Maine's Experience with Captive Reared Adult Atlantic Salmon Outplants

Stocking strategies to restore endangered populations of Atlantic salmon (Salmo salar) within the Gulf of Maine DPS have used all hatchery life stages available; fry, parr, smolt, egg, and gravid adults.  Management focusing on fry stocking has not resulted in significant adult returns and natural reproduction. Stocked smolts produce large returns but the long term benefits are unknown.  Adult stocking circumvents much of the hatchery influence on mate selection and potentially results in progeny that are more likely to survive and reproduce in the wild.  However, stocking adults sacrifices numerical production advantages achieved by traditional hatchery methods.  In 2005 an adaptive management project began in selected streams in which river-specific Atlantic salmon adults, reared to maturity from large parr captured in the rivers, were stocked in the autumn.  This work has expanded to other streams and includes investigations into movements, redd construction rates, site fidelity, and vital rates. Stocked adults successfully spawned producing juvenile Atlantic salmon. From acoustic telemetry gear we learned there was high fidelity to the release location at spawning. Juvenile assessments documented that 0+ and 1+ parr densities were similar to densities in fry stocked areas.  Managers need to consider lifetime fitness in evaluating large scale gravid adult outplanting projects.