Science Advisory Report  2011/057

Considerations for the Estimation of Incidental Catch in the Eastern Canadian Swordfish/Other Tunas Longline Fishery

Summary

• The existing Observer Program provides critical information on the catch composition of the swordfish/other tunas (yellowfin tuna, bigeye tuna and albacore) longline fishery. This information is currently used for estimating bycatch and discards. The Regional Advisory Process (RAP) confirmed the utility of this information but concluded that various modifications are required to improve the quality of the advice.
• The eastern Canadian swordfish/other tunas longline fishery is in a period of reduced effort that began in 2007 (although landings have not declined).
• Under the existing target at-sea Observer deployment scheme, fishing trips should have roughly an equal probability of being selected to carry an at-sea Observer. Analyses presented at the RAP indicated that this is not the case.
• It was recommended at the RAP that there be a separate process to evaluate dead discard estimation methods for bluefin tuna, swordfish, shortfin mako, porbeagle and blue shark.
• A review of available methods for assessing post-release mortality was completed. Of the currently available methods, it was concluded that the combination of field observations using standardized release codes validated with satellite tags offers the most informative results concerning survival of released incidental catch.
• Among the species considered at this meeting, the highest priorities for studies of post-release mortality were thought to include porbeagle and loggerhead sea turtle.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, regional advisory meeting of July 11-12, 2011, on Considerations for the Estimation of Incidental Catch in the Eastern Canadian Swordfish/Other Tunas Longline Fishery. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

Complete document (PDF, 207 KB)

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