For years biologists have clashed over the role that hatcheries should play in restoring salmon.
Tribal biologists have followed the lead of Indian fisherman pushing supplementation of wild stocks of salmon with hatchery stocks. Previous research and genetic experiments have suggested releasing hatchery stock into the wild weakens the genetics of the wild stocks and reduces the overall productivity of the surviving fish.
So you had the tribal view that "a fish is a fish," versus the view that the genetic purity of the native fish evolved in its watershed made it superior. Over the last 20 years the two sides have come together a bit, still, the divide remains.
But a new study published this week in the journal Molecular Ecology shows that Nez Perce Tribe’s Johnson Creek Artificial Propagation Enhancement got the same reproductive success from hatchery-reared salmon that spawned with wild salmon as salmon left to spawn in the wild.
“The Johnson Creek research clearly demonstrates how supplementation programs can boost populations and minimize impacts to wild fish populations,” said Dave Johnson, Nez Perce Tribe Fisheries Program Manager.
The study used DNA from all returning adults collected over a 13-year period to track parents and their offspring, much as Idaho Fish and Game does in its sockeye program. It also showed biologists how successful hatchery fish were at mating in the wild when compared to wild fish.
The study showed fish taken in to the hatchery produced an average of nearly five times the number of returning adults compared to the fish that were left in the wild to spawn. Hatchery fish that spawned naturally with a wild fish had equivalent reproductive success as two wild fish, suggesting that chinook salmon reared for a single generation in the specially-designed hatchery did not reduce the fitness of wild fish.
It also showed that productivity of two hatchery fish spawning naturally was not significantly lower than for two wild fish.
The study focused on the Johnson Creek chinook salmon, who spawn in a tributary of the South Fork of the Salmon River nea Yellow Pine. It lies almost 700 miles upstream from the Pacific Ocean.
“Our results question the generalization that all hatchery fish negatively impact the fitness of wild populations,” said Maureen Hess, geneticist with the Columbia River Inter-Tribal Fish Commission and lead author on the study.
The Nez Perce Tribe began the Johnson Creek project in 1998 after salmon returns had dropped to as low as five in 1995. Today returns exceed 350 adults consistently and have reached more than 1,000 several times.
I joined Silas Whitman, now chairman of the Nez Perce Tribal Executive Committee, during a spring release of smolts in the 1990s when he was in charge of fisheries. Salmon were still in the emergency room then and he was pushing for expanding hatchery supplementation dismissing geneticist critics.
Today the tribes can point to successful programs throughout the Columbia Basin where their enhanced hatcheries and careful genetic techniques have produced success.
“The Johnson Creek study is just one example out of several supplementation programs that play a significant role in recovering Columbia Basin salmon runs," Whitman said.