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Wandering coho skew fish counts

Trinity River salmon take a wrong turn up the Rogue, eventually fouling up the tally for wild Rogue coho

Hundreds of coho salmon reared at a Northern California hatchery primarily to feed members of American Indian tribes are mysteriously migrating this fall up the Rogue River, where they mistakenly get treated as if they were threatened wild Rogue coho.

The fish, released from the Trinity River Hatchery on the lower Klamath River basin, are mistakenly counted as wild Rogue coho at Gold Ray Dam, a key counting station for monitoring the region's threatened coho. The wayward salmon also are showing up in Elk Creek, possibly even spawning with wild Rogue coho.

They accidentally pass as wild Rogue coho because the Trinity strays do not sport a clipped adipose fin ' the tiny, fleshy fin on a salmon's back near its tail ' like all Oregon coastal hatchery coho do.

There's confusion about these goofy fish and there's enough of them that it's caused some concern, said Manager Randy Robart of Cole Rivers Hatchery, where almost 800 of the strays have been counted so far this fall.

Trinity fish are marked as hatchery by a clipped portion of the bony part of the right upper jaw, called the maxillary.

The clip is small and easy to miss, even by trained salmon-handlers. The mark on the right side of the fish's face, however, goes undetected at the Gold Ray Dam fish-counting station, where only their left side is visible as they migrate upstream.

Since they have an unclipped adipose fin, they are logged as natives.

It's so easy to confuse these fish with wild fish, Robart said. How can we actually say how many wild (coho) come over Gold Ray Dam? In my mind, it's a meaningless number.

The straying apparently has gone on for years, and was first identified in late 2000 at Cole Rivers Hatchery. Hatchery workers counted 317 of the strays last year, but the numbers have almost tripled so far this year and represent almost 8 percent of the coho collected so far at Cole Rivers.

Reducing the rates of straying hatchery fish is a concern because of the potential for altering wild coho's genetic traits such as size, age, time of return to freshwater and spawning time.

But Mike Evenson, an Oregon Department of Fish and Wildlife biologist in Central Point, said he suspects few of the fish are straying to spawning grounds.

I wouldn't be a bit surprised if the vast majority of them home in on the hatchery, Evenson said. But we don't know.

Also unclear are how many of the stray Trinity coho have spawned upstream of Elk Creek Dam after being trucked there by ODFW technicians.

Crew members who trap the Elk Creek fish and haul them around the half-built dam were unaware of the straying Trinity coho until halfway through last year's coho hauling, Evenson said. Some of the strays likely passed as wild coho and were trucked upstream, he said, but there is no way to tell now.

So far this year, 20 of the Trinity coho have reached the base of Elk Creek Dam, compared to just 17 stray Rogue hatchery coho and 283 wild Rogue coho.

The Trinity coho are now killed at Elk Creek, while those found at Cole Rivers Hatchery are given to the Oregon Food Bank.

For years, California biologists knew their Trinity River coho have a higher than average stray rate, but they had no idea so many of their fish headed into the Rogue this year, said Wade Sinnen, a California state biologist who oversees Trinity's hatchery coho program.

The Rogue problems would be alleviated if the California Department of Fish and Game clipped the adipose fins of the Trinity fish, something the department has resisted in the past, Sinnen said.

Perhaps we need to consider an adipose clip, Sinnen said.

The Trinity Hatchery has released coho since the mid-1960s. The stock is a mixed breed from three Northern California streams, Sinnen said.

Hatchery workers there began clipping the coho's maxillaries in the early 1990s, and chose not to add the adipose because it seemed expensive to do for little or no benefit.

We didn't see any reason to, Sinnen said. If there's no reason to mutilate a fish more than it needs, why do it?

The Trinity River Hatchery rears an average of 500,000 yearling coho for release annually, and their only legal harvest is by American Indian tribes, mainly the Hoopa and Yurok, during fall fishing allowed by treaty, Sinnen said.

The Trinity River gets Oregon hatchery strays as well, but not nearly in the numbers shown this year of Trinity strays in the Rogue, Sinnen said.

As to why the fish are showing here en masse, Sinnen can offer only a few theories.

It's possible that the fish, which mill around with Rogue coho in the ocean, are attracted by the smell of Klamath Basin water piped from Hyatt and Howard Prairie lakes into the Rogue system, Sinnen said.

Or it might be the herd mentality of coho in the ocean as they migrate south along the Oregon coast, during which the Trinity coho must pass the Rogue mouth.

When those (Rogue) fish take a left turn to go up the Rogue, those Trinity fish go right with them, Sinnen said.

Reach reporter Mark Freeman at 776-4470, or e-mail