Search the Database
Location | Gear | Catch | Technique | Bycatch Species | Type | |
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global |
Hooks-and-Lines | Teleosts | Alternative leader design, Circle hooks, Electromagnetic deterrents, Raised demersal longlines | Elasmobranchs | Summary study | |
Summary: A meta-analysis of online publications revealed only one technique to be effective as a bycatch reduction device in longline fisheries, which involves raising demersal longlines off the seafloor using flotation. Other techniques as BRDs include monofilament leaders which, like floating demersal longlines, are suggested as promising approaches for further evaluation. Although not effective as a deterrent, circle hooks may increase survivaility post-hooking. Effect on Bycatch: |
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Western Mediterranean (Spain) |
Trawls | Caretta caretta (Loggerhead turtle) | Summary study | |||
Summary: A questionaire administered to the bottom trawling fleet in the western Mediterranean (northeastern Spain) reported 238 bycacth events involving loggerhead sea turtles (Caretta caretta), calculated as a monthly CPUE of .09. The authors dicuss this figure relative to nearby coastal regions and suggest some possible mitigation measures. Effect on Bycatch: |
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Hawaii, USA |
Hooks-and-Lines | Bigeye tuna (Thunnus obesus) | Pseudorca crassidens (False killer whale) | Summary study | ||
Summary: This study examined spatial interactions between false killer whales (Pseudorca crassidens) and the Hawaii-based deep-set longline fishery. False killer whales occur as bycatch in this fishery that exceed allowable levels. Five satellite tagged whales (occurring within three groups) in combination with logbook entries showed that only two groups of whales approximated gear at a distance closer than 50km. On two occasions whales from one group came close enough to interact with gear, and one of six sets involved had no catch which may be explained by depredation. The haul phase showed the highest “attraction effect,” and the results suggest this portion of fishing activity may be an important factor in bycatch, especially seeing as at other times the whales showed limited time interacting with gear. Effect on Bycatch: N/A |
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North Coast, Australia |
Trawls | Prawns: White Banana (Fenneropenaeus merguiensis), Red-legged Banana (F. indicus), Brown Tiger (Penaeus esculentus), Grooved Tiger (P. semisulcatus), Blue Endeavour (Metapenaeus endeavouri), and Red Endeavour (M. ensis) | Excluder devices | Invertebrates | Field study in the wild | |
Summary: In 2015, NPF Industry Pty Ltd launched the Northern Prawn Fishery’s Bycatch Strategy 2015-2018 with the vision to reduce small bycatch by 30% in three years. A key component of the strategy was industry innovation and through this process the Kon’s Covered Fisheyes Bycatch Reduction Device (BRD) was developed.In 2016, at-sea testing of the Kon’s Covered Fisheyes Bycatch Reduction Device (BRD) was conducted in the Gulf of Carpentaria to determine its effectiveness in reducing small bycatch in the tiger prawn fishery compared to a currently legislated device. The device was found to significantly reduce small bycatch by approximately 36.7%, with commercial prawn catch increasing by an average of 0.5%. The device proved to be easy and safe for crew to use and due to the significant reduction in bycatch, the time taken for crew to process the catch was reduced. Effect on Bycatch: Reduced bycatch if small individuals by 37.6% |
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Traps | Lobster, crab, whelk, hagfish | Weak links/ropes | Eubalaena glacialis (NA Right whale) | Study in the lab | ||
Summary: A computer model was produced to provide insight into how the Critically Endangered North Atlantic right whale (NARW) becomes entangled. It allows an anatomically accurate model of a NARW Population estimates of the critically endangered North Atlantic right whale to "swim" into fishing pot ropes, that incorporate realistic physical properties and can generate measures of physical forces (such as rope tension). Modeled entanglement events showed that those involving the pectoral flippers with body wraps were more easily generated than entanglements involving the tailstock only. The simulator is intended as a tool for testing potential new gear configurations. Effect on Bycatch: N/A |
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Melbourne Zoo, Australia |
Gillnets | N/A | Visual deterrents | Eudyptula minor (Little penguin) | Study in the lab | |
Summary: The ability of little penguins (Eudyptula minor) to distinguish differently colored netting materials was tested under controlled conditions to test gillnet color as a potential bycatch mitigation technique. Clear, green, and orange colored monofilament were tested in the form of a gillnet mimic in an enclosed tank containing 25 penguins. Orange colored monofilament line resulted in lower collision rates with the gillnet mimic (5.5%) in comparison with clear (35.9%) and green (30.8%) monofilament lines. Further testing under experimental conditions, accompanied by at-sea trials to verify effectiveness in varied light conditions is needed, as well as an assessment of the effect of gillnet color on the catch efficiency of target species. Effect on Bycatch: Orange colored monofilament resulted in lower collision rates with a gillnet mimic versus green and clear monofilament |
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U.S. West Coast |
Hooks-and-Lines | Sablefish (Anoplopoma fimbria) | Bird-scaring devices, Night sets | Phoebastria nigripes (Black-footed albatross) | Field study in the wild | |
Summary: The study assessed the efficacy of applying bird scaring line regulations from the demersal longline fishery in Alaska to a similar fishery along the U.S. West Coast. However, unlike in the Alaskan sablefish fishery, some U.S. West Coast sablefish vessels utilize floated longlines. Results from the study confirmed that bird scaring regulations from Alaska were sufficient to protect baits from bird attacks on longlines without floats, but not baits with floats. One reason for this pattern might be that floated longlines sink more slowly, meaning that the lines are typically beyond the protection of the bird scaring lines before they sink below the reach of seabirds such as albatrosses. The analysis also confirmed testimonials from fishermen that night setting reduced albatross bycatch by an order of magnitude compared to daytime setting, without reducing target catch. The use of night setting may be an effective albatross bycatch prevention practice for the West Coast sablefish fishery, and provides an alternative to bird scaring lines for vessels using floated longlines. Effect on Bycatch: Albatross attacked baited hooks on floated longlines at significantly higher rates than non-floated longlines, especially beyond the aerial extent of bird scaring lines. Additionally, night setting resulted in significant decreases in albatross bycatch. |
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Southeastern Australia |
Traps | Blue swimmer crab (P. armatus) | Trap-net modification | Bony Fishes, Invertebrates | Field study in the wild | |
Summary: The individual and cumulative effects of increasing mesh size and installing three escape gaps (36 × 120 mm) in collapsible‐netted round traps were assessed to address concerns associated with excessive discarding in an Australian portunid fishery. Compared to conventional traps of 56‐mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 54%) undersized blue swimmer crabs, Portunus armatus, and yellowfin bream, Acanthopagrus australis (by 64%). Irrespective of escape gaps, simply increasing the mesh size to 75 mm did not significantly affect catches of undersized P. armatus, although 87% fewer A. australis were retained. Traps with both 75‐mm mesh and escape gaps maintained reductions of A. australis, but had a clear cumulative effect on P. armatus selection, retaining 84% fewer undersized individuals across a larger size at retention. The results support using escape gaps in existing conventional traps, but illustrate the need to configure the minimum legal mesh size to approach the desired target size of P. armatus as a precursor to maximizing trap selectivity. Effect on Bycatch: 87% reduction in yellowfin bream, 84% reduction in undersized crab |
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Southeastern Australia |
Traps | Blue swimmer crab (P. pelagicus) | Trap-net modification | Invertebrates | Field study in the wild | |
Summary: Data was collected on the relative performance of single and multiple round, rectangular, and square escape gaps across three fishing operations. Compared to control traps, those with escape gaps maintained catches of legal-sized P. pelagicus, but caught 51–100% fewer undersized individuals. Generally, rectangular escape gaps and especially multiple configurations were the most effective. Escape gaps represent a low-cost option for minimizing interactions with unwanted catches throughout the fishery. Effect on Bycatch: 51-100% reduction of juvenile crab |
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Florida, USA |
Traps | Stone crab (Menippe mercenaria) | Trap-net modification | Bony Fishes, Stone crab (Menippe. mercenaria) | Field study in the wild | |
Summary: The experiment aimed to determine what size of cull ring would reduce the catch of pre-recruit stone crab (Menippe mercenaria) and other bycatch while maintaining legal-sized catch. Catch compositions of crabs from unmodified plastic commercial stone crab traps and traps fitted with three sizes of cull rings were compared in the stone crab fishery across Florida’s west coast. Traps outfitted with cull rings retained bigger crabs, had less bycatch, and fewer pre-recruit crabs, while yielding the same number of legal-sized crabs as traps without cull rings. A 55.6 mm cull ring was then distributed to commercial fishermen, who reported anecdotally that they liked the performance of the rings and felt that it would improve the efficiency of their operations. Effect on Bycatch: Decreased catch of bycatch species and pre-recruit stone crabs |
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