Growth rate and heterozygosity in the plaice, Pleuronectes platessa

Samples of young plaice were examined to see if there was any relationship between growth rate and individual heterozygosity, screened across five polymorphic enzyme loci (Pgm-1, Ada, Mdh-2, Pgi-2, Gpdh-l). Two out of 46 samples showed a significant negative correlation between growth rate and multi-locus heterozygosity; none showed a significant positive correlation. There was no overall tendency to negative or positive correlations. The largest sample (N=689) showed no relationship between multi-locus heterozygosity and growth rate, although one of the five loci, Gpdh-1, showed a significant positive correlation. The only significant correlation in the next largest sample (N= 248) was between multi-locus heterozygosity and growth rate, and that was negative. Fish of intermediate growth rate were not significantly different in heterozygosity from faster or slower growing fish. There was no relationship between variability in growth rate and multi-locus heterozygosity. These findings are discussed in the context of similar surveys from other species, and the conclusion drawn that the universality of a positive relationship between growth rate and multi-locus heterozygosity remains to be established