Coho salmon swam upstream last week below the Spring Creek footbridge in Winthrop.
In the complex world of salmon recovery, coho are something of a success story right now.
This fall, a record 25,000 coho salmon passed over Wells Dam, the highest number since records have been kept, said Rick Alford, supervisory biologist for the Yakama Nation Mid-Columbia Coho Reintroduction Program. The previous record was set in 2019, when only about 12,000 came back over Wells.
Coho spawn from mid-October to early December. This year, the easiest place to see coho spawning is in the shallower pools in the Methow River below the Spring Creek Bridge in Winthrop.
Coho were once the most abundant anadromous species in the Methow basin. (Anadromous fish spend part of their life in freshwater and part in the ocean.) Locally adapted, or native, stocks were extirpated in the early 20th century due to overfishing, habitat loss, past hatchery practices, and the construction of dams. They were completely gone from the Mid- and Upper Columbia and from tributaries in the Methow Valley, Alford said.
There were no native coho in 1996 when the Yakama project started, with a goal of re-establishing the lost, naturally spawning populations. Because there are no longer native fish here, coho are not considered “endangered” like spring Chinook and steelhead are.
“It’s exciting stuff to see fish coming back in these numbers,” Alford said. All the returning coho are from parents that returned to spawn in the Methow, Chewuch and Twisp rivers, Alford said.
Biologists collect broodstock at Wells in October – about 700 fish in all, half female and half male – and spawn them at the Winthrop National Fish Hatchery. In addition, the remainder — thousands of returning adults — are allowed to pass through to reach the spawning grounds.
The hatchery keeps enough fish for releases from the hatchery and for two acclimation ponds in the upper Methow. The remainder are shipped to Lower Columbia River hatcheries (a small contingent goes to the Wells Fish Hatchery) to be reared to the pre-smolt stage at 1 1/2 years old. They’re then transported back to the Methow and put into acclimation ponds for release.
Since 2019, the Yakama coho project has released 1 million smolts each year, twice as many as in previous years, to initiate natural production in the Twisp, Chewuch and upper Methow rivers.
Predictable life cycle
Coho have a shorter – and more predictable – life cycle than steelhead or spring Chinook. They leave as juveniles at 1 1/2 years and mature in the ocean, returning at age 3 the following fall to spawn, Alford said. Adults weigh 4 to 8 pounds.
Because spring Chinook return to the Columbia River in the spring, they’re especially susceptible to predation by sea lions. But the sea lions have moved on by the time the coho come through in the fall.
Since coho were extirpated from this area, there’s no historic knowledge about where they spawned. By returning to certain spots in the Methow, Chewuch and Twisp rivers, the fish are teaching the biologists.
“What’s exciting about the program now is that in the years of broodstock development, Lower Columbia stocks have adapted. Now we have our own Upper Columbia–adapted hatchery fish,” Alford said. “We’re jump-starting the natural production so there are enough fish to return as adults and to spawn in the river, to complete the life cycle again.”
The high coho returns also benefit other fish and aquatic organisms. Since coho are the last salmon to spawn, as their carcasses decompose over the winter and into the spring they generate important nutrients from the ocean to support zooplankton, insects and other salmon, Alford said. “Returning salmon are incredibly important for the food base,” he said.
“Still, it’s wise to be cautiously optimistic. A lot of things can happen. As we know, our environment is changing rapidly,” Alford said.
The Yakama project’s success relies on partnerships with federal, state and local agencies, and on support from private landowners, since most acclimation ponds are on private property. The program promotes tribal fisheries and tribal salmon-management goals.
