Effects of hook and bait in a tropical northeast Atlantic pelagic longline fishery: Part I - Incidental sea turtle bycatch

Experimental studies were conducted over a three year period (August 2008-December 2011) to determine the effects of changing traditional J-hooks baited with squid bait to circle hooks (offset and non offset) with mackerel bait on sea turtle interactions. Studies were carried out aboard pelagic longline vessels targeting swordfish in the tropical northeast Atlantic Ocean. Overall, sea turtle interactions were reduced when circle, compared to J-hooks were used. However species specific differences did occur. Leatherback interactions were only reduced when circle hooks with an offset were used. Leatherback interactions can be reduced by 55% in this fishery by switching from J-style to circle hooks. Hardshell turtle interactions were reduced when both circle hook styles and mackerel bait were used. Interactions with hard shelled turtles can be reduced by 50-55% in this fishery by switching from J-style to circle hooks.  A 55% reduction in hardshell turtle bycatch is expected to occurr in this fishery by switching from squid to mackerel bait.