Genetic Analysis of Reproduction of Hybrid White Bass x Striped Bass in the Savannah River

Abstract

Hatchery-reared F1 hybrids of male white bass Morone chrysops x female striped bass M. saxatilis are stocked routinely in the Savannah River drainage by agencies of Georgia and South Carolina. Concern has arisen that these F1 hybrids themselves may be reproducing, and that possible increases in abundance of F2 hybrids or backcrosses could disturb white bass and striped bass parental stocks through ecological competition or genetic introgression. We identified and employed genetic markers at four protein-electrophoretic systems to search for recombinant genotypes indicative of successful hybrid reproduction. The genetic basis and reliability of the allozyme markers were confirmed by analysis of hatchery-reared F2 hybrids, and by examination of geographic variation in allele frequencies in populations from several southeastern states. Only 6 of 642 fish assayed from the Savannah drainage had recombinant genotypes. However, in two of four test cases involving Morone samples from other locales, the genetic data revealed more extensive hybrid reproduction than in the Savannah system. Received October 8, 1983 Accepted June 20, 1984