BIOCHEMICAL GENETIC STRUCTURE AND VARIATION IN A NATURAL POPULATION OF SILVER CARP FROM THE MIDDLE REACHES OF THE YANGTZE RIVER

Using starch and polyacrylamide gel electrophoresis, we analyzed the Oariants of 11 isozymes encoded by 31 presumphve loci in a natural silver carp population from the middle reaches of the Yangtze River. Among the 27 loci usable for genetic populahon analysis, four (Ldh-C, Idhp-A, Est-1,-2) were polmorphic. The mean propotion of polymorphic loci and the average heterozygosity per locus in the mentioned population wer 14.8% and 0.0451, respectively. Comparative result showed that silver carp hatehery and natural populations had a similar mean proportion of polymorphic loci. It was proposed that the reduction of genetic variability in fish hatchery populations was resulted from some unreasonable factors in propagation process to a great extent and avoiding or minimizing these factors intentionally would be useful for maximzing the genetic variability in hatchery populations of cultoral fish species.