Use of Mitochondrial DNA Polymorphisms to Estimate the Relative Contributions of the Hudson River and Chesapeake Bay Striped Bass Stocks to the Mixed Fishery on the Atlantic Coast

Abstract

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) was used to characterize stocks of striped bass Morone saxatilis and to estimate their relative contributions during the fall of 1989 to the mixed coastal fishery at eastern Long Island, New York. Mitochondrial DNA was obtained from reference samples of striped bass collected during the spring of 1989 from the Hudson River, New York, and four spawning areas of the Chesapeake Bay (Choptank, Rappahannock, and Potomac rivers and the upper Chesapeake Bay). Five mtDNA major length genotypes were detected in these fish, and significant differences in their frequencies were observed between the Hudson River and Chesapeake Bay samples. An mtDNA minor length genotype found in some fish (13%) from the Chesapeake Bay and absent from all Hudson River samples provided a second discriminatory character. By using a constrained generalized least squares approach, we estimated that the Hudson River and Chesapeake Bay stocks contributed 73% (95% confidence interval 50–87%) and 27% (95% confidence interval 13–51 %) respectively, of the mixed fishery sample. The probability of the Hudson River contribution exceeding the Chesapeake Bay contribution in this sample was more than 95%. These results suggest that the Hudson River contribution to the mixed coastal fishery was greater in 1989 than reported in earlier studies. We also found no differences in mtDNA major length genotype frequencies among as many as 11 year-classes within the Hudson River, Chesapeake Bay, or Roanoke River spawning systems. These results indicate that mtDNA RFLP genotypes in these striped bass stocks are temporally stable within a fisheries context. An advantage to mtDNA analysis over phenotypic approaches is that, because mtDNA genotype frequencies are not subject to environmentally induced variation, efforts subsequent to an initial survey can focus on characterizing the mixed coastal fishery.