Low genetic variability in Scandinavian populations of Ostrea edulis L. - possible causes and implications

Abstract 11 populations of the European oyster Ostrea edulis L. from Norway and Sweden revealed a very low level of genetic variation in 21 enzyme loci. Only one locus, Pgm, was polymorphic (0.95 criterion) in all populations. The Norwegian populations, which were from oyster farms, were slightly less variable than the natural Swedish populations. An imported Scottish population revealed small differences to the Nordic ones. The causes of the low level of genetic variation are discussed and it is suggested that human activities, for example, overfishing and transplantation, in combination with diseases may have played an important role in depleting the genetic variation within and between these populations, which are somewhat less variable than Central European populations. The results of this study suggest that artificial selection — an important tool of mariculture development - may not be particularly successful in populations of O. edulis , especially not from Sweden and Norway.