Search The Database
Location | Gear | Catch | Technique | Bycatch species | Type | Results |
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Cape Solander, Sydney Australia |
N/A |
Acoustic deterrent devices
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Megaptera novaeangliae (Humpback whale) | Field study in the wild | The ability of acoustic alarms to alert migrating humpback whales (Megaptera novaeangliae) to fishing gear was tested. Two alarms were used, each with a distinct tone. One alarm had a 5 kHz tone (5 s emission interval and 400 ms emission duration), and one had a 2-2.1 kHz swept tone (8 s emission interval and 1.5 s emission duration). The response of the whales in terms of changes to surface behavior and travel direction were investigated. A total of 108 migration tracks were collected using a theodolite. The study was conducted at Cape Solander, Sydney, Australia. The whales showed no detectable response to either of the alarms; direction and surfacing behavior did not vary between when the alarms were on or off. These types of tones are unlikely to be effective as whale entanglement deterrents. There were no differences in behavior of migrating whales when alarms were on or off |
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Hooks-and-Lines
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Acoustic deterrent devices
Time area closures
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Mammals | Summary study | This study provides a summary of methods that can be used to reduce depredation and bycatch of marine mammals in longline fisheries. Methods include 1) spatial management methods, 2) acoustic methods, 3) physical methods and 4) 'other methods'. The results indicate that some methods can be used with both pelagic and demersal longlines, while others can be used with only one or the other. In addition to the methods investigated, the results highlight significant knowledge gaps.These include survivability after hooking and entanglement. This lack of information hinders assessing serious injury and mortality to marine mammals after interactions with longline fisheries occur. The development of deterrents would also be improved with increased knowledge of marine mammal behavior near longlines. |
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Western Australia |
Traps
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N/A |
Acoustic deterrent devices
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Megaptera novaeangliae (Humpback whale) | Summary study | The authors investigated several data sources and conducted surveys to identify potential mitigation measures that could be used to reduce humpback whale entanglements in Western Australia (WA). The Cetacean Stranding Database (CSD) and Commercial Whale Watching Database (CWWD), managed by the Western Australia Department of Parks and Wildlife, were both investigated. High occurrences of whale entanglements off the central coast of WA were identified in the CSD. Commercial fishing records combined with entanglement records indicated that entangled whales mostly move contrary to movement patterns of the general population. Suggesting the high entanglement rates off the central coast may be reflective of southern and eastern movements of entangled whales during their northward migration. The CWWD database indicated changes in the timing of whale migrations. Updates to logbooks were also made during this study. Paper based logbooks were updated to smart-phone applications. Spatial models indicated that depth ranges of 4-40 ma nd distance from the coast (5-21 m) are useful in predicting the occurrence of humpback whales. An industry lead workshop identified potential whale entanglement mitigation measures, all of which were trialed by fishers after the workshop. All mitigation measures tested, except for remote releases, showed a trade off between price and practicality. Based on these results, rope type, rope length and number of floats used were tested industry wide during trials. This project examined the use of acoustic pingers and found their use made no difference to the behavior of humpback whales. An assessment of their effectiveness was not conducted during this study. Other results from this study indicated, preliminarily, that whales are more likely to become entangled in thinner ropes, and mainlines that are yellow or orange. Preliminary results suggest pingers made no difference to Humpback whale behavior |
Queensland, Australia |
Gillnets
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Shark |
Acoustic deterrent devices
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Megaptera novaeangliae (Humpback whale), Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | Pingers have been used on shark nets set along Queensland's beaches since 1992. Due to an increase in whale entanglements in 2009, new pingers (Fumunda F3 whale pingers and F10 dolphin pingers) were deployed between July and August 2010. Subsequently updated research on the use of these pingers was needed. For this study, the acoustic characteristics of pingers used on shark nets in Queensland Australia were measured and used to model sound propagation, estimate over what range marine mammals could detect the pingers, monitor ambient noise and to make recommendations on pinger deployment to the Queensland Shark Control Program (QSCP). The results of the sound propagation study indicate that the tones were a few hundred Hz less (2.6-2.8 Hz for F3 and 9.4-9.6 Hz for F10) than indicated. All pingers emitted multiple harmonics and fundamental tones. The power spectrum density levels varied up to 20 dB from angle to angle and pinger to pinger. The 1st harmonic of F3s was audible to all marine mammals over the longest ranges. Only 2 of the 6 tested pingers reached the manufacturer's listed audible range of 1-5 km. During testing, the ranges depended on the individual pinger and angle of the pinger toward the mammal. When animals travel alongside the net, a number of pingers should be set in a series. Based on the current configuration of 3-4 pingers per net of 200 m, humpback whales would hear all of the pingers at any location along the net but dolphins would hear only 1-2 pingers. When animals swim straight at the net, maximum pinger spacing would need to be based on the animals swim speed. The current net/pinger configuration is adequate for humpback whales, dugongs and dolphins swimming at normal travelling speeds. The current pinger spacing is insufficient for dolphins swimming straight at the net at high speeds. The current net/pinger configuration is adequate for humpback whales, dugongs and dolphins swimming at normal travelling speeds. The current pinger spacing is insufficient for dolphins swimming straight at the net at high speeds. |
Gillnets
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N/A |
Acoustic deterrent devices
Passive acoustic deterrents
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Large Cetaceans (maximum length > 7.5 meters), Small Cetaceans (maximum length < 7.5 meters) | Summary study | A summary study of methods used to reduce or eliminate marine mammal entanglements was conducted. The authors found little evidence on the effectiveness of the use of sound to reduce or eliminate marine mammal incidental capture. Substantial decreases in cetacean bycatch, due to the use of passive methods such as increasing fishing net reflectivity, were not evident through comparisons of catch rates in commercial fisheries or from observational deterrence studies. Net alarms have been shown to greatly reduce whale entrapment in Canadian fish traps but similar success has not been shown in reducing small cetacean bycatch in many gillnet fisheries. Few controlled studies on the use of sound to reduce or eliminate marine mammal interactions have been conducted. There is a need to additional basic research on echolocation behavior and behavioral interactions between marine mammals and fisheries. Net alarms do not appear ver effective in reducing small cetacean entanglements in gillnets |
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Australia |
N/A |
Acoustic deterrent devices
Passive acoustic deterrents
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Megaptera novaeangliae (Humpback whale) | Field study in the wild | A study was conducted with humpback whales to test their response to recordings of conspecific social sounds and an artificially generated tone stimulus. Experiments were conducted during humpback whales southward migration along the east coast of Australia. A total of 13 tone experiments, 15 social sound experiments and 3 silent controls were conducted during two field seasons (September/October 2004 and 2008). The results indicated that humpback whales respond differently, with respect to course traveled and dive strategy, to the two stimuli. Humpback whales responded to 'tones' by moving offshore and surfacing more often, perhaps trying to avoid the stimuli. These changes were related to the proximity to the source, the received signal level and signal to signal noise ratio. When social sounds were used the responses were very variable and dependent on the groups composition. This study indicates that behavioral responses of marine mammals to acoustic stimuli is complex and in need of additional research. Humpback whales responded to 'tones' by moving offshore and surfacing more often, perhaps trying to avoid the stimuli. Responses to social sounds were more variable. |
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Bay of Fundy |
na |
Acoustic deterrent devices
Passive acoustic deterrents
Vessel noise reductions
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Eubalaena glacialis (NA Right whale) | Field study in the wild | Risk factors involving ship strikes and North Atlantic right whales were investigated in this study. A multi-sensor digital acoustic recording tag (DTAG) was used to measure the responses of whales to four stimuli: vessel noise, social sounds of conspecifics, and a signal designed to alert whales. Silence was used as the control measure. Testing was conducted in the Bay of Fundy summer foraging region. The DTAGs are non-invasively deployed and record all sounds at a sampling rate of 32 kHz, a Nyquist rate of 16 kHz and records the pitch, roll, heading and depth of the whale at a sampling rate of 46 Hz. Whales showed a strong reaction to the alert signal, swimming strongly to the surface. Whales showed a mild response to social sounds and no response to sounds of an approaching vessel. The response to the alert signal would more likely result in an increased risk of collision and not a decreased risk. Whales showed a strong response to alert signals. |
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Cornwall |
Gillnets
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Hake |
Acoustic deterrent devices
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Small Cetaceans (maximum length < 7.5 meters) | Summary study | Four commercially available pingers (AIRMAR, Aquamark 100, Fumunda, Save Wave Saver) were tested on vessels operating in Cornwall targeting hake with gillnets. Pingers were tested for their effectiveness at reducing incidental interactions between the gillnets and porpoises. Only one of the four tested pingers, AIRMAR, performed 'satisfactorily'. Only the AIRMAR pinger worked satisfactorily |
Omura Bay, Japan |
Gillnets
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Not studied |
Acoustic deterrent devices
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Neophocoena spp. (finless porpoise) | Field study in the wild | A long-term study assessed the efficiency of acoustic pingers (AQUAmark 100, 20-160kHz) in reducing the encounter rates of finless porpoises (Neophocaena spp.) with fishing nets. The study used a passive recorder to obtain acoustic encounter rates of echolocating finless porpoises over two eight-month periods. Encounter rates were significantly lower in periods when pingers were in use, but this effect decreased over time. By the end of each study period, the number of encounters was greater than those during periods without pingers, suggesting that habituation had occurred. However, when pingers were reactivated after four months of no use, encounters returned to lower levels, such as those observed during the beginning of the experiment. The results suggest that habituation to pingers may be mitigated by alternating periods of silence with periods of active pinger use. Initially, pinger use decreased porpoise encounter rates with gillnets. However, this effect decreased over time but was effective later after temporary cessation of pinger use. |
northern Cyprus |
Gillnets
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Bony fish |
Acoustic deterrent devices
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Small Cetaceans (maximum length < 7.5 meters) | Field study in the wild | The study combined fisher questionnaires, acoustic monitoring, and participatory experiments to investigate the occurrence of bottlenose dolphins (Tursiops truncates) in the gillnet fisheries of Northern Cyprus. Dolphins were present in fishing grounds throughout the year, and were detected at 28% of net sets. Net damage was six times greater when dolphins were present during sets. Use of an acoustic pinger (AQUAmark 200, 5-160kHz) was tested, but had no significant effect on dolphin presence. |