Can in-Situ Experience Compensate for Hatchery-Selection?: Enhancing Post-Stocking Survival of Juvenile Atlantic Salmon

Hatchery raised (HR) fishes commonly suffer reduced post stocking survival relative to their wild counterparts resulting from a lack of context appropriate behaviour. Such behavioural deficits are commonly attributed to hatchery selection, inadvertent selection coupled with a lack of ecologically relevant experience associated with hatchery conditions.  HR juvenile Atlantic salmon have been shown to exhibit maladaptive antipredator, foraging, and territory defence patterns following stocking into natural waterways.  ‘Life skills’ training is a commonly used approach to increase post-stocking survival but has met with limited success.  Here, we test if in situ experience can reduce the effects associated with hatchery selection.  We held wild caught vs. HR salmon originating from the same population in instream enclosures for periods of 1 week under ambient or elevated predation risk conditions and recorded antipredator, territorial and foraging response patterns. Our preliminary results confirm behavioural deficits on Day 1 (reduced antipredator response, altered foraging and territorial patterns in HR vs. wild salmon).  After 7 days in enclosures however, F1 salmon increased foraging efficiency and antipredator responses (similar to wild salmon) and defended larger territories, especially those reared under elevated risk conditions. Results are discussed in light of implications for enhancing post-stocking survival of HR fishes.