Genetic population structure of goldsinny wrasse, Ctenolabrus rupestris (L.), in Norway: implications for future management of parasite cleaners in the salmon farming industry

The application of goldsinny wrasse, Ctenolabrus rupestris (L.), as parasite cleaners in the salmon farming industry has led to transport of live wrasse between regions in Norway. Owing to the operation of salmon farms, some of the transferred wrasse escape from the salmon net pens and can therefore mix and potentially interbreed with the local populations. The genetic effects of such interbreeding are unknown and information about the genetic population structure of this species in Norwegian inshore waters is needed to evaluate the potential effects. A genetic study based on polymorphic tissue enzymes was therefore carried out. Four of the 35 protein coding loci screened were polymorphic at the 99% level, and only two at the 95% level. The allele frequencies of the IDDH‐1*; PGM‐1*; GPI‐1* and GPI‐2* loci were compared in wrasse samples (1442 specimens) collected at 12 localities. Significant differences were found for PGM‐1* among the samples collected at two inner fjord localities. Significant differences at the IDDH‐1*, PGM‐1* and GPI‐2* loci were found when data from a sample of transferred wrasse caught in southern Norway were compared with local wrasse in the recipient areas.