Bluefin Tuna Spawning Environments in the Gulf of Mexico: Links to Larval Ecology and Recruitment Processes

Atlantic bluefin tuna has the most spatially and temporally restricted spawning grounds of any Atlantic tuna. Although adult fish can tolerate near-freezing water temperatures, they migrate long distances to reach sub-tropical waters to spawn. In the western Atlantic, larvae have been collected only in the Gulf of Mexico and immediate surrounds, during spring. Selection of this narrow spatiotemporal window for reproduction implies the presence of favorable conditions for larval survival. However, links between environmental conditions, larval ecology and ultimate recruitment are poorly understood.

In this study, we used a combination of historical survey records and habitat modeling techniques to define environmental constraints on bluefin tuna spawning grounds in the Gulf of Mexico. Measurements of larval growth and feeding success were then used to describe variability in finer-scale processes, with implications for larval survival and recruitment. Results have direct relevance to current day management issues, in terms of examining stock-recruit relationships, and for prediction of observed high recruitment events. In addition, improved understanding of the connections between environmental variability, larval ecology and recruitment processes can inform future management strategies. This is particularly important for bluefin tuna, which shows high potential vulnerability to climate change.