REDSIDES: THE INSIDE STORY.

Byline: Mike Stahlberg The Register-Guard

Mother Nature has yet to evolve a strain of bar-coded trout. Yet some McKenzie River fishing guides will soon be "scanning" trout, just like cashiers at a checkout stand.

But the hand-held scanning devices used by the guides are designed to detect and read tiny "transponders" surgically implanted in some wild fish, not bar codes.

It's all part of an ambitious research project undertaken by the Oregon Department of Fish and Wildlife (ODFW), with financing provided by the McKenzie River Guides Association and some of their long-time clients, and by the Oregon Wildlife Heritage Foundation.

The guides association and several area fishing clubs are also providing volunteers to help catch and/or "tag" fish. Members of those groups are also expected to do the lion's share of the monitoring and data collection.

The purpose of the project is to learn more about the health and habits of the McKenzie's native fish populations, especially the "redsides" (rainbow trout) that made the McKenzie famous among Western anglers during the first half of the 20th century.

The research, which will focus on those sections of the river where native fish must co-exist with hatchery-reared "planters," could help determine whether "bait fishing" will continue to be allowed in sections of the McKenzie.

"There is no data on the redsides, except from a 1988 creel survey," said Steve Mealey, secretary of the McKenzie River Guides, an association of fishing guides formed in 1931. "For a marvelous river like this, it seems like there ought to be some data. That's why everybody is fairly excited about this (project)."

Mealey and volunteers representing Trout Unlimited, the McKenzie Fly Fishers and the Cascade Family Fly Fishers spent a day on the river last week helping with the first phase of the project - catching and tagging wild rainbow and cutthroat trout.

ODFW biologists Jeff Ziller and Erik Moberly inserted small, glass-encased "Passive Integrated Transponders" (otherwise known as PIT tags) into a 3 millimeter incision made in the bellies of wild fish that had been caught on artificial flies, then anesthetized. After the tag was inserted, the incisions were slathered with an antiseptic salve and the fish released, apparently none the worse for wear.

"In four days, you can hardly tell the fish has had an incision on its side," Moberly said.

PIT tags are inert, glass-encased devices with internal circuits that become activated when exposed to the radio frequency emitted by the scanners.

"What happens is the scanner excites the tag electronically, and the number bounces out," Ziller said. "It's pretty cool technology."

Each tag emits a unique number, allowing researchers to keep track of fish on an individual basis.

Mealey and two other guides association officers - President Steve Schaefers and past President Aaron Helfrich - have so far been trained in the simple "micro-surgery" procedure, and will carry portable "tagging kits" in their boats so they can mark wild fish landed by their clients.

"We had a training session about a month ago, then they put all the fish we did in a tank so we could check mortality," Mealey said. "So far, they're all still alive."

The guides and the other donors put up the $4,300 used to purchase 875 tags (which cost just under $3 apiece) and five portable tag readers (at $408 each). Additional scanners have been ordered, Moberly said, and while the guides are expected to do the bulk of the data collection, members of the general public "will have an opportunity to check out a reader and collect re-capture information for us."

That process will be as simple as pushing a button on the reader while holding it close to a wild fish. If the fish carries an implanted tag, a number will appear on the reader's screen. In either case, the volunteer will record the size and species of the fish, and the location where it was caught.

About 170 wild fish have been tagged so far, Moberly said. The plan is to mark about 400 wild fish in the upper McKenzie (Blue River to Leaburg Dam) and a similar number in the section from the dam downstream to Hayden Bridge. The tags will continue to work indefinitely.

"If we tag a six-inch fish that's a year and a half old, we may continue to get data on that fish for seven years," Moberly said.

Data gathered by the project over the next several years will allow ODFW researchers to calculate the size of the native trout populations by comparing the ratio of "marked" to "unmarked" fish caught by anglers carrying the scanners. In addition, biologists will be able to learn more about the distribution and range of the fish, their rates of growth, and something about the relationship between native and hatchery trout.

By installing tag detection stations on the fish ladders at Leaburg Dam and near the mouths of key McKenzie tributary streams, biologists also hope to learn more about movements of native fish, and about the timing and location of their spawning.

The ODFW's participation in the study is not motivated entirely by curiosity.

There's also concern about the health of the native redside population.

"The more we've done this, the more we realize maybe there's not as many wild fish up here as we thought," said Ziller, who oversees the South Willamette Watershed for the ODFW.

Because the harvest of native trout has been banned on the McKenzie for several years, and because only sterile hatchery fish are released on the river (thus preventing their interbreeding with native redsides), "my assumption was ... the wild fish numbers up here, at least for rainbow, would be comparable to what we see down below (Hayden Bridge)," Ziller said. "Now, I don't know that that's the case."

Hatchery fish are not released in the McKenzie below Hayden Bridge - a section that has been managed exclusively for wild fish for about 15 years.

If the PIT tag research shows the redside population between Hayden Bridge and Forest Glen boat ramp near Blue River to be in trouble, that would likely lead to a ban on the use of bait in that section. Angling in the remainder of the McKenzie and its tributaries is restricted to artificial flies and lures.

"One thing we've always had to swallow hard on with the McKenzie is catch-and-release bait fishing," Ziller said. "If you have a high percentage of fish that you want to release, you don't have bait angling in there because the mortality rate is so high."

Ziller said he's "contemplating" proposing a bait ban for the McKenzie "no matter what we get out of the population estimate. ...

"But if I find the population of native rainbow is way down, it might quicken my thought process," he said.

"I don't want to do it if I don't have to, but we might have to do it."

CAPTION(S):

A cutthroat trout receives a PIT tag similar to those being used to monitor the population of native rainbow trout, or redsides. A biologist begins to slip a PIT tag into a cutthroat trout's stomach cavity through a small incision he made just behind one of the fish's fins. The fish will carry the inert tag for the rest of its life, providing biologists an opportunity to learn about its movements and growth rate. While cutthroat are also being tagged, the tagging project was prompted by a desire to know more about native rainbow, or redsides. Steve Mealey (left) and Jeff Ziller examine one of the rainbow trout brought to them for tagging last week. A scanner displays the unique eight-digit number associated with a PIT tag. A radio frequency transmitted by the hand-held scanner activates the PIT tags. Fishing guides and volunteer anglers will use the scanners to check the wild fish they catch for the presence of PIT tags as part of a research project