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Survival of Atlantic cod (Gadus morhua) in the northwest Atlantic longline fishery
Milliken, H.O.; Farrington, M.; Carr, H.A.; Lent, E. (1999). Survival of Atlantic cod (Gadus morhua) in the northwest Atlantic longline fishery. Mar. Technol. Soc. J. 33(2): 19-24
In: Marine Technology Society Journal. Marine Technology Society (MTS): Washington, D.C.. ISSN 0025-3324, more
Peer reviewed article  

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  • Milliken, H.O.
  • Farrington, M.
  • Carr, H.A.
  • Lent, E.

    Longline fishing has often been promoted as a clean, low impact fishing method.Some longline fishermen and biologists have expressed concern that there is a highmortality rate for cod and haddock that pass through a dehooking device prior torelease. The device, aptly called the "crucifier," usually consists of two steel cylindersplaced vertically on the gunwale of the vessel. During hauling, the gear passesthrough the opening between the cylinders while the fish, too large to pass throughthe narrow opening, is excluded. This process pulls the hook from the mouth of the fish and can inflict severe injuries such as torn and broken jaws. A study wasconducted to determine the survival rate of sub-legal cod caught in the longlinefishery using 11/0 circle hooks. The focus of the research was to assess the rate ofmortality of sub-legal catch after the cod were placed in cages for 72 hours. Theresults of the study showed that there was high mortality (69%) associated withcapture using the 11/0 circle hook when the fish were injured by the process ofhaving the hooks removed from their mouths by the crucifier. Furthermore, sublegalcod that had wounds from the dehooking process and were under 39 cm werestatistically more likely to die as compared to cod between 38 and 49 cm. Anancillary set of observations on the predation by sea birds of released sublegal codwas included. Despite low numbers, the findings from these observations show thatsea bird predation should be included when estimating the survival of fish caught by alongline.

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