Migration and survival of Atlantic salmon Salmo salar smolts in a large natural lake.

An investigation with acoustic telemetry of the passage of Salmo salar smolts through a large natural lake found heavy mortality occurred at the river-to-lake confluences (mean 31.2% km-1 ), but was lower in the main body of the lake (mean 2.4% km-1 ). Predation was a significant pressure on emigrating smolts as tagged pike Esox lucius aggregated at river-to-lake confluences during the peak of the smolt run. Tagged smolts mainly emmigrated into the lake in the late evening after dusk, possibly as a predator-avoidance behaviour.