Salmon carcasses fill Oregon rivers. It’s all part of the plan
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 is intentionally throwing dead hatchery salmon back into rivers and streams as part of its stream enrichment program — a process typically provided by historic salmon runs.
According to Fish and Wildlife, thousands of adult salmon once spawned and died in Oregon waterways, supplying essential nutrients such as nitrogen acquired from the ocean. But besides supplementing water health, the dead fish also help feed bears and other wild animals while fertilizing trees and vegetation along stream banks.
The run is particularly good this year, according to the department, as the region’s historically wet winter provided much needed water levels to keep fish healthy for their journeys to and from the Pacific Ocean.
However, Fish and Wildlife is not needlessly killing salmon for the sake of returning 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 are returning home to the hatchery waters to spawn. Once spawning takes place, whether it be natural or through the hatchery, all adult salmon inevitably die.
Born to be wild
Upon entering the gated government facility, you’ll find large white plastic bins filled with large spring Chinook salmon — all sliced down the abdomen with their tails sliced partway off. However, the ominous bin of dead broodstock is actually the product of rebirth, as staff at the facility are catching hatchery-born adults to collect their roe and milt for future runs.
Identified by a clipped adipose fin, each female spring Chinook salmon carries around 4,500 eggs ready for harvest, ensuring hatchery stock for the upcoming year. This year, however, the hatchery expects to harvest around 2.5 million eggs, as the run of North Santiam stock has reached 7,200 so far. According to Fish and Wildlife Hatchery Manager Greg Grenbemer, it’s the largest run yet since 1951, or since the installment of the Big Cliff and Detroit dams upstream.
But even before that point, there’s a special process to euthanize the salmon. First, the hatchery funnels fish into a water tank treated with a natural anesthetic that puts fish to sleep within a few minutes. Thereafter, a hatchery employee places each fish into a “thumper” — a device that delivers a lethal blow to the head, which Grenbemer describes as the most humane method of euthanizing fish. Once fish are ready for harvest, hatchery employees slice the fish’s tail to drain out blood.
After collecting eggs and milt — semen of male fish — hatchery employees send each salmon to its on-site pathology lab to test for illnesses that may affect 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 journey back from the ocean. Upon approval, the hatchery inseminates viable eggs with milt, beginning a 14-month journey of incubation at Marion Forks Hatchery and eventual release into the wild.
According to Grenbemer, the Minto Fish Facility does not harvest every spring Chinook salmon that passes through, and all wild salmon are released or transported upstream of the dams to spawn. The practice is necessary, explained Fish and Wildlife Assistant District Fish Biologist Alex Farrand, as the two dams do not have fish ladders. Otherwise, the only way salmon can pass by is through dam turbines or spillways when the reservoirs empty in the winter.
As for harvested fish, their bodies are either donated to food banks, local tribes or, most often, returned to streams with the help of Fish and Wildlife biologists like Farrand and Elise Kelley, who drive the bins of fish carcasses to remote areas up and downstream from the Minto Fish Facility.
This month, Farrand and Kelley drove a batch of salmon carcasses up to Whitewater Creek, about 10 minutes east of Gates. Through two separate stops, one near the entrance of a private road by the creek and another about three miles downstream, the biologists took turns tossing fish bodies out into the creek, with most drifting down as though they were alive.
The reason Farrand and Kelley take care to drive to remote, private land is to avoid potential interactions with recreational areas or pets. For dogs, especially, salmon are known to carry pathogens that are toxic and even lethal if left untreated. Additionally, Farrand explained that tossing salmon carcasses upstream encourages spawning ground expansion, as the scent of dead fish signals potential mating grounds for returning fish.