Population Genetics of Southern Flounder with Implications for Management

Abstract

The southern flounder Paralichthys lethostigma is a marine flatfish that ranges from North Carolina to the Yucatan Peninsula in the Gulf of Mexico. Management of southern flounder will be improved by proper delineation of management units based on genetic data. We used microsatellite DNA markers to determine how many populations exist across the species’ range and the geographic extent of those populations. Based on significant genetic divergence across loci (F _CT = 0.035), two discrete populations of southern flounder occur. The populations inhabit the Gulf of Mexico and Atlantic Ocean, with the boundary between them located in southern Florida, an area that is generally devoid of southern flounder. Within the Gulf of Mexico, there was little evidence of discrete populations but weak evidence for isolation by distance. These data indicate that specieswide management of southern flounder should account for the independent demographic entities in the Gulf and Atlantic and that local management strategies should account for the upper limits to dispersal within the Gulf.

Received January 12, 2012; accepted April 12, 2012

ACKNOWLEDGMENTS

This work was funded by funds from the Federal Aid in Sport Fish Restoration Act, Grant F-179-R, and matching funds from Texas Parks and Wildlife. The authors thank routine monitoring staff of Texas Parks and Wildlife, Coastal Fisheries Division. I. Blandon provided samples from North Carolina. S. Fisk, N. Gargasz, K. Gregalis, and D. Marotta provided samples from Florida, which were collected with cooperation from the Florida Fish and Wildlife Conservation Commission. M. Fisher and multiple anonymous reviewers provided helpful comments on the manuscript draft. Reference to trade names does not imply endorsement by the state of Texas.