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ISSF 2016-17: Mitigation of Silky Shark Bycatch in Tropical Tuna Purse Seine Fisheries
|Date added||December 9, 2016|
|Category||Technical and Meeting Reports, Technical Reports|
|Tags||Bycatch Mitigation, Moreno, Purse Seine, Restrepo, Sharks, Tuna|
|Author(s)||Victor Restrepo, Laurent Dagorn & Gala Moreno|
Pelagic sharks are not targeted by tropical tuna purse seine fisheries, but they are caught incidentally, especially around floating objects like FADs. The shark bycatch-to-tuna catch ratio in purse seine fisheries is quite small, on average, less than 0.5% in weight. Over 90% of that bycatch is composed of silky sharks, Carcharhinus falciformis. Because of their low reproductive rates and other life history characteristics, silky sharks are a vulnerable species.
The contribution of purse seining to the total catch of this species varies by ocean: from 4% in the Indian and Eastern Pacific Oceans, to about 25% in the Western and Central Pacific Ocean regions. The global magnitude of catch of the purse seine fishery is quite large, so reducing the mortality caused by these fisheries can contribute to global conservation efforts. This document summarizes mitigation techniques that can be used in this fishery.