Abstract

Yellowfin tuna (Thunnus albacares) are highly migratory cosmopolitan fish that are currently managed as a single panmictic stock in the Atlantic Ocean; however, our understanding of the migration patterns and connectivity of Atlantic populations is minimal. Naturally occurring chemical tracers in otoliths provide valuable information that is widely used to classify populations and reconstruct environmental histories of fishes. The aim of this study is to evaluate the oto-lith microchemistry of young-of-the-year (YOY) yellowfin tuna to determine whether chemical signatures are distinct across different putative spawning areas in the Atlantic Ocean. YOY yellowfin tuna otoliths were collected from five locations in the Atlantic Ocean (Gulf of Mexico, Brazil, Martinique, Dominican Republic, and Gulf of Guinea) in 2012 and 2013 and trace elemental and stable isotopic analyses will be conducted to investigate regional variation in the chemical composition of otoliths. In this paper, we present preliminary results from the first year of our study and eval-uate the feasibility of using these natural tracers to discriminate juveniles from different nursery areas. This research is ongoing and we will extend our sampling into 2014 and 2015 at all locations. After we establish our baseline of natal signatures, these data will be used to assign adult yellowfin tuna from the Gulf of Mexico to their nursery of origin. Results of this study will ultimately provide an improved understanding of the stock structure and movement of yellowfin tuna in the Atlantic Ocean.

PDF Preview