Mitigating seabird bycatch during hauling by pelagic longline vessels


Gilman, E., Chaloupka, M., Wiedoff, B., Willson, J.



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e84499. doi:10.1371/journal.pone.0084499

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The Hawaii longline swordfish fishery reduced seabird captures through mitigating bycatch during setting. Now, 75% of bycatch occurs during hauling. Observer data was fit to a generalized additive regression model and found that density of albatrosses during hauling, leader length, and year had the largest model effects. Heavier swivels, greater than 65g, had significantly fewer catch rates for seabirds. However, heavier weights with longer leaders had reduced effects. Shorter leaders with weighted swivels closer to the hooks, significantly reduced the likelihood that baited hooks could become available to albatrosses at the surface. There was no significant difference in catch rate between hauls made with vs. without blue-dyed bait. Future haul mitigation should focus of reducing bird access to hooks as crew coil branchlines.