Definition of smolt in US English:



  • A young salmon (or trout) after the parr stage, when it becomes silvery and migrates to the sea for the first time.

    • ‘During our 1996 investigations, we found evidence of predation on a salmon smolt by striped bass, and we utilized available ultrasonic tags to monitor the movements of striped bass.’
    • ‘Young fish were also reared in hatchery tanks and released as smolts, the stage at which salmon head to sea before traveling to northerly feeding grounds.’
    • ‘Perhaps only 50 reach the ocean as smolts - young salmon that have taken on the characteristic silvery color - about two years later.’
    • ‘One or two years later, the smolts begin to migrate to the Pacific, where they live for one to three years before returning to the river.’
    • ‘While in freshwater, Chinook Salmon fry and smolts feed on plankton and then terrestrial and aquatic insects, amphipods and crustaceans.’


Late Middle English (originally Scots and northern English): of unknown origin; compare with smelt.