Using data from Regional Fisheries Management Organizations (RFMOs), scientific observer programs, and its own at-sea research and skippers workshops, the International Seafood Sustainability Foundation (ISSF) has published an updated report that documents purse-seine tuna fishing’s impact on “non-target” species. The bycatch species covered in the report are sharks, whale sharks, rays, finfish, sea turtles, and billfish. While they are not bycatch species, the report also touches upon catches of undesirably small bigeye and yellowfin tunas.
Organized by species and including graphics and a full bibliography, “ISSF 2017-06: A Summary of Bycatch Issues and ISSF Mitigation Activities to Date in Purse Seine Fisheries, with Emphasis on FADs”:
“A Summary of Bycatch Issues” is intended to be a useful reference for fishers and tuna companies, scientists, regional fisheries management organizations (RFMOs), government agencies, nongovernment organizations (NGOs) including conservation groups, and others interested in helping fisheries to be more sustainable.
The November 2017 report, authored by ISSF staff and collaborating scientists Victor Restrepo, Laurent Dagorn, David Itano, Ana Justel-Rubio, Fabien Forget, and Gala Moreno, is an update of a 2014 publication.
Not all non-target species are equally vulnerable to becoming bycatch in purse-seine fisheries, and bycatch rates for a single species can vary across oceans. For some species, other fishing methods have higher bycatch than purse-seine fishing. Here are some key findings in the report:
Since its inception in 2009, ISSF has dedicated resources and efforts to understanding bycatch issues in tuna fisheries (see “Related ISSF Activities” sections in the report). In addition to publishing scientific reports, ISSF hosts bycatch-mitigation workshops and publishes guidebooks and videos for skippers and other stakeholders. The Foundation also advocates science-based, mitigation measures to RFMOs through meetings and side events, position statements, and joint letters.
Commercial vessels catch about 4.7 million tons of tuna annually. Purse-seine vessels dominate large-scale tuna fishing, harvesting about 64% of the tropical tuna catch (skipjack, yellowfin, and bigeye tuna). Many purse seiners use Fish Aggregating Devices (FADs) or other floating objects to attract tuna to their nets, although they also may pursue sets on free-swimming tuna schools. More than half of the total tropical tuna landings globally are made by sets on FADs or other floating objects.
Bycatch occurs across most major tuna fishing methods — including longline, gillnet, and troll — and all fishing methods can affect the marine environment in multiple ways beyond bycatch.
“ISSF 2017-06: A Summary of Bycatch Issues and ISSF Mitigation Activities to Date in Purse Seine Fisheries, with Emphasis on FADs” can be downloaded from the ISSF site.
For more information on tuna stock health, see ISSF’s Status of the Stocks. For more information on FAD fishing and bycatch, see ISSF’s Questions and Answers about FADs and Bycatch.
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