Field Identification Accuracy for White Bass and Hybrid Striped Bass

Fisheries Outstanding Technical Paper

We estimated the accuracy of field identification of white bass (Morone chrysops) and palmetto bass (M. chrysops X M. saxatilis) by Texas fisheries workers and evaluated the reliability of meristic and morphometric characteristics commonly used to differentiate between these 2 fishes. Electrophoretic and isoelectric focusing analyses of diagnostic proteins were used to verify the fisheries workers' identification of fish (1,087) sampled from 16 reservoirs thoughout Texas. Overall, accuracy of field identification was high and fisheries workers correctly identified all sampled white bass; however, 5% of hybrid striped bass were incorrectly identified as white bass, and 12% of these fish were found to be Fx hybrids. The majority of white bass (78%) exhibited 1 basihyal tooth patch while most hybrid striped bass (89%) had 2 patches. Hybrid striped bass had a significantly higher number of lateral stripes extending to the tail, and a significantly higher incidence of broken lateral stripes than did white bass. Genetic analysis showed a low incidence (1.8%) of Fx hybrids, indicating reproduction of hybrid striped bass is an uncommon event in Texas reservoirs. Although isoelectric focusing was not able to detect any Fx hybrids outright, this method, when used in conjuction with protein electrophoresis, served as an additional diagnostic locus which enabled us to detect backcrosses. Mangers desiring to regulate white bass and palmetto bass with different harvest restrictions should consider basing regulations on a single characteristic and accepting the consequent harvest of some unprotected individuals, since identification based on a single characteristic or combination of characteristics does not result in 100% accuracy. Alternatively, managers might consider setting Morone harvest regulations based on length and bag limits, without regard to species to reduce angler confusion and the concerns of law enforcement.

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