Stock composition of Atlantic coastal migratory striped bass using microsatellite DNA analysis

The Atlantic Coast Migratory Stock (ACMS) of striped bass Morone saxatilis is supported by spawning populations in Chesapeake Bay and the Hudson, Delaware, and Roanoke rivers. Spawning success and recruitment differs among these populations and temporally within them and thus their relative abundances shift over time. The ACMS is subject to harvest and other sources of mortality at many Atlantic Coast locales. Effective management of these populations would benefit from knowledge of the relative contributions of these populations to the ACMS. We used microsatellite DNA analysis to measure the extent of genetic differentiation among those populations that contribute to the ACMS and to quantify their contributions to recreational harvest in 2019 at Montauk, New York. We found genetic homogeneity between the Delaware River and Chesapeake Bay populations, but significant allelic differentiation among the Hudson River, combined Delaware River-Chesapeake Bay, and Roanoke River populations. In simulations of single mixture samples, assignment accuracies for the Chesapeake-Delaware, Hudson River, and Roanoke River collections were high at 96 % (95 % CI=0.921, 0.999), 93 % (0.863, 0.979), and 81 % (0.726, 0.866), respectively. Mixture analysis and Individual Based Assignment testing were used to quantify contributions to the 2019 Montauk fishery. Mixture analysis indicated 86 %, 8.5 %, and 5.5 % contributions for the Chesapeake-Delaware, Hudson River and Roanoke River populations, respectively. Similarly, Individual Based Assignments showed the Chesapeake-Delaware population as the largest contributor (78 %), followed by the Hudson River (12 %), and the Roanoke River (10 %). Furthermore, we found no significant differences in relative contributions across the five-month recreational fishing season nor among size-classes of striped bass. Lastly, the risk of consuming a Hudson River striped bass from Montauk containing a considerably high concentration of PCBs is minimal. Future stock composition analysis of Atlantic migratory striped bass would benefit from standardization of the approach, with DNA analysis from collections made at a single strategic location offering advantages.