Effects of 16/0 Circle Hooks on Pelagic Fish Catches in Three South Pacific Albacore Longline Fisheries

The present study tested the effects of using large 16/0 circle hooks on catch rates in three pelagic longline fisheries in the south pacific ocean. large (16/0) circle hooks were tested against a variety of smaller hooks already in use by longline vessels in american samoa, cook islands, and new caledonia. The majority of these fleets use a mix of hook sizes, including circle hooks that are smaller than a 16/0 circle hook. Vessels alternated hooks throughout every set, maintaining a 1:1 ratio of 16/0 circle hooks to their existing hooks. information on catch by hook size, fish lengths, and condition at gear retrieval was collected. in total, 4912 fishes of 33 species were observed on 145,982 hooks from 67 sets. in the cook islands fishery, there was no significant difference in catch by hook type for two main target species, but there was an increase in catchability for swordfish, Xiphias gladius (linnaeus, 1758). in the new caledonia fishery, there was no significant difference in catch by hook size for any species. in the american samoa fishery, 16/0 circle hooks did not significantly affect the catch of albacore, Thunnus alalunga (bonnaterre, 1788), but did significantly reduce the catch of skipjack tuna, Katsuwonus pelamis (linnaeus, 1758), dolphinfish, Coryphaena hippurus (linnaeus, 1758), and wahoo, Acanthocybium solandri (cuvier, 1832). for all locations, catch rates on 16/0 circle hooks were nominally lower, but not always significant for smaller pelagic species.