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Bycatch governance and best practice mitigation technology in global tuna fisheries

Publication - 18 August, 2011
Overexploitation of bycatch and target species in marine capture fisheries is the most widespread and direct driver of change and loss of global marine biodiversity. Bycatch in purse seine and pelagic longline tuna fisheries, the two primary gear types for catching tunas, is a primary mortality source of some populations of seabirds, sea turtles, marine mammals and sharks. Bycatch of juvenile tunas and unmarketable species and sizes of other fish in purse seine fisheries, and juvenile swordfish in longline fisheries, contributes to the overexploitation of some stocks, and is an allocation issue.

There has been
substantial progress in identifying gear technology solutions to seabird and sea turtle bycatch on
longlines and to direct dolphin mortality in purse seines. Given sufficient investment, gear technology
solutions are probably feasible for the remaining bycatch problems. More comprehensive consideration
across species groups is needed to identify conflicts as well as mutual benefits from mitigation
methods. Fishery-specific bycatch assessments are necessary to determine the efficacy, economic
viability, practicality and safety of alternative mitigation methods. While support for gear technology
research and development has generally been strong, political will to achieve broad uptake of best
practices has been lacking. The five Regional Fisheries Management Organizations have achieved mixed
progress mitigating bycatch. Large gaps remain in both knowledge of ecological risks and governance of