GENETIC-STRUCTURE OF BAY ANCHOVY (ANCHOA-MITCHILLI) POPULATIONS IN CHESAPEAKE BAY

To determine the genetic structure of the bay anchovy (Anchoa, mitchil li) within Chesapeake Bay, 16 isozyme systems encoding 21 loci for 20 populations were examined using horizontal starch gel electrophoresis. Contingency Chi-square analysis revealed significant allelic frequenc y differences at nine loci (AAT-1, AAT-2, ALD-1, CPK-2, GAP-1, GLY-1, LDH-1, MDH-1, and MDH-2). Two loci, ALD-1 and MDH-1, were responsible for nine of 14 tests not conforming to Hard Weinberg expectations, wit h some of these deviations attributed to possible scoring and/or sampl ing error. Estimates for mean average heterozygosity were relatively h igh, ranging from 0.040 to 0.096, with 33-57% of the loci polymorphic. A low F-st value (0.041) along with high genetic identity estimates ( (I) over bar = 0.997) indicated little substructuring of bay anchovy p opulations within Chesapeake Bay.