Search The Database

The authors used onboard observers and fishing records to evaluate marine mammal bycatch in trawl fisheries of the San Matías Gulf, Argentina. Results show that of 46 incidentally caught species, the American sea lion (Otaria byronia) was caught most frequently, and that catch was associated with proximity to colonies and the target species identity. Significantly higher bycatch rates were observed in the hake (Merluccius hubbsi) fleet.

The authors evaluated factors influencing marine mammal bycatch in static net fishing operations in the UK between 1996 and 2023. Since 2014, harbour porpoise (Phocoena phocoena)  bycatch has been decreasing while common dolphin (Delphinus delphis) bycatch has been increasing; grey seal (Halichoerus grypus) and harbour seal  (Phoca vitulina) bycatch has been increasing gradually across the time period. Influential factors included seasonal patterns, water depth, and level of fishing effort. 

Seal exclusion devices (SEDs) are effective in reducing pinniped bycatch in the Patagonian squid fishery, however, drowning may still occur during trawl hauling. 

An analysis of records of static net bycatch sampling in the United Kingdom from 1996-2023 found that use of acoustic deterrent devices (ADDs) reduced harbor porpoise (Phocoena phocoena) bycatch per haul (BpH) to 0.23 of the background rate. BpH increased for harbor seals and grey seals (Phoca vitulina and Halichoerus gryphus) when ADDs were used. Current efforts to reduce harbor porpoise bycatch may be increasing seal mortality in the same fisheries. 

Several designs of seal exclusion devices (SEDs) were tested to reduce bycatch of Australian fur seals (Arctocephalus pusillus doriferus) in the winter blue grenadier (Macruronus novaezelandiae) trawl fishery. A 'top-hatch' SED, or one with a top-mounted escape hatch, resulted in the lowest occurrence of seal bycatch than any other SED design or than nets without a SED. The SED prevented entry into the net codend where drownings occurred. SEDs also successfully expelled seals and limited access into the net via the escape hatch. Cameras are needed to verify the results.