Abundance of the bottlenose dolphin ( Tursiops truncatus ) and proposal for a priority area of conservation in the Southern Gulf of Mexico marine ecoregion

Abstract

Demographic studies are crucial for assessment of the status of dolphin populations and their relationship with anthropogenic activities as a way to make effective management and conservation decisions. In the Gulf of Mexico, the interaction between bottlenose dolphins (Tursiops truncatus) and anthropogenic activities merits special attention. The objective of this study was therefore to determine the annual abundance and area of preference of the coastal population of T. truncatus (period 2005–2020), and to delimit a priority area for its conservation in the Southern Gulf of Mexico marine ecoregion. Abundance was calculated using the Jolly–Seber model and habitat preference was determined per climatic season (dry, rainy and cold northerly fronts) as a function of environmental variables. The association between anthropogenic activities and dolphin distribution was studied and the priority area delimited using potential distribution models. Off the coasts of Tuxpan and Tamiahua, the results show that the dolphin population numbered 306 individuals (95% CI: 162.97; 607.33) and has remained relatively constant over time. The pattern of dolphin distribution varied between seasons, possibly owing to changes in food availability. However, river mouths and lagoons are of importance to T. truncatus throughout the year. On the other hand, fishing and maritime traffic can potentially affect this species. Finally, this study shows that the delimitation of sites of importance for T. truncatus is a strategic tool with which to help conserve the species and associated coastal ecosystems.