NATURAL HYBRIDIZATION BETWEEN BLACK CRAPPIE AND WHITE CRAPPIE IN WEISS LAKE, ALABAMA

Starch-gel electrophoretic analysis of 1,081 crappies collected from O ctober 1990 through November 1991 revealed that black crappie Pomoxis nigromaculatus and white crappie P. annularis were hybridizing in Weis s Lake, Alabama. Crappie hybrids made up 22% of the population and wer e found in the 1988 to 1991 year-classes. First-generation (F-1) hybri ds were seven times more abundant than second-generation and higher (F -x) hybrids. The F-1 hybrids expressed superior growth and survival, a nd they recruited into the fishery (254-mm total length minimum size l imit) earlier than the parental species. Distributions of alleles amon g F-x hybrids indicated that F-1 hybrids were more likely to successfu lly mate and produce offspring with black crappies than with white cra ppies. Factors that may have contributed to hybridization between crap pie species include failure to identify specific mates due to low wate r clarity during spring when these fish spawn, short and overlapping s pawning times, and fluctuating water levels. In addition, Weiss Lake i s located at the interface of sympatric and allopatric crappie populat ions and this has been associated with interspecific hybridization amo ng other fish species.