Predicting albatross bycatch hotspots across the North Pacific Ocean [WCPFC-SC20]

Bycatch threatens many seabird populations and remains a barrier to fisheries sustainability. Albatrosses are particularly vulnerable to bycatch in longline fisheries across the North Pacific due to their wide-ranging movements and attraction to fishing vessels. Identifying when, where and in which fisheries bycatch risk is greatest is crucial to prioritize monitoring and recommend targeted management interventions. Here, we collated >1,200 albatross tracks from eleven populations of three species (short-tailed, Laysan, and black-footed) in the North Pacific to provide an oceanbasin-scale assessment of bycatch risk. We overlaid species distribution model predictions of bird densities for each population and breeding stage with Automatic Identification Systems data on pelagic longline fishing effort and created indices of bycatch risk. Albatross distribution models had strong predictive power (mean [range] area under receiver operating characteristic curve: 0.91 [0.75-0.98]). We identified bycatch risk hotspots from pelagic longline fisheries in the central and northwest subtropical Pacific that occurred mostly during breeding (winter-spring); though the months with elevated risk differed according to population and fishing vessel flag state. Considerable (88%) overlap with pelagic longline fishing effort occurred in the High Seas where observer coverage is extremely low (5%) and use of bycatch mitigation is variable. Three flag states (Japan, USA and Taiwan) were responsible for >90% of total risk. Our results indicate that improved monitoring and increased adoption of and compliance with best-practice mitigation measures in high-risk fleets would reduce future conflicts between fisheries and albatrosses.

We recommend the WCPFC-SC20: - Prioritize increasing observer coverage of the longline fleets of Japan (particularly the small offshore fleet; 10-19 gross register tonnage) and Taiwan. - Mandate adoption of best-practice seabird bycatch mitigation measures in all North Pacific longline fleets, particularly the fleets of the US, Japan and Taiwan, particularly in high-risk areas and seasons.