GENETIC-VARIATION AT 3 POLYMORPHIC LOCI IN WILD AND HATCHERY STOCKS OF THE ABALONE, HALIOTIS-TUBERCULATA LINNAEUS

The abalone, Haliotis tuberculata, is a gastropod mollusc of commercia l importance in Europe with considerable potential for aquaculture. A wild population of H. tuberculata from Guernsey, Channel Islands was c ompared to two hatchery populations; one an F-1 stock produced by a ha tchery in Guernsey, the other an F-3 stock cultured at the Shellfish R esearch Laboratory (SRL) at Carna, Ireland. The F-1 and SRL stocks wer e each derived from the Guernsey wild population and reproductively is olated from this population for one and three generations, respectivel y. The three populations were screened for allozyme variation at three polymorphic loci, Gpi, Pgm and Mdh, using starch-gel electrophoresis. When compared with the wild population, both the F-1 and SRL samples were very similar in terms of mean effective number of alleles per loc us and levels of heterozygosity. However, the SRL stock did show a red uced number of rare alleles when compared to the F-1 and Guernsey samp les but without showing any evidence of inbreeding or reduction in lev els of heterozygosity. Effective population size was calculated from d irect census (N-e) and temporal changes in allelic frequencies ((N) ov er cap(k)). N-e was estimated to be 48 and 54.5 for SRL and F-1, respe ctively, whereas calculated (N) over cap(k) was 21.4 and 23.9, respect ively.