Movements of two strains of radio tagged Atlantic salmon, Salmo salar L., smolts through a reservoir

Smolt migration through a shallow and turbid hydro-reservoir in a major Danish river system was investigated using radiotelemetry. Hatchery-reared 1+-year-old Atlantic salmon, Salmo salar L., smolts of equal size from two different non-native strains were radio-tagged and followed during their downstream migration through the 12-km-long reservoir. A total of 50 salmon smolts, 25 of Swedish (Atran River) and 25 of Irish (Burrishoole River) origin, were surgically implanted with miniature radiotransmitters. The tagged smolts were tracked daily over a 3-week period in May 1996. The Atran smolts initiated migration first (P < 0.001), moved faster (P < 0.01), were delayed less when passing a culvert (P < 0.001) and were more successful in moving through the reservoir than the Burrishoole smolts. The observed differences in migratory behaviour are interpreted as evidence of a genetic component influencing smolt migration.