Failure of Quantitative Phenotypic Characteristics to Distinguish Black Crappie, White Crappie, and Their First-Generation Hybrid

Commonly used quantitative phenotypic characteristics, including dorsal hard spine count and a nape measure (the ratio of the dorsal fin base length to the distance of the fin origin to the eye) failed to consistently distinguish between black crappie Ponioxis nigromaculatus and white crappie P. annularis in Alabama reservoirs. A high percentage (67%) of first-generation (F1) hybrid crappies were correctly identified with an alternate combination of these two characteristics, but this combination could not discriminate F1 hybrids from parentals. Correct identification of crappie parentals and their F1 hybrids was verified by examination of allozymes. In Lake Weiss, 43% of the crappies were misidentified when both characteristics were used. In Jones Bluff and Gainesville lakes, 13 and 11%, respectively, were misidentified by dorsal spine counts. Our results suggested that spine counts and nape measures are not entirely reliable for distinguishing crappie species or their hybrids in Alabama reservoirs where the two crappie species coexist.