GATES, Ore. (CN) — If you see dead fish in rivers in Oregon’s Willamette Valley, don’t panic. Throughout September, the Oregon Department of Fish and Wildlife intentionally releases dead hatchery salmon into rivers and streams as part of its stream enrichment program – a process usually provided by historic salmon runs.
According to Fish and Wildlife, thousands of adult salmon have spawned and died in Oregon’s waterways, providing essential nutrients such as nitrogen from the ocean. But in addition to supplementing water health, dead fish also help feed bears and other wildlife while fertilizing trees and vegetation along stream banks.
The race is particularly good this year, according to the department, as the region’s historically wet winter provided much-needed water levels to keep the fish healthy for their journeys to and from the Pacific Ocean.
However, Fish and Wildlife does not needlessly kill salmon to restore 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 hatchery waters to spawn. Once spawning occurs, whether natural or in hatcheries, all adult salmon inevitably die.
born to be wild
Upon entering the gated government facility, you’ll find large white plastic bins full of large spring chinook salmon – all sliced on the belly with their tails partially cut off. However, the ominous trash of dead broodstock is actually the product of a rebirth, as facility staff catch hatchery-born adults to collect their eggs and milt for future races.
Identified by a severed adipose fin, each female Spring Chinook Salmon carries approximately 4,500 eggs ready for harvest, ensuring hatchery stock for the coming year. This year, however, the hatchery expects to harvest around 2.5 million eggs, as North Santiam’s stock has reached 7,200 so far. Fish and wildlife hatchery manager Greg Grenbemer said it was the largest run since 1951, or since the Big Cliff and Detroit dams were installed upstream.
But even before that point, there is a special process for euthanizing salmon. First, the hatchery brings the fish into a tank of water treated with a natural anesthetic that puts the fish to sleep within minutes. Afterwards, a hatchery worker places each fish in a “thumper” – a device that delivers a lethal blow to the head, which Grenbemer describes as the most humane method of euthanizing fish. Once the fish are ready to be harvested, hatchery workers slice the tail off the fish to drain the blood.
After collecting the eggs and milt – the sperm from the male fish – hatchery workers send each salmon to its on-site pathology lab to test for diseases that may affect 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 when they return from the ocean. Upon approval, the hatchery inseminates viable eggs with milt, beginning a 14-month incubation journey at Marion Forks Hatchery and eventual release into the wild.
According to Grenbemer, the Minto fishing facility does not harvest the chinook salmon passing through it every spring, and all wild salmon are released or transported upstream of the dams to spawn. Practice is necessary, said Alex Farrand, assistant district fish biologist for fish and wildlife, because both dams do not have fish ladders. Otherwise, the salmon can only pass through the turbines of the dams or the weirs when the reservoirs empty in winter.
As for harvested fish, their bodies are either donated to food banks, local tribes or, more often than not, returned to the waterways with the help of Fish and Wildlife biologists like Farrand and Elise Kelley. , which lead the bins of fish carcasses to remote areas. downstream of the Minto fishing facility.
This month, Farrand and Kelley drove a batch of salmon carcasses to Whitewater Creek, about 10 minutes east of Gates. Through two separate stops, one near the entrance to a private road near the creek and the other about five kilometers downstream, biologists took turns tossing fish bodies into the creek, most drifting as if they were alive.
The reason Farrand and Kelley are careful about traveling to remote private land is to avoid potential interactions with recreational areas or pets. For dogs, in particular, salmon is known to carry pathogens that are toxic and even deadly if left untreated. Additionally, Farrand explained that dumping salmon carcasses upstream encourages the expansion of spawning grounds, as the smell of dead fish signals potential mating grounds for returning fish.