Purse Seine Guidebook
There is a greater number and variety of bycatch species in FAD-associated sets than in unassociated sets, including small yellowfin and bigeye tuna, sharks, turtles, billfish, and bony fish. By weight, the primary impact of FAD fishing is largely on non-targeted, small tuna. This represents 5% to 68% of a total bycatch, while it corresponds to between 0.06% and 5% of the total catch.
Other species of fish, sharks, and other marine life are also captured; the bycatch amount of each species can vary widely depending on the region, time of the year, vessel, crew experience, and other factors. Typically, bycatch in associated sets is made up of other fish, sharks, and rays, averaging about 5% of the total catch, ranging from 1.1% to 7.4% depending on the ocean. For comparison, unassociated sets result in less bycatch, ranging on average from 0.3% to 1.8%.
Research is ongoing to investigate additional FAD fishing techniques that can reduce the bycatch attracted to, or the catch associated with, FADs. The current best practices to mitigate FAD-related bycatch will be presented in Chapter 3.
Bycatch underneath a conventional FAD. Photo: Fabien Forget (ISSF)
Non-tuna bycatch rates in purse-seine fisheries, as shown in ISSF Technical Report 2021-11