Multivariate Morphometric Analysis of Striped Bass, White Bass, and Striped Bass × White Bass Hybrids

Abstract

Striped bass Morone saxatilis, white bass M. chrysops, and striped bass ♀ × white bass ♂ hybrids have been widely introduced into streams and reservoirs throughout the southeastern USA. Because these taxa often cooccur but are managed differently, distinguishing among them is necessary. Although single morphometric and meristic characters were unreliable discriminators, we could separate the three taxa using sheared principal components analysis and discriminant analysis of multiple characters. Snout and second dorsal spine lengths were greater, and postpectoral and third anal spine lengths were shorter, in striped bass than in white bass and hybrids. Distances between posterior of anal fin and posterior of second dorsal fin, and between orbit and preopercle, were greater in hybrids than in the parental species. White bass were separated from hybrids on the basis of second and third anal spine lengths, orbital lengths, base length of pelvic fin, and eye diameter, all of which tend to be greater in white bass than in hybrids. Our model for classifying unknown specimens resulted in 100% correct classification for striped bass and 85% correct classification overall. Our approach can be used to accurately separate striped bass from the other two taxa; it can also be used, but with less accuracy, to separate white bass from hybrids. In view of the uncertainty in discrimination, we recommend that management strategies and fishing regulations be set for Morone fisheries rather than for individual forms or species, especially in water bodies containing white bass and hybrids.