Distribution of yellowfin tuna (Thunnus albacares) in the southern Gulf of Mexico based on ecological niche models and pop-up satellite archival tags.

Zurisaday Ramírez-Mendoza1, Oscar Sosa-Nishizaki2, Arturo Fajardo-Yamamoto1, Alfonsina Eugenia Romo-Curiel1, María Concepción García-Aguilar1 and Mario Rafael Ramírez-León3, (1)Center for Scientific Research and Higher Education at Ensenada, Department of Biological Oceanography, Ensenada, BJ, Mexico, (2)CICESE, Biological Oceanography, Ensenada, BJ, Mexico, (3)Center for Scientific Research and Higher Education at Ensenada, Biological Oceanography, Ensenada, BJ, Mexico
Yellowfin tuna (Thunnus albacares, YFT) is a highly migratory pelagic fish and a top oceanic predator. Economically, YFT is the most important species for the Mexican commercial longline fishery in the Gulf of Mexico. To assess the YFT distribution in the southern Gulf, we modeled the environmental suitability patterns for the species using the ecological niche model algorithm Maxent. Additionally, we used pop-up satellite archival tags to estimate its movement patterns and temperature-depth preferences. Niche models were constructed using available data from the presence of YFT and 5 environmental variables: absolute dynamic topography, sea surface temperature, chlorophyll-a concentration, salinity, and depth. The Maxent model performed was significantly better than random and produced an area under the curve score of 0.81. Sea surface temperature and absolute dynamic topography were the variables that most influenced the YFT distribution. The model predicted high suitability areas (>80%) located between the platform and the continental slope of Tamaulipas, and in the central region of the Yucatan Channel. We tagged 9 adults YFT. Tags lasting between 13 hours and 21 days, yielded data across 61 days and recorded movements from 260 to 1,145 km. The animals moved in a temperature range from 11 to 32°C, but most of the time (60%) they were in waters >24°C.The total time that they spent above 100 m was less during day hours (62%) than night (97%), suggesting greater exploration of deeper waters (350 m max depth) during daylight hours. This study can help to prioritize areas with ecological importance for the YFT. The integration of its vertical and horizontal movements with catch and effort statistics could be useful to reduce the uncertainty associated with the estimation of relative abundance in stocks assessment models.