October 10, 2019 — In recent years, concern has been growing about bycatch of juvenile bigeye tuna by purse-seiners setting nets on drifting fish aggregation devices (dFADs). The main target of the purse-seiners is the more plentiful skipjack tuna, but as bigeye inhabit the same tropical seas, they are often taken as well.
The devices typically consist of a raft or buoy trailing a length of disused netting tied into the shape of a string of sausages, used to attract tuna – which like to gather under floating objects. Modern dFADs are equipped with a solar-powered GPS device and a fish finder to report their location and the amount of fish gathered under them. Support vessels manage the deployment and retrieval of the dFADs, so that fishing vessels can concentrate on fishing.