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Research was conducted in the western North Atlantic Ocean to determine what effect changes to the hook design and bait type would have on pelagic longline bycatch. Three types of hooks, 18/0 and 20/0 circle hooks and 10/0 Japanese tuna hooks with squid and mackerel bait were tested against the standard 9/0 J-hook with squid bait. Circle hooks and mackerel bait, individually, significantly reduced loggerhead and leatherback sea turtle bycatch. Combined, 18/0 circle hooks and mackerel bait reduced loggerhead sea turtle bycatch, while swordfish (a targeted species) catch by weight increased. Combined 18/0 circle hooks with squid bait significantly decreased swordfish catch rates but significantly increased blue shark, bluefin tuna and albacore tuna catch rates. Blue shark, bigeye and albacore tuna catch rates were always reduced when mackerel bait was used but porbeagle and shortfin mako shark catch rates increased with this bait type.