Exploring spatio-temporal patterns of the mexican longline tuna fishery in the gulf of Mexico: A comparative analysis between yellowfin and bluefin tuna distribution

Abstract

Data from the Mexican longline fishery in the Gulf of Mexico (GoM) between 1994 and 2012 were analyzed to identify the spatio-temporal behavior of fishing effort and catch per unit effort of yellowfin (YFT) and Atlantic bluefin tuna (BFT), focused on habitat overlap. The applied fishing effort showed significant seasonal differences, being greater and spatially concentrated during summer months (May to August), decreasing by around 30% during the winter period (December to April), when its spatial distribution covers a larger area, probably targeting a higher number of species. The spatio-temporal distribution of YFT showed a recurrent pattern throughout the study period, with two relative abundance peaks: One in June, related to a strong aggregation process along the coast of Veracruz, and the other in November, associated with a broader distribution along the Mexican GoM. BFT occurs mainly during the winter, reaching its highest relative abundance in March, at the beginning of the spawning season. A substantial overlap between the distributions of both species was observed, warranting further oceanographic habitat characterization to be supported. The results, consistent with those obtained in U.S. waters, provide the basis for the development of specific management measures to reduce BFT bycatch in the GoM.