Riverine and early marine survival of stocked salmon smolts, <i>Salmo salar</i> L., descending the Testebo River, Sweden

Abstract

Abstract A combination of radio and acoustic telemetry was used to monitor the out‐migration of hatchery‐reared Atlantic salmon, Salmo salar L., in the River Testebo, its estuary and coastal system. As with many other Baltic rivers, the hydropower regulated River Testebo once had a self‐sustaining salmon population that is now extinct. Substantial losses of smolts in the river (48–69%) and inner part of the estuary (43–47%) were found, but after leaving the estuary, the success of post‐smolts moving out of the Bay was sufficiently high (83–89%) to conclude that habitat within the bay is not a factor limiting initial marine survival. The results suggest that hatchery‐based recovery of a wild salmon population in the river will not be successful unless other actions, such as habitat improvement, are included.