Genetic Population Structure of Black Drum in U.S. Waters

Abstract

The Black Drum Pogonias cromis is an estuarine-dependent fish that supports recreational and commercial fisheries throughout its range along the U.S. Atlantic coast and Gulf of Mexico (GOM) coast. We used nuclear microsatellite markers and samples collected from multiple locations along both the U.S. Atlantic and GOM coasts to evaluate the stock structure of Black Drum and to examine small-scale spatial genetic population structure along the U.S. Atlantic coast. As no microsatellite primers had been developed for Black Drum, primers for Spotted Seatrout Cynoscion nebulosus and Red Drum Sciaenops ocellatus were screened, selected, and optimized for use with Black Drum DNA. Six polymorphic loci were identified and used to genotype samples. Results suggested (1) significant genetic divergence between Black Drum populations from the U.S. Atlantic coast and the GOM coast; and (2) either recent or current gene flow between the two regions. Along the U.S. Atlantic coast, there appeared to be weak but significant genetic divergence among Black Drum from southern states, specifically between individuals from the Carolinas and Florida. An isolation-by-distance pattern was also observed for Black Drum from North Carolina to Florida. On a larger scale, results suggested a lack of genetic divergence between individuals from Delaware and Virginia and those from the southern Atlantic states, which may be attributable to the life history patterns of Black Drum. Our results support the management of Black Drum in U.S. waters as two separate stocks: Atlantic and GOM. The results also support the management of Black Drum along the U.S. Atlantic coast as a single unified stock and indicate the need for common management regulations among the Atlantic states.

Received August 26, 2014; accepted February 4, 2015

ACKNOWLEDGMENTS

We thank the following for providing samples: the New Jersey Department of Environmental Protection's Division of Fish and Wildlife; the Delaware Department of Natural Resources and Environmental Control's Division of Fish and Wildlife; the Maryland Department of Natural Resources; the Virginia Marine Resources Commission; the North Carolina Department of Environment and Natural Resources’ Division of Marine Fisheries; the South Carolina Department of Natural Resources’ (SCDNR) Marine Resources Division (Inshore Fisheries Research Section); the Georgia Department of Natural Resources; the Florida Fish and Wildlife Conservation Commission; the Alabama Department of Conservation and Natural Resources’ Marine Resources Division; the Fisheries Ecology Laboratory at Dauphin Island Sea Laboratory; the Gulf Coast Research Laboratory, University of Southern Mississippi; and Texas Parks and Wildlife. We also thank Erin Koch (SCDNR) for assistance in making the maps. Funding was provided by the South Carolina Saltwater Recreational Fisheries Advisory Committee; the Graduate Student Association at the College of Charleston; the Slocum–Lunz Foundation; and the Charleston Scientific and Cultural Education Fund. This document is Contribution Number 729 of the SCDNR Marine Resources Research Institute.