Search The Database
Location | Gear | Catch | Technique | Bycatch species | Type | Results |
---|---|---|---|---|---|---|
Peru |
Gillnets
|
Sharks and rays |
Acoustic deterrent devices
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Small Cetaceans (maximum length < 7.5 meters), Globicephala spp. (Pilot whale) | Field study in the wild | Acoustic pingers (Dukane Netmark 1000; frequency of 10-12 kHz and emit 300 ms tone every 4 sec with a source level range of 120-146 dB) were assessed to determine the effectiveness for reducing bycatch of dolphins and porpoises (common dolphins, dusky dolphins, bottlenose dolphins, Burmeister's porpoise, and pilot whales) by Peruvian small-scale driftnet fleets. Pingers were tested between April 2009 and August 2011. Twenty-two percent of the control nets captured small cetaceans and 16% of experimental nets captured small cetaceans. This was a 37% reduction in bycatch rates, suggesting that pingers may be effective in reducing bycatch of small cetaceans in this fishery. Catch rates of the fishery's target shark and ray species was not changed. |
Neeltje Jans, The Netherlands |
Gillnets
|
n/a |
Acoustic deterrent devices
Passive acoustic deterrents
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Study in the lab | Two porpoises were subjected to 3 different underwater sounds (standard Dukane alarm, random Dukane alarm, and a "bird alarm") in a enclosed floating pen. Their behavior during a 15 min test period was compared to behavior during a baseline 15 min period before the test and a recovery period after the test. All alarms resulted in increases in both the distance of the animals' surfacings from the alarms and their respiration rates. The standard Dukane alarm and the bird alarm were more effective than the random alarm in inducing animals to swim away from the source. Increased distance from the alarm source and respiration |
Denmark |
Gillnets
|
n/a |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Study in the lab | Two captive harbor porpoises were exposed to three sound types (frequency from 100 kHz to 140 kHz, 200 ms long, and presented once per 4 s). Each session consisted of a 10 min period persound, a 5 min period of sound, and a 10 min period after the sound. Behavior was recorded on video and with dataloggers. Animals reacted most to the intial presentations of sound, but the reactinos diminished rapidly in repeated sessions. Initial response that diminished with additional trials |
Bay of Fundy |
n/a |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters), Phocoena phocoena (Harbor porpoise) | Field study in the wild | A field test was conducted to test whether harbor porpoises habitutate to pingers over time. Echolocation and movements were monitored around a mooring equipped with a pinger (Dukane Netmark 1000) for 3 months. Initial displacement was 208 m from the pinger, but it diminished by 50% within 4 days. Echolocation rate and occurrence were significantly reduced near the pinger. Displaced porpoises initially by 208m, but decreased by 50% after four days |
|
Scotland |
Traps
|
Salmon |
Acoustic deterrent devices
|
Pinnipeds | Field study in the wild | An acoustic deterrent device (ADD) was tested at a Scottish salmon double bagnet to deter seals (grey and harbor). The ADD was randomly assigned to be on or off during observations, which were carried out from shore. When the ADD was on, there were significantly fewer seals observed and 1/3 more fish were landed per hour than when the ADD was off. Seal damaged fish were only found when the ADD was off. Significantly reduced seal presence |
Scotland |
Hooks-and-Lines
|
Salmon |
Acoustic deterrent devices
|
Pinnipeds | Field study in the wild | Trials of acoustic deterrent devices (ADD) were carried out on the River North Esk and River Conon in Scotland to test the effectiveness of deterring seals from a specific area of the river and as a barrier to upstream movement of the seals. The ADD was switched on and off alternatively for periods of several days and surveys were carried out to estimate the number of seals present within each river. The ADD had no significant effect on the abundance of seals in the survey area, but it did reduce seal movement upstream significantly. The reduction in movement was constant over the four month period of the trial. Reduced movement upstream significantly (~50%) |
California |
Gillnets
|
Swordfish and thresher shark |
Acoustic deterrent devices
|
Phocoena phocoena (Harbor porpoise), Pinnipeds | Field study in the wild | The long-term effectiveness of acoustic pingers in reducing marine mammal bycatch was assessed in the California swordfish and thresher shark drift gillnet fishery. Bycatch was observed at sea between 1990 and 2009, with acoustic pingers being present from 1996 to 2009. Bycatch rates of cetaceans decreased by around 50% when pingers were present; the decrease was mostly driven by common dolphins. Beaked whales have not been incidentally caught since 1995. Pinger failure occurred in less than 4% of observed sets. Cetacean bycatch was 10 times higher in sets where more than one pinger failed. There was no evidence of habituation to pingers by cetaceans. Bycatch rates of California sea lions was almost double in sets with pingers than without, leading the authors to examine the "dinner bell" effect of pingers. Depredation of swordfish by sea lions was not linked to pinger use, instead the best predictors were total swordfish catch, month and area fished, and nighttime light use. Decreased cetacean bycatch and no habituation. Pinniped bycatch was not significantly different |
Shannon Estuary, Ireland |
Acoustic deterrent devices
|
Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | Change in vocalisation rate in static trials when continuous pingers were active |
||
Oregon |
N/A |
Acoustic deterrent devices
|
Large Cetaceans (maximum length > 7.5 meters) | Field study in the wild | Low-powered sound sources were tested for their ability to deter gray whales from potentially harmful areas. An acoustic device (1-s frequency modulated 1-3 kHz warble deterrent signal) was moored to the seafloor in the gray whales migration path off central Oregon. Observers (land based) tracked whales with a theodolite to locate whales as they passed the headland. Tracklines were compared between times when the acoustic deterrent was on and off. Statistical analysis did not show a significant difference between the hypothesized zone of influence (within 500 m of the deterrent) and areas out to 3 km. Poor weather and equipment issues prevented acquiring an adequate sample size, so the results were considered inconclusive. |
|
Cape Solander, Sydney Australia |
N/A |
Acoustic deterrent devices
|
Megaptera novaeangliae (Humpback whale) | Field study in the wild | Acoustic deterrents were tested for their ability to deter humpback whales (Megaptera novaeangliae) from potential sources of entanglement. Low frequency (3 kHz, 135 +/- 5 db, 5 s emission interval and 400 ms emission duration) alarms were tested. Alarms were placed in the center of the northerly migration path (southern hemisphere) of humpback whales. Observers, who were unaware of the alarm status (i.e. on/off) tracked the pods as they passed the alarms. Sixty percent of the pods (N=137) passed within the assumed detectable range (500 m) of the alarm. Sixty five percent passed the alarm while it was onand 52% when it was off. Therefore, there does not appear to be any noticeable response from the whales to the alarms. There were no differences in the directionality, course heading or dive duration within the detectable range of the alarm, whether on or off. It is therefore unlikely that single alarms currently used with trap or pot lines are effective at reducing interactions with humpback whales. No detectable differences in behavior was found between when alarms turned on or off. |