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Hatchery-raised steelhead trout have offspring that are good at gaining size under hatchery conditions but don’t survive as well in streams as steelhead whose parents are wild fish, new research by Oregon State University shows.
The results, published in PLOS One, suggest that it may be possible to change rearing methods to produce hatchery fish that are more like wild steelhead, which could help them survive better and also allay concerns about them mixing with wild populations, said OSU scientist Michael Blouin, who led the study.
Steelhead hatcheries provide fish for harvest and to supplement wild stocks of an iconic species that’s ecologically, culturally and recreationally significant. |
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Like salmon, steelhead (Oncorhynchus mykiss) are anadromous, meaning they travel to the ocean as “smolts” and return to their natal streams to spawn. Hatcheries raise eggs and juvenile fish for about a year and then release them to go to sea.
It is well established that hatchery fish make better brood stock than wild fish, producing more fish that return for harvest, Blouin said. On the other hand, hatchery fish produce fewer returning offspring when both spawn in the wild.
This tradeoff appears to happen because hatcheries are inadvertently favoring genes that promote growth in the hatchery environment at a cost to survival in the wild, he said. |
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