Migratory Urge and gill Na+, K+ -ATPase Activity of Hatchery Reared Atlantic Salmon Smolts from Dennys and Penobscot River Stocks, Maine and Review of Enhancement Programs
Atlantic salmon Salmo salar management is complicated by their complex anadromous life cycle and extensive marine migrations through international waters. A primary enhancement strategy is stocking the smolt life-stage, but marine mortality of smolts is high. Hatchery reared Atlantic salmon smolts p...
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DigitalCommons@UMaine
2009
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/1386 https://digitalcommons.library.umaine.edu/context/etd/article/2418/viewcontent/SpencerRC2009.pdf |
| Summary: | Atlantic salmon Salmo salar management is complicated by their complex anadromous life cycle and extensive marine migrations through international waters. A primary enhancement strategy is stocking the smolt life-stage, but marine mortality of smolts is high. Hatchery reared Atlantic salmon smolts produced from captive-reared Dennys River and sea-run Penobscot River broodstock are released into their source rivers in Maine. The adult return rate of Dennys smolts is comparatively low. This may be a function of ecological factors unique to the Dennys River and bay, or reflect poor quality of hatchery smolts produced by Dennys River stocks. The Dennys River environment compares favorably to the Penobscot River, and telemetry studies indicate in-river mortality for migrating smolts is much lower than in the Penobscot. There are ecological factors unique to Dennys Bay (Atlantic salmon aquaculture, complex geomorphology and hydrology) but the impacts of those on smolt survival are unknown. Smolt mortality is much higher in Dennys Bay than in Penobscot Bay based on telemetry studies. Broodstock genetic composition and rearing environment differ between watersheds and may affect smolt quality. Despite decades of stock transfers between watersheds, Penobscot and Dennys smolts maintain some genetic separation, and differences in stock specific traits (e.g. fecundity, morphology) have been identified in common garden studies of other Maine stocks. Genetic differences may reflect local adaptations which convey survival advantages or result from other factors. Domestication is implicated in reduced performance of salmon stocks and the captive-rearing environment of Dennys broodstock may increase domestication effects relative to anadromous Penobscot broodstock, reducing smolt quality. Diminished smolt quality may be most evident at critical life-stages such as the parr-smolt transition (PST) and seawater entry. To assess smolt quality and performance indices for these stocks during the PST, behavioral trials were conducted ... |
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