Analysis of the enzyme polymorphism in a plaice, Pleuronectes platessa L., population from the north‐west coast of Brittany, France

A study of enzyme polymorphism by electrophoretical techniques permitted the genetic structure and the homogeneity degree of the plaice population present in the Abers Wrac'h and Benoit along the north‐west coast of Brittany to be determined. Thirteen enzymic systems encoded by 21 loci were analysed and nine of these loci were polymorphic at the 5% level. The comparison of allelic frequencies and of observed heterozygosity hobs did not show significant differences between these two individual groups. Nei's genetic identity (I= 0.998) and distance (D= 0.002) as estimated from allelic frequencies showed that the plaice of the two estuaries are very similar. Thus, the plaice of A. Wrac'h and of A. Benoit belong to the same population in which the average level of polymorphism per locus P is 47% and the observed average heterozygosity per individual Hobs is 0.163 ± 0.094.