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Catchment-wide survival of wild- and hatchery-reared Atlantic salmon smolts in a changing system

Daniel S. Stich·Michael M. Bailey·Christopher M. Holbrook·Michael T. Kinnison·Joseph D. Zydlewski
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Abstract

We developed a hierarchical multistate model to estimate survival of Atlantic salmon ( Salmo salar ) smolts in the Penobscot River, USA, over a decade during which two mainstem dams were removed from the catchment. We investigated effects of ( i ) environmental factors, ( ii ) rearing history, and ( iii ) management actions, including dam removal, turbine shutdown, and installation of new powerhouses. Mean ± SD smolt survival per kilometre was higher through free-flowing reaches of the catchment (0.995 ± 0.004·km −1 ) than through reaches containing dams that remain in the system (0.970 ± 0.019·km −1 ). We observed maximum survival between 12 and 17 °C and at intermediate discharges (1200 m 3 ·s −1 ). Smolt survival increased concurrent with dam removal and decreased following increases in hydropower generation. The greatest increase in smolt survival followed seasonal turbine shutdowns at a dam located on the largest tributary to the Penobscot River, while other shutdowns had little influence. Our model provides a useful tool for assessing changes to survival of migratory species and will be useful for informing stocking plans to maximize numbers of smolts leaving coastal systems.

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Canadian Journal of Fisheries and Aquatic SciencesArticle

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Daniel S. Stich, Michael M. Bailey, Christopher M. Holbrook, Michael T. Kinnison, Joseph D. Zydlewski. 2015. Catchment-wide survival of wild- and hatchery-reared Atlantic salmon smolts in a changing system. https://doi.org/10.1139/cjfas-2014-0573

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