Atlantic Coastwide Population Structure of Striped Bass Morone saxatilis Using Microsatellite DNA Analysis

Striped bass Morone saxatilis support one of the most popular and important inshore recreational and commercial fisheries along the Atlantic Coast of North America. Populations at both extremes of its distribution are largely resident while those in the center of its range (Hudson River, New York, to Roanoke River, North Carolina) are seasonally migratory, ranging from the Bay of Fundy, Canada, to the Outer Banks of North Carolina. Historically, population abundances of striped bass fluctuated widely, sometimes resulting in the imposition of severe management measures to restrict their harvest. Detailed knowledge of its rangewide population structure would aid in more effective management; however, most genetic studies addressing the structure of the migratory coastal stock have largely failed to achieve this goal. To address this need, we used multi-loci microsatellite DNA analysis. We identified six genetically distinct populations across the species' distribution, including the Miramichi, Shubenacadie, Hudson, Delaware-Chesapeake, Roanoke, and Santee-Cooper rivers. We also report significant genetic differentiation between the Nanticoke and Choptank rivers along the eastern shore of the Chesapeake Bay and collections from tributaries along the western shore of the Bay. The Annapolis and Saint John rivers, tributaries of the Bay of Fundy, historically hosted striped bass aggregations that were extirpated, or nearly so, by anthropogenic stressors in the late 20^th century. No specimens with unique genotypes were found in collections from either river; instead the vast majority were admixed with genotypes of Shubenacadie River, Hudson River, Chesapeake Bay, and Roanoke River lineage. Finally, we show in simulations that these genetic markers should be informative in quantifying the contributions of the Hudson River, Chesapeake Bay-Delaware, and Roanoke River to mixed-stock harvests that occur within the range of the coastal migratory stock.