DEVELOPMENTAL STABILITY AND ENVIRONMENTAL-STRESS IN SALMO-SALAR (ATLANTIC SALMON)

We have studied the developmental stability (measured as fluctuating a symmetry of five meristic characters) of three populations of Atlantic salmon Salmo salar (rivers Imsa, Lone and Ogna, western Norway). All three populations were both sampled in the wild, and hatched and reare d in a common environment in a hatchery (with water from the river Ims a) from fertilization until smoltification. Both the Imsa and Lone hat chery populations have been sea-ranched in the Imsa for 10 years, wher eas the Ogna populations is novel to the hatchery environment. Individ ual biochemical heterozygosity was scored at 50 loci, of which 11 were polymorphic. There was no correlation between biochemical heterozygos ity and fluctuating asymmetry at the individual level, neither when te sted within groups nor when tested between groups. There were no diffe rences in fluctuating asymmetry between wild and hatchery Imsa and Lon e fish, indicating that the hatchery environment did not disrupt early developmental homeostatic processes. However, the Ogna hatchery fish had significantly elevated levels of fluctuating asymmetry compared to the wild Ogna fish, indicating that the hatchery environment was host ile. The Ogna hatchery fish also had significantly higher fluctuating asymmetry than the Imsa hatchery and the Lone hatchery fish. Maladapta tion to the hatchery environment is the most likely explanation for th e increased asymmetry in river Ogna fish.