This map displays the genetic profiles from one microsatellite locus, Mat-22. Each pie chart is a tarpon collection area, and each color wedge is a unique microsatellite allele (repeat unit). Alleles were shared among all sites across the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea.
How many distinct tarpon populations exist?
Only one! A rigorous and comprehensive suite of statistical approaches was used to analyze the data. The overall level of genetic diversity in the Atlantic tarpon indicated high levels of gene flow (mixing over generations through interbreeding) across the entire region. Fish from Virginia to Louisiana and all across the Caribbean to Brazil displayed shared genetic profiles. Even tarpon samples collected from across the Atlantic Ocean, along the West African coast, shared these profiles. The results reveal that a single Atlantic tarpon stock exists. Although a preliminary study by McMillen-Jackson in 2005 suggested two stocks (West and East Atlantic), our study used a much more extensive dataset and advanced analytical methods to reveal trans-Atlantic connectivity and one region-wide tarpon stock.