Landlocked Atlantic salmon: movements to sea by a putative freshwater life history form

摘要

Certain populations of Atlantic salmon (Salmo salar) have become landlocked, and live their entire life history out in freshwater. On the Magaguadavic River, New Brunswick, Canada, hatchery and wild origin landlocked salmon were detected moving downstream towards the ocean, and subsequently back upstream in the river. High levels of strontium, indicative of ocean residence, were found in the scales of these fish. In 2002 and 2003, 23 and 13 landlocked salmon, respectively, from this river were fittedwith acoustic tags, and their movements in the lower river and adjacent coastal area were monitored. Some fish covered long distances, eventually moving beyond our tracking array. Others remained in coastal waters in close proximity to the river and itsestuary. Two fish that returned early to the river were infested with sea lice, and were detected in areas close to commercial salmon farms.