the net and at a top speed. Dugons heard the F3 pinger 90 m from the net, they heard the F10 pinger up to 130 m from the net |
North Carolina |
Gillnets
|
Spanish mackerel |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | A study was conduceted to test the effect of SaveWave acoustic deterrent devices on target fish catch and bottlenose dolphins in the North Carolina Spanish mackerel gillnet fishery. Observations were carried out on commercial vessels and focal visual and acoustic follows of dolphins were conducted. Fish catches were significantly lower when dolphins were observed interacting with gillnets. The SaveWave device did not affect fish catch. Dolphins were less likely to interact with gillnets and more likely to echolocate when SaveWaves were present. However, SaveWave devices were not sufficiently durable to be deployed in this fishery. Dolphins were less likely to interact with gillnets and more likely to echolocate |
North Sea |
Gillnets
|
Hake |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | Experiments were carried out aboard vessels in the Danish North Sea hake gillnet fishery to determine if increasing the spacing of Aqutec AQUAmark100 pingers could be done without negatively impacting the effectiveness of the pinger. Control nets without pingers were tested alongside nets with pingers spaced at 455 m and 585 m. The control nets had a bycatch frequency of 0.54 incidents/haul for harbour porpoises. Nets with pingers spaced at 455 m had an incidence rate of 0 and nets with pingers spaced at 585 m had a bycatch frequency rate of 0.12. Bycatch indences were significantly different between the control and two experimental groups. This suggests that the spacing of pingers may be increased without significantly impacting their ability to reduce bycatch of harbour porpoises. Pingers spaced at 455 m had 0 bycatch; pingers spaced at 585 m had a bycatch rate of 0.12 |
Queensland, Australia |
Non-specific
|
None |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | Fumunda acoustic alarms were tested in the absence of nets to determine their ability to modify the behavior of Australian snubfin and humpback dolphins, with possible applications to gillnet fisheries. The alarms emitted a regular interval pulse of 300 ms every 4 seconds at 10 kHz frequency. The behavior of the animals changed slightly when the alarms were used but the likelihood of them leaving the area was not significantly different from the control. This suggests this type of acoustic alarm may not be useful as a bycatch mitigation measure for these species. No significant effect on Australian snubfin and humpback dolphins |