Salmon carcasses fill Oregon rivers. It’s all part of the plan

Alanna Madden

GATES, Ore. (CN) – If you see dead fish in rivers in Oregon’s Willamette Valley, don’t panic. During the month of September, the Oregon Department of Fish and Wildlife intentionally releases dead hatchery salmon into rivers and streams as part of a stream enrichment program—a process typically fueled by historic salmon runs.

According to Fish and Wildlife, thousands of adult salmon once died spawning in Oregon waterways, providing essential nutrients such as ocean-derived nitrogen. In addition to ensuring water health, dead fish also feed bears and other wildlife, and fertilize trees and vegetation along river banks.

According to the department, the run is particularly good this year because the region’s historically wet winter has provided the water levels needed to keep the fish healthy enough to travel to and from the Pacific Ocean.

However, Fish and Wildlife does not needlessly kill salmon to return nutrients. On the Santiam River in particular, the process begins and ends at the Minto Fish Collection Facility outside Gates, Oregon, where thousands of spring Chinook salmon return to their spawning home and hatchery waters. Once spawning occurs, either naturally or through incubation, all adult salmon inevitably die.

Born to be wild

Upon entering the shuttered state-owned facility, you’ll find large white plastic containers filled with large spring Chinook salmon — all cut across the belly, tails cut in half. However, the ominous litter of dead broodstock is actually a product of rebirth, as facility workers capture hatchery-born adults to collect their roe and milk for future runs.

A worker at the Minto Fish Facility outside Gates, Oregon prepares a salmon product by removing blood from a fish’s tail. (Alanna Madden/Court News)

A worker at the Minto Fish Facility outside Gates, Oregon prepares a salmon product by removing blood from a fish’s tail. (Alanna Madden/Court News)

Each female spring Chinook salmon, identified by a clipped adipose fin, carries approximately 4,500 ready-to-harvest eggs, providing hatchery storage for the following year. However, this year the hatchery expects to harvest about 2.5 million eggs, as the North Santiam stock has reached 7,200 so far. According to Fish and Wildlife Hatchery Manager Greg Grenbemer, this is the largest run since 1951 or so, when the Big Cliff and Detroit dams were installed upstream.

But before that point, there is a special process for euthanizing salmon. First, the hatchery puts the fish to sleep for a few minutes in a tank of water treated with a natural anesthetic. After that, 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 way to euthanize fish. Once the fish is ready for harvest, hatchery workers cut off the fish’s tail to remove the blood.

Oregon Fish and Wildlife Biologist Elise Kelley tosses a Spring Chinook salmon carcass into Whitewater Creek outside Gates, Oregon. (Alanna Madden/Court News)

Oregon Fish and Wildlife Biologist Elise Kelley tosses a Spring Chinook salmon carcass into Whitewater Creek outside Gates, Oregon. (Alanna Madden/Court News)

After the eggs and milk products—the male fish’s sperm—are collected, hatchery staff send each salmon to an on-site pathology lab to test for diseases that may affect the eggs. The testing process takes just 30 seconds, and it’s just as easy for the hatchery to create genetic profiles of individual fish to track them as they return from the ocean. Once approved, the hatchery fertilizes the live eggs with milk, begins a 14-month incubation journey at the Marion Forks Hatchery, and is eventually released into the wild.

According to Grenbemer, the Minto Fish Facility does not harvest Chinook salmon that pass each spring, and all wild salmon are released or transported upstream of the dams to spawn. Fish and Wildlife Assistant Fish Biologist Alex Farrand explained that the two dams do not have fish ladders. Otherwise, the only way salmon can get through is through dam turbines or spillways when reservoirs empty in winter.

As for the harvested fish, their carcasses are either donated to food banks, local tribes, or often returned to rivers with the help of Fish and Wildlife biologists like Farrand and Elise Kelley, who carry containers of fish carcasses to remote areas. Downstream from the Minto Fish Facility.

This month, Farrand and Kelley drove a collection of salmon carcasses to Whitewater Creek, about 10 minutes east of Gates. Through two separate parking lots, one near the entrance to a private road on the edge of the creek and the other about three miles downstream, biologists took turns dumping fish carcasses into the creek, most of which drifted down as if they were still alive.

The reason Farrand and Kelley are careful to drive to a remote, private area is to avoid potential interactions with recreation areas or pets. For dogs in particular, salmon is known to carry pathogens that are toxic and fatal if untreated. In addition, Farrand explained, tossing salmon carcasses upstream encourages the expansion of spawning grounds because the smell of dead fish indicates potential mating grounds for returning fish.

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