Incidence of live bird haul capture in pelagic longline fisheries.
For this study, incidence of live bird capture during line hauling was derived from 80 million observed hooks on which a total of 4379 seabirds were caught. Of these, 19% were alive, or 10% if excluding the Hawaii shallow set fishery. Outside the Hawaii Shallow Set fishery there is widespread evidence of live bird haul capture, although at a lower rate. The reason for higher incidence in certain fisheries, yet lower incidence in others, is not entirely clear. Annually, in pelagic longline fisheries alone there could be at least 3,500-7,350 birds caught alive and released with uncertain survival prospects. The greatest cause for concern with regard to live bird haul capture in pelagic longline fisheries is the potential for this to substantially increase as a consequence of the ACAP best practice mitigation guidelines advocating night setting. A night setting routine causes the majority of hauling to shift into daylight hours, thereby increasing the risk of bird capture during the haul. However, the benefit to seabirds from more night setting is likely to greatly exceed the potential negative consequences of increased capture during the haul. Possible combined mitigation alternatives to night setting, which also maintain a low risk of live bird haul capture do exist. A focus on the appropriate safe release of haul-caught birds would help to offset increased haul catch because of night setting. There is a critical need to rectify the deficiencies in data collection, and to ensure accurate reporting of observer data detailing haul catch. It is also essential to reach a better understanding of post-release survival rates and to further investigate the prevalence of live haul capture in specific fisheries and the potential for this problem to increase in fisheries more widely.