The effect of mitigation measures on seabird by-catch in the Hawaii longline fishery

Incidental catches of protected seabirds are inextricably linked with many commercial fisheries.  Because of this link, fishing limits, seasons, etc. may be dictated by the scope of these interactions.  The Hawaii pelagic longline fishery has interactions (hookings and/or entanglements) with two and potentially three species of protected albatross (black-footed, Laysan, short-tailed).  Several measures have been instituted attempting to reduce interactions with seabird species.  Requirements of weighted dropperlines, blue-dyed bait, strategic offal/bait discard, bird scaring devices (i.e. bird curtain, tori line), and night setting of hooks have been employed with varying levels of success.  By examining observer data since the program inception in 1994, efficacy of these measures has been determined.  In the years before mandatory mitigation measures were introduced (1994-1997), seabird interactions occurred an average of 0.27 incidents/1000 hooks set.  Since current mitigation requirements were enacted in 2004, interactions average 0.008 incidents/1000hks- approximately 3% of initial levels.   Night setting of hooks and setting under a bird curtain have been the most effective methods of curtailing these interactions.  The success of the Hawaii longline fishery in instituting and monitoring these mitigation measures has been paramount in reducing seabird bycatch.  Continued monitoring and improvement of techniques may further reduce these interactions.