Workshop on turtle bycatch mitigation for longline fisheries: experimental design and data analysis, 7-8 November 2007, San Ramón de Alajuela, Costa Rica

Abstract

Large numbers of fishing vessels operating from ports in Latin America participate in surfacelongline fisheries in the eastern Pacific Ocean (EPO), and several species of sea turtles inhabitthe grounds where these fleets operate. The endangered status of several sea turtle species, andthe success of circle hooks (‘treatment’ hooks) in reducing turtle hookings in other ocean areas,as compared to J-hooks and Japanese-style tuna hooks (‘control’ hooks), prompted the initiationof a hook exchange program on the west coast of Latin America, the Eastern Pacific RegionalSea Turtle Program (EPRSTP)1. One of the goals of the EPRSTP is to determine if circle hookswould be effective at reducing turtle bycatch in artisanal fisheries of the EPO withoutsignificantly reducing the catch of marketable fish species. Participating fishers were providedwith circle hooks at no cost and asked to replace the J/Japanese-style tuna hooks on theirlonglines with circle hooks in an alternating manner. Data collected by the EPRSTP showdifferences in longline gear and operational characteristics within and among countries. Theseaspects of the data, in addition to difficulties encountered with implementation of the alternating-hookdesign, pose challenges for analysis of these data.