More Data Shows Hatchery Steelhead
by Bill Rudolph
A years-long study of hatchery and wild steelhead in Oregon's Hood River has found even more startling results than researchers announced two years ago, when they found returning hatchery fish significantly underperformed wild fish when spawning in the wild.
In a 2007 article in Science, they estimated that reproductive fitness was reduced by about 40 percent per generation for two generations of steelhead that spawned in the wild after beginning life at the Hood River hatchery facility.
The latest work from Oregon State University researcher Michael Blouin found that a fish born in the wild as the offspring of two hatchery-reared steelhead averaged only 37 percent of the reproductive fitness of a fish with two wild parents, and 87 percent of the fitness if one parent was wild and one was from a hatchery.
"The message should be clear," the researchers wrote in their report's conclusion. "Captive breeding for reintroduction or supplementation can have a serious, long-term downside in some taxa, and so should not be considered as a panacea for the recovery of all endangered populations."
This research, published in Biology Letters, was supported by grants from BPA and the Oregon Department of Fish and Wildlife. Scientists have been able to genetically "fingerprint" three generations of returning fish to determine who their parents were, and whether they were wild or hatchery fish.
The OSU results may rouse supporters of supplementation, mainly tribes, who point to increasing fall chinook numbers in the Snake River and spring chinook in the Yakima and other Northwest rivers as success stories for using hatchery-raised fish to boost natural populations.
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