Genetic variation at isozyme loci in blue whiting from the north-east Atlantic

Genetic variation in blue whiting Micromesistius poutassou was investigated by starch gel electrophoresis of enzymes in tissue extracts. A total of 130 specimens from the spawning areas west of the British Isles were collected from trawl catches in 1990 ( n = 30) and 1992 ( n = 100). In 25 tissue enzyme loci screened for genetic variants in the 1990 sample, polymorphisms (0.95 criterion) were found at IDDH-2 *, IDHP-2 * and PGM-1 *, giving a frequency of polymorphic loci of P _0.95= 0.12. In pooled samples the average heterozygosity per locus was estimated at H _e =0.043 and the effective number of alleles per locus at 2.20, 1.45 and 1.53, respectively, for IDDH-2 *, IDHP-2 * and PGM-1 *.