Trial setting of deep longline techniques to reduce bycatch and increase targeting of deep-swimming tunas

Pelagic longlines targeting bigeye tuna (Thunnus obesus) and lustrous pomfret (Eumegistus ilustris) in Hawaii were weighted with lead weights, enabling fishing deeper in the water column than traditional pelagic longlines.  Weighted longlines caught 31 target species with a slightly higher catch per unit effort (CPUE) of 1.3 fish/100 hooks (49 kg/100 hooks) compared to traditional gear (38 target species and a CPUE of 1.08 fish/100 hooks or 41 kg/100 hooks).  Bigeye tuna CPUE for the weighted gear was higher, 0.95 fish/100 hooks (36 kg/100 hooks), compared to traditional gear, 0.56/100 hooks (21 kg/100 hooks).In a second trial in a fishery targeting tuna and billfish, swordfish (Xiphias gladius) CPUE was very similar for weighted (0.3 fish/100 hooks or 17 kg/100 hooks) and traditional (0.25 fish/100 hooks or 14 kg/100 hooks) gear.  This technique could be used to reduce sea turtle and other bycatch species interactions, however this was not tested during this initial trial study.