comparative influence of ocean conditions on yellowfin and atlantic bluefin tuna catch from longlines in the gulf of mexico比较影响海洋环境的黄鳍金枪鱼,大西洋蓝鳍金枪鱼捕捞延绳钓在墨西哥湾.pdfVIP

Comparative Influence of Ocean Conditions on Yellowfin and Atlantic Bluefin Tuna Catch from Longlines in the Gulf of Mexico 1 2 Steven L. H. Teo *, Barbara A. Block 1 Department of Wildlife, Fish, and Conservation Biology, University of California Davis, Davis, California, United States of America, 2 Tuna Research and Conservation Center, Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America Abstract Directed fishing effort for Atlantic bluefin tuna in the Gulf of Mexico (GOM), their primary spawning grounds in the western Atlantic, has been prohibited since the 1980s due to a precipitous decline of the spawning stock biomass. However, pelagic longlines targeted at other species, primarily yellowfin tuna and swordfish, continue to catch Atlantic bluefin tuna in the GOM as bycatch. Spatial and temporal management measures minimizing bluefin tuna bycatch in the GOM will likely become important in rebuilding the western Atlantic bluefin stock. In order to help inform management policy and understand the relative distribution of target and bycatch species in the GOM, we compared the spatiotemporal variability and environmental influences on the catch per unit effort (CPUE) of yellowfin (target) and bluefin tuna (bycatch). Catch and effort data from pelagic longline fisheries observers (1993–2005) and scientific tagging cruises (1998–2002) were coupled with environmental and biological data. Negative binomial models were used to fit the data for both species and Akaike’s Information Criterion (corrected for small sample size) was used to determine the best model. Our results indicate that bluefin CPUE had higher spatiotemporal variability as compared to yellowfin CPUE. Bluefin CPUE increased substantially during the breeding month