Coho are the last of the local salmon to spawn, providing valuable nutrients for other organisms over the winter.
Gone from the Methow for almost 100 years, the prized species is starting to rebound
By Marcy Stamper
Over the past month and a half, 941 adult coho salmon have been weighed and measured, had their fins clipped for genetic testing, and had their eggs fertilized in buckets to produce 1 million smolts for the next generation.
The fertilized eggs will spend a few months in the incubation stacks and will hatch in February.
It took five all-day sessions for a dozen biologists and staff with the Yakama Nation Fisheries and the Winthrop National Fish Hatchery to complete the coho spawning for the year for the next phase of the Yakamas’ Mid-Columbia Coho Reintroduction Program.
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.) But because coho were extirpated from the Mid- and Upper-Columbia and tributaries in the Methow Valley about 100 years ago — a result of overfishing, hydropower dams and habitat loss — the Yakama project had no native coho to start with, said fisheries biologist Rick Alford.
Before the 20th century, between 120,000 and 165,000 coho returned to the Mid-Columbia basin every year. Traditional coho habitat included the Yakima, Wenatchee and Entiat rivers, and some 30,000 coho reached the Methow annually, according to the Columbia River Inter-Tribal Fish Commission. But in 1938, the first year after Bonneville Dam was constructed, the coho count at the dam plummeted to 15,000.
Bob Gerwig, assistant manager of the Winthrop National Fish Hatchery, prepares to fertilize eggs with milt from a male coho. Each female has one primary male and one secondary male to ensure successful fertilization.
Unlike steelhead and spring Chinook, which are listed as endangered, coho were totally gone from the Upper Columbia, so they didn’t even qualify for that protection. “There was no broodstock to start the program, because there were no coho left,” said Alford. “Endemic stocks were gone — those genetics don’t exist anymore.”
Gradual progress
Since the coho reintroduction program began in 1995, the population is gradually being reestablished, starting with coho releases at the Winthrop National Fish Hatchery and in the Wenatchee basin. Yakama biologists decided to focus releases on the Wenatchee basin in the early years to give the fish an advantage so they wouldn’t have to migrate so far, said Alford.
As more fish returned, the biologists began releasing more coho in the Methow. They started at the Winthrop hatchery and then expanded, adding the Twisp River, Gold Creek and Wolf Creek, releasing a total of 500,000 coho annually, said Alford.
That approach has been fruitful — for the past 10 years, almost all the juveniles released in Methow River tributaries have come from parents that returned to the Methow to spawn, he said.
Next year, coho territory will expand even further, with releases at two new acclimation sites in Early Winters Creek and the Chewuch River near Eightmile. Ultimately, the biologists plan on releasing the fish at up to 10 sites, said Alford.
Casey Heemsah, a fisheries technician with Yakama Nation Fisheries, prepares female coho in the hatchery for removal of their eggs.
Coho returns have been promising over the past decade. This year, fisheries technicians with the Yakama project collected 1,207 coho at Wells Dam for spawning, and another 3,800 crossed Wells on their own and will spawn naturally, said Alford. That’s the most coho they’ve collected since the project began.
Indeed, hundreds of spawning coho have been observed in local rivers, particularly in side channels, said Kraig Mott, a fisheries biologist with the program.
Twice as many fish
This year’s coho collection marked a significant milestone, the completion of the first phase of the program — re-establishing a broodstock. Now they’re doubling that. “We’ve collected adults for a 1-million smolt release in 2019,” said Alford. “This is more than 20 years in the making.”
While coho are imprinted to travel a certain distance, returns in the early years of the program were especially low because the fish have to swim 800 miles — past nine dams — to get to Pateros, said Alford.
Since the reintroduction project was launched, the highest coho run occurred in 2014, with more than 10,000 coming over Wells. That was one of two years with enough coho to open a fishing season. This year saw the fourth-largest return since the program began, said Alford.
Coho have a shorter life-cycle than steelhead or spring Chinook. They mature over one-and-a-half years and then head to the ocean, returning at age 3 to spawn, said Alford. But that puts them at a disadvantage. “Natural occurrences can hit coho hard — they have less plasticity to rebound than other species,” he said.
This isn’t the first effort to restore coho to their former habitat. A program in the mid-1900s incubated coho in the Mid-Columbia, but the fish, which typically spawn in tributaries, were released directly into the mainstem of the Columbia River and few returned to spawn.
The spawning process
Coho are laid out in a spawning rack, where they’re bled to prevent excess organic matter from getting into the eggs during fertilization.
Technicians collecting fish at Wells Dam differentiate between females, whose bellies are swollen with 2,700 eggs, and males, which have a longer kipe (nose), and aim for an even distribution, said Mott.
At the hatchery, biologists rub the abdomen of the females to check for softness that indicates they’re ready to drop their eggs. They also squeeze the males to see if they’re ready to eject their milt, which contains the sperm. The eggs and sperm are combined in buckets with a saline solution to ensure complete fertilization.
During the spawning, researchers gather all kinds of information about the fish, whose every movement is tracked throughout their lifetime. Biologists know how long the coho spent at the hatchery, where they were reared and released, how long they spent in the ocean, and when they swam through the Columbia River dams on their upstream migration, said Mott.
To measure egg production, technicians painstakingly count out 100 eggs from every 10th female and weigh them. That lets them extrapolate the total number of eggs and to estimate fecundity.
Fisheries biologist Kraig Mott takes genetic samples and collects data for sex, age and origin (natural vs. hatchery).
Fish scales are similar to tree rings and can be read for information about growth. The biologists also send a fin clip from every fish to a genetics lab to assess adaptation from a hatchery stock to wild stock over time.
Mott and his colleague Martin Novak have been conducting spawning-ground surveys of all Methow subbasins — by raft, pontoon, and on foot. A couple of weeks ago they walked 7 miles through the shallow bed of the Twisp River, counting redds and measuring spawning adults with a ruler.
In the recently restored 1890s side channel to the Methow River near Twisp, Mott and Novak found 75 coho redds and 200 spawning adults. Coho started using the calm, shallow channel almost immediately after it was completed three years ago. The fish like the consistent, year-round temperature from the groundwater that infiltrates the channel, said Mott.
Coho have been swimming further and further upstream in their quest for high-quality spawning grounds, said Mott. They’ve spotted coho near the Weeman Bridge near Mazama, some 10 miles above the Winthrop release sites.
Coho are not only prized for eating, but they also provide benefits to the entire ecosystem through increased biodiversity and the addition of important nutrients from the ocean. The program also contributes to the Yakamas’ goal of reestablishing a historic coho fishery, said Alford.
Coho spawn later in the year than other salmon in the Methow basin, reaching their spawning grounds in October and November. That’s especially helpful because it deposits nutrients in the river that help sustain organisms over the winter.
The Yakama program includes partnerships with the federal government, the state and with private landowners, who’ve provided most of the acclimation ponds. It’s funded by the Bonneville Power Administration and the Chelan and Grant county public utility districts.
