Wild male Coho salmon (picture above) reproduce better than males released from hatcheries. (Image credit: Bureau of Land Management Oregon and Washington)
Hatchery salmons are often introduced into rivers to support wild populations, which are in a state of decline. Yet hatchery males have lower reproductive success than wild ones, according to a study of 196 Coho salmons (Oncorhynchus kisutch).
When occupying the same position in the spawning hierarchy, hatchery males have only 55 to 84 per cent the paternity of wild males. The authors believe “differences in breeding success between wild and hatchery fish could have important management consequences” as hatchery fish will have lower fitness than wild fish in mixed populations.
The researchers believe this could partly explain why previous studies have failed to show an improvement of fish stocks when wild populations are supplemented with hatchery salmon.
Original research paper published in Royal Society Open Science on August 11, 2015.
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