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Location | Gear | Catch | Technique | Bycatch species | Type | Results |
---|---|---|---|---|---|---|
Baltic sea |
Traps
|
Salmon |
Acoustic deterrent devices
|
Pinnipeds | Field study in the wild | AHDs with a source level of 179 dB re 1 µPa rms at 1 m were deployed during three consecutive fishing seasons. Fish catches in traps with AHDs were significantly higher than in the controls, while catch damage in the traps with AHDs was lower. However, towards the end of the fishing season catch damage increased in traps with AHDs. Reduced depredation of salmon traps by grey seals (Halichoerus grypus) |
Balearic Islands, Mediterranean Sea |
Gillnets
|
Mixed species |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | A large scale pinger trial was conducted and results showed a 49% decrease dolphin depredation rates when pingers were active. However the different pinger brands tried were not equally effective in reducing depredation. The AQUAmark 210 pingers had significant results, while Dukane Netmark 1000 and SaveWave Dolphinsaver High-impact did not have significant results. Profit per unit increased 9%. 49% reduction in depredation rate by bottlenose dolphins (Tursiops truncatus) |
Mediterranean, Balearic Islands |
Gillnets
|
Red mullet |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | The experiment tested the effects of Aquamark 100 pingers on the depredation rate of bottlenose dolphins on trammel nets. Results showed nets equipped with pingers had 87% fewer holes (attributed to damage by dolphins) than nets without pingers. Reduced bottlenose dolphin (Tursiops truncatus) depredation |
North Carolina, USA |
Gillnets
|
Mixed |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | No difference on group size or closest approach to the net between active and control pingers |
Turkey |
Gillnets
|
turbot fish |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | Reduced harbor porpoise interactions with gillnet |
Akaroa Harbour, New Zealand |
Gillnets
|
None reported |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | White Dukane pingers with a fundamental frequency of 10kHz and harmonies of up to 160 kHz, elicited the strongest response from Hector's dolphins, compared to the black Pice and red Dukane pingers. More than half (62.5%) of the dolphins exhibited avoidance when exposed to the white pinger. However, no significant differences between pingers were found in the rate of echolocation clicks per dolphin or dolphin group, or among the peak frequencies of subset clicks. 62.5% of individuals elicited avoidance behavior (using white Dukane pingers) |
North Sea |
Gillnets
|
Cod |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | 100% reduction in harbor porpoise bycatch |
North Sea |
Gillnets
|
Cod |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | Bottom set gillnets with pingers (LU-1, 8 signals, 145 dB, 300 ms, random signal intervals) attached were tested against standard nets and nets with dummy pingers (double blind) to determine if they could reduce the incidental capture of harbour porpoises. The proportion (number of nets with porpoises/number without) of harbour porpoise bycatch was reduced from 0.00229 and 0.00295 for nets with dummy pingers and no pingers respectively, to 0.00015 for nets with active pingers. The difference in bycatch rates between nets with active and dummy pingers was statistically significant but not between nets with dummy pingers and with no pingers. Reduced catch rates from 0.00229 and 0.00295 for nets with dummy pingers and no pingers respectively, to 0.00015 for nets with active pingers |
Baltic |
Gillnets
|
None reported |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | Pingers significantly reduced echolocation encounter rates by 50-100% at 500m; sighting reduced up to 375m. Porpoise return time was 6 hrs when pingers were silent after being active for 24 hrs 50 min |
Sardinia, Italy |
fin-fish farm |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | Acoustic harassment devices (AHDs) were tested in association with a marine fin-fish farm off the north-eastern coast of Sardinia, to determine their effectiveness on common bottlenose dolphins. This was a controlled exposure experiment. No significant or immediate effects on bottlenose dolphin presence, distance from AHD, group size or time spent in the fish farm area were caused by activation of the AHD. Thus, additional research is needed on their effectiveness in the marine environment before further deployment. |