Effects of eliminating shallow hooks from tuna longline sets on target and non-target species in the Hawaii-based pelagic tuna fishery

Longlines were set at depths greater than 100m using weighted lines to reduce bycatch of recreationally important fish species and protected species such as seabirds and sea turtles. While bigeye tuna catch rates were consistent between control and experimental sets, bycatch rates increased for sickle pomfret and opah but decreased for wahoo, dolphinfish, blue and striped marlin, and shortbill species. These species are generally not targeted but retained for their commercial value. Bycatch of sharks and pelagic stingrays did not differ between the experimental and control sets.
Field Studies:

Location	Fishing gear	Reduction technique	Bycatch species	Effect on bycatch species	Catch	Effect on target catch	Type
Hawaii	Hooks-and-Lines	Deep sets	Bony Fishes	Decreased catch of wahoo, dolphinfish, blue and striped marlin, and shortbill species, increased catch of sickle pomfret and opah, and did not affect catch of sharks and pelagic sting rays	Tuna and swordfish	Same for experimental and control sets	In the wild