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Factors Influencing Bycatch Mortality of Trawl‐Caught Pacific Halibut
Author(s) -
Richards Laura J.,
Fargo Jeff,
Schnute Jon T.
Publication year - 1995
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1995)015<0266:fibmot>2.3.co;2
Subject(s) - halibut , bycatch , fishery , fishing , fish <actinopterygii> , trawling , hippoglossus hippoglossus , environmental science , geography , biology
Retention of Pacific halibut Hippoglossus stenolepis has been prohibited in U.S. and Canadian trawl fisheries since 1944, and all trawl‐caught halibut must be released. Halibut bycatch mortality has increased over the last decade in the British Columbia trawl fishery, sparking renewed interest in the factors influencing bycatch mortality. In 1970 and 1992, observers on trawl vessels assessed the physical condition of Pacific halibut caught and released. In an earlier paper, we related the physical condition of halibut from the 1992 study to the time each halibut spent on the vessel deck, halibut length, total weight of the catch, tow depth, and tow duration. Here, we extend our analysis to physical condition data from the 1970 study. using survival estimates from a mark–recapture experiment to interpret the results directly. We show that all measured factors influence the survival of discarded Pacific halibut. Significant reductions in bycatch mortality could be achieved with shorter handling times. Survival was higher in the 1992 study for given halibut lengths, handling times, and fishery characteristics, but measured factors could not account for the difference from survival in 1970. Further experiments arc required to confirm estimated relationships between Pacific halibut physical condition and survival or mortality after trawl capture and release.