An excess of homozygotes at a serum esterase locus in the Atlantic mackerel Scomber scombrus

Abstract

SummaryA serum esterase polymorphism in the Atlantic mackerel Scomber scombrus revealed a significant excess of homozygotes in seven of eleven area samples collected in the N.E. Atlantic. Breaking down the data by sex, year class, size within year class and haul did not remove the homozygous excess. The presence of a null allele is unlikely due to the high frequency required and the lack of null allele homozygotes. It is suggested that the homozygous excess might arise from a shifting selection on different batches of larvae produced over the spawning area and season.