Esterase gene frequencies and temperature relationships in the New Zealand snapper Chrysophrys auratus

Esterase and glucosephosphate isomerase loci were examined in different year classes of the snapper Chrysophrys auratus Forster from the Hauraki Gulf in New Zealand and compared with temperatures during the immediate post-spawning period, the time when snapper larvae suffer high mortality. Year classes spawned in warm years have a low frequency of the Est-4² allele and year classes from cold years a high frequency of Est-4². Gpi-1² frequencies showed no significant change between warm and cold years. Annual fluctuations in allele frequencies within stocks may account for the observed excess of esterase homozygotes in other marine teleosts.