Effect on bycatch species:
Circle hooks decreased loggerhead and leatherback catch; even more effective for loggerheads when combined with mackerel bait
Effect on target catch:
Circle hooks combined with mackerel bait increased swordfish catch by weight. With squid, decreased swordfish catch, increased bluefin and albacore tuna catch. Mackerel bait decreased bigeye and albacore tuna catch.