The focus of this study was to compare two selective devices in a trawl by automated counting of fish escapements through each selective device (a white and black square mesh panel) based on video sequencing and an algorithm for automated object detection and tracking. The software detected a significant difference in fish escapement rate according […]
December 2023
Articles | Consortium for Wildlife Bycatch Reduction
Broadhurst, M.K., Millar, R.B., Uhlmann, S.S., Using a double codend to reduce discard mortality, ICES Journal of Marine Science , v. 66, 2009 , ps 2077-2081 Broadhurst, M.K., Smith, T.M., Millar, R.B., Hughes, B., Raoult, V., and Gaston, T.F., Cumulative selectivity benefits of increasing mesh size and using escape gaps in Australian Portunus armatus traps, […]
Shorter trawls improve size selection of northern shrimp | Consortium for Wildlife Bycatch Reduction
The selectivity of the Skagerrak standard trawls were compared with a trawl differing only in the belly length, being 37% shorter. The trawls fished shrimp above 19 mm carapace length equally, while catch rates of shrimp below 15.5–16 mm carapace length in the shorter trawl were more than halved. Bycatch of Norway pout (Trispterus esmarkii) was […]
Optimizing mesh size with escape gaps in a dual-species portunid-trap fishery | Consortium for Wildlife Bycatch Reduction
In south-eastern Australia, baited, round traps (comprising 50–57-mm mesh netting) are used to target giant mud crabs (Scylla serrata) and blue swimmer crabs (Portunus armatus) in spatially separated fisheries. Two experiments assessed the utility of (1) traps partially or completely covered in larger mesh (91 mm to match the minimum legal size of the smaller P. armatus), and (2) […]
Potential limits to anthropogenic mortality of small cetaceans in coastal waters of British Columbia | Consortium for Wildlife Bycatch Reduction
Small cetaceans are by-caught in salmon gillnet fisheries in British Columbia (BC) waters. In Canada, there is currently no generic calculation to identify when management action is necessary to reduce cetacean bycatch below sustainable limits. We estimated potential anthropogenic mortality limits for harbour (Phocoena phocoena) and Dall’s (Phocoenoides dalli) porpoises and Pacific white-sided dolphins (Lagenorhynchus […]
Mitigating bycatch and depredation of marine mammals in longline fisheries | Consortium for Wildlife Bycatch Reduction
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 […]
Behavioral responses of bottlenose dolphins, Tursiops truncatus, to gillnets and acoustic alarms | Consortium for Wildlife Bycatch Reduction
The authors tested the behavioural response of bottlenose dolphins (Tursiops truncatus) to gill nets equipped with active and control Dukane NetMark 1000 pingers. Although dolphins were observed significantly fewer times within a 100m circular buffer zone from the alarms, overall results showed no significant differences in the number of groups observed, or closest approaches by […]
A risk-based approach to rapidly screen vulnerability of cetaceans to impacts from fisheries bycatch | Consortium for Wildlife Bycatch Reduction
Potential risk of fisheries to cetaceans was assessed using a screening procedure based on a Productivity Susceptibility Analysis (PSA) using gears found in Ireland. Gillnets targeting demersal species was assessed as the fishery posing the greatest risk to cetaceans. Pelagic trawls targeting small pelagic species was found to pose a moderate risk to cetaceans. Specific […]
Post-release survival, vertical movements and thermal niche partitioning in five species pelagic sharks released from longline fishing gear in the central Pacific Ocean | Consortium for Wildlife Bycatch Reduction
From 2001 to 2006, 71 pop-up satellite archival tags (PSATs) were deployed on five species of pelagic shark (blue shark [Prionace glauca]; shortfin mako [Isurus oxyrinchus]; silky shark [Carcharhinus falciformis]; oceanic whitetip shark [C. longimanus]; and bigeye thresher [Alopias superciliosus]) in the central Pacific Ocean to determine species-specific movement patterns and survival rates after release […]
Health of North Atlantic right whales Eubalaena glacialis over three decades: from individual health to demographic and population health trends | Consortium for Wildlife Bycatch Reduction
Photographic data on body and skin condition, blowhole cyamids and rake marks were used to evaluate the health of North Atlantic right whales (Eubalaena glacialis) from 1980-2008. A hierarchical Bayesian model was applied to the data to estimate demographic groups, underlying health status conditions and the population to characterize health patterns and temporal trends. Visual […]
Hector's dolphin risk assessments: old and new analyses show consistent results | Consortium for Wildlife Bycatch Reduction
Information on bycatch of Hector’s dolphins in New Zealand waters was reviewed and new estimates were presented. Prior to 2008, 110-150 Hector’s dolphins were estimated to be caught annually. Of these, 35-46 were caught of the east coast South Island. Between May 2009 and April 2010, an estimated 23 Hector’s dolphins were caught of the […]
Interaction between bottlenose dolphin (Tursiops truncatus) and trammel nets in the Archipelago de La Maddalena, Italy | Consortium for Wildlife Bycatch Reduction
A study was conducted in the waters off the coast of Archipelago de La Maddalena (Italy) to determine the impact bottlenose dolphins had on gillnet fisheries targeting a variety of fish species. The study showed that the catch per unit effort of target species was significantly higher when there were no dolphin interactions. There were […]
Review and evaluation of three mitigation measures-bird-scaring line, underwater setting and line shooter-to reduce seabird bycatch in the north Atlantic longline fishery | Consortium for Wildlife Bycatch Reduction
Bird-scaring lines, underwater setting and line shooters all reduced the incidental capture of seabirds, with bird-scaring lines being the most effective. These mitigation measures also reduced bait loss and increased the catch rates of target species.
The effects of neodymium-iron-boron permanent magnets on the behavior of the small spotted catshark (Scyliorhinus canicula) and the thornback skate (Raja clavata) | Consortium for Wildlife Bycatch Reduction
Neodymium-iron-boron (Nd2Fe14B) permanent magnets were used to test behavioral responses in spotted catsharks (Scyliorhinus canicula) and thornback skates (Raja clavata). Both species significantly avoided the Nd2Fe14B magnets more often in comparison to the control and procedural control and they fed significantly more from the control an procedural control in comparison to the magnets. The study also […]