GATES, Ore. (CN) — If you see dead fish in the rivers of Oregon’s Willamette Valley, don’t panic. Throughout September, the Oregon Department of Fish and Wildlife intentionally dumps dead hatchery salmon back into rivers and streams as part of its stream enrichment program — a process typically performed in historic salmon runs.
According to Fish and Wildlife, thousands of adult salmon once spawned and died in Oregon’s waterways, providing essential nutrients like nitrogen from the ocean. But in addition to improving water health, the dead fish also help feed bears and other wildlife while fertilizing trees and vegetation along river banks.
This year’s run is particularly good, according to the department, as the region’s historically wet winter provided much-needed water levels to keep the fish healthy for their voyages to and from the Pacific.
However, Fish and Wildlife does not kill salmon unnecessarily to give back nutrients. The process on the Santiam River in particular actually begins and ends with the Minto Fish Collection Facility outside of Gates, Oregon, where thousands of spring Chinook salmon return home to the breeding waters to spawn. Once spawning occurs, either naturally or through the hatchery, all adult salmon inevitably die.
Born to be Wild
Upon entering the gated government compound, you’ll find large white plastic containers filled with large spring Chinook salmon – all cut along the belly with their tails partially cut off. However, the ominous container of dead broodstock is actually the product of rebirth, as the facility’s staff capture adults born in the hatchery to collect their roe and milk for future runs.
Each female spring Chinook salmon, identified by a clipped adipose fin, carries around 4,500 eggs ready for harvest, securing breeding stock for the coming year. This year, however, the hatchery expects to harvest around 2.5 million eggs as the stock of North Santiago stocks has reached 7,200 so far. According to Fish and Wildlife Hatchery manager Greg Grenbemer, this is the largest run to date since 1951 or since the construction of the Big Cliff and Detroit Dams upstream.
But even before that, there is a special procedure to euthanize the salmon. First, the fish are channeled from the hatchery into a water tank that has been treated with a natural anesthetic that will euthanize the fish within minutes. Afterward, a hatchery employee places each fish in a “knocker” — a device that delivers a fatal blow to the head, which Grenbemer describes as the most humane method of euthanizing fish. Once the fish are ready to be harvested, hatchery staff cut open the fish’s tail to drain blood.
After collecting eggs and milk — semen from male fish — hatchery staff send each salmon to the on-site pathology lab to be tested for diseases that could be affecting the eggs. The testing process only takes about 30 seconds, and it’s just as easy for the hatchery to create genetic profiles of individual fish to track them as they make their way back from the sea. Once approved, the hatchery inseminates viable eggs with milk, begins a 14-month journey of incubation at the Marion Forks Hatchery, and finally release into the wild.
According to Grenbemer, the Minto Fish Facility does not harvest Chinook salmon every spring that passes through, and all wild salmon are released or transported upstream of the levees to spawn. The practice is necessary, explained Assistant District Fish and Wildlife fish biologist Alex Farrand, because the two dams lack fish ladders. Otherwise salmon can only pass through dam turbines or overflows when the reservoirs empty in winter.
Harvested fish are either donated to food banks or local tribes, or returned to streams, most often with the help of fish and wildlife biologists like Farrand and Elise Kelley, who drive the containers of fish carcasses to remote areas downstream of the Minto Fish Facility.
This month, Farrand and Kelley drove a load of salmon carcasses to Whitewater Creek, about 10 minutes east of Gates. At two separate stops, one near the entrance to a private road on the creek and another about three miles downstream, the biologists took turns tossing fish carcasses into the creek, most floating downward as if alive.
The reason Farrand and Kelley are careful to drive on secluded, private land is to avoid potential interactions with recreational areas or pets. For dogs in particular, salmon are known to carry pathogens that are toxic and even deadly if left untreated. Additionally, Farrand explained that tossing salmon carcasses upstream encourages the spread of spawning grounds, as the smell of dead fish signals potential mating grounds for returning fish.