This week Bonefish & Tarpon Trust (BTT) shared the results from its two-year Tarpon Genetic Program that, thanks to the efforts of anglers, guides, lodges, and researchers, saw more than 23,000 scale samples collected from across the world. Nice work people.
That pile of tarpon body armor provided a massive dataset for researchers studying how many distinct tarpon populations actually exist. And according to Dr. Liz Wallace, the long-awaited answer is:
"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," she writes. "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), the new BTT study used a more extensive dataset and advanced analytical methods to reveal trans-Atlantic connectivity and one region-wide tarpon stock.
As for what the results mean for tarpon conservation, BTT says that the high level of connectivity equals a need for a broader approach to help bolster population health.
"Effective management for increasing populations will require an international scope," it says. "Recreational and commercial harvest still occurs and remains unregulated in parts of the region—the continued harvest of tarpon in up-current areas like Louisiana, Mexico, and Cuba may negatively impact the tarpon population and fishery down-current in areas like Florida and The Bahamas if enough tarpon are harvested to cause a decline in how many juveniles are produced each year."