WENATCHEE — Fishermen looking to reel in a steelhead or fall chinook this month may have gotten a surprise on the end of their line, and one they’re allowed to keep — the coho.

Just 15 years after the Yakama Nation started mass-producing coho in hatcheries and releasing them from ponds along the Wenatchee and Methow rivers, more of the late-spawning salmon are in our rivers and streams than we’ve seen in at least 78 years.

As of Sunday, 28,662 adult coho swam up the fish ladders at Rock Island Dam, nearly a third more than the last big run in 2009.

If you count both adults and jacks — those not-quite-mature coho that return a year early — we’ve already seen 29,349 coho pass the dam this fall.

And they’re still coming.

Tom Scribner, a biologist who started the coho reintroduction program for the Yakamas in 1996, estimates between 30,000 and 40,000 coho will come over the dam before the run is over. The year he started, coho were all but extinct in the upper Columbia River. None made it to Rock Island that year.

“Every year when we break a record it blows me away,” he said last week. “In 2009, when we had almost 20,000 (adults at Rock Island), that was off the map. ... This (year’s run)is beyond my wildest dreams.”

As a result, on Oct. 5, the state Department of Fish and Wildlife opened the first coho fishing season on the Wenatchee and Methow rivers in at least 30 years. Jeff Korth, the agency’s regional fish manager in Ephrata, said he couldn’t find any record at all of a coho season on those rivers, and believes it’s been 40 or 50 years since one anyone has fished these two major tributaries for the late-run salmon.

There was a small coho season on the Icicle River in 2009.

But, Korth said, this season was such a surprise, many of the fishermen who caught them were actually targeting steelhead. The coho season ended Monday.

Except for chinook, coho was once the most abundant species of salmon in the Wenatchee and Methow rivers, Scribner said.

Cody Kamphaus, Yakama Nation fish biologist who has worked to recover coho for the past 12 years, said more and more North Central Washington fishermen are beginning to know about coho, and he’s talked to several who came out specifically to catch one this year. “They’re a good fighting fish, about the same size as a steelhead,” he said.

Coho return to fresh water as three-year-old fish, Kamphaus said. When they leave the ocean, they’re mostly silver with a dark blue or olive green back. By the time they make it to the Wenatchee, males have turned deep red on their sides, and developed a hump on their back and a hook on their nose. Females have changed to a lighter red or purple color on their sides.

Kamphaus said they can be two feet long, but generally don’t weigh more than 10 to 12 pounds in these waters, as they’ve lost much of their body weight in the long swim upstream.

Biologists agree that over-fishing is the main reason they stopped returning to their once-prolific spawning beds in the upper Columbia River tributaries. Scribner said unscreened irrigation canals also played a part in their demise.

He said that by the early 1900s, they had mostly disappeared, so hydroelectric dams weren’t to blame. Another effort to restore coho runs in the 1960s and 1970s failed, Scribner said.

So when the Yakamas started its coho reintroduction program in 1996, Scribner worried about using a broodstock from an area near the Bonneville Dam because these coho never had to swim as far, or pass as many dams, as their offspring would.

“I thought it would happen,” he said of their recovery, “but not as fast as it’s happened. But I knew that coho was a resilient species of salmon.”

Scribner said favorable ocean conditions have helped. In addition, they’re not subject to fishing on the lower river, so more coho make it back. “But the biggest thing is the hard work that my staff does,” he said.

Coho were already so close to extinction in this region that they were never listed as threatened or endangered. Scribner said that, too, has helped in their recovery because the tribe has more options for using hatchery fish in the effort to reestablish them. “They don’t fall under the tight guidelines that the Endangered Species Act sets out, and that allows us more freedom to reestablish them,” he said.

He said while he’s pleased with the results, the coho recovery program is far from complete.

Today, about 95 percent of the returning coho are hatchery-raised fish. The Yakama Nation’s goal now is to develop a local broodstock that has proven its ability to return and spawn in the upper tributaries. Those fish can then be left to spawn naturally.

Scribner said tribal programs have also reintroduced coho in the Yakima and Klickitat rivers. “All of the coho production above Bonneville is tribal. There wouldn’t be any coho up there if it weren’t for tribal programs,” he said.

In the bigger picture, he said, coho not only offer more fishing opportunities, but also bring more diversity to North Central Washington rivers and streams.

“They obviously provide a benefit by bringing in marine-driven nutrients. They’re the last species of salmon (to spawn in the fall), so they provide an important niche within the ecosystem,” he said.

K.C. Mehaffey: 997-2512

mehaffey@wenatcheeworld.com