'Large wood' enhances Metolius redband habitat

Fishermen have occasionally been known to curse underwater snags when a fishing line becomes tangled on one.

However, such snags -- "large wood" to biologists -- produce benefits to the fish that are far greater than the annoyance of ripping off an incidental hook.

Scott Cotter is a fishery biologist with the U.S. Forest Service, and he's working on a project with the Sisters Ranger District to introduce even more such snags into the Metolius River.

These trees, he says, provide fish habitat and maintain the stability of the river.

He also reports that most of the fish are found in close proximity to the large wood obstructions.

Cotter doesn't make this claim by standing on the bank and guessing where the fish are. He goes right in after them.

"When snorkeling the Metolius River this summer," he said, "I can verify that most of the redbands, browns, and bull trout we counted were found close to large wood and branches, or in the seams and pockets that were created by large wood."

Historically, there were plenty of natural snags in the Metolius River. Like everything else, though, people had an effect on that natural condition.

The biologists say that much of the natural large wood was removed from the Metolius in the early 1900s in well-intentioned projects to clean up the river.

Another factor leading to the recent absence of large wood is that dead trees in and around campgrounds have been cut down to protect visiting campers and recreationalists.

As a result, the potential for natural tree falls into the river has been greatly reduced.

Cotter looks upon the stewardship of the Metolius River as his mission.

"I fly-fished the Metolius as a kid, and now I'm back to care for it as an adult," he said, "and a lot of my job centers on educating the next generation about the environmental ethics surrounding aquatic ecosystems."

Each year the Forest Service identifies dead or dying trees that pose a potential hazard to people using the National Forest. In the past such trees were often just removed.

Now, however, biologists try to find some that can be felled directly into the river and left to benefit stream function.

Such trees, Cotter said, are felled "in ways that will allow for safe boating passage, provide for trail access, provide fish habitat, and maintain stability against high flows."

When trees are felled into the river, the exact placement is determined on a case-by-case basis.

Depending on the circumstances, introduced large wood may barely encroach on the banks or project across most of the river.

When a tree fell across the river last year near the Smiling River Campground below Camp Sherman, Cotter and fellow biologist, Brad Houslet, waded right in to put some finishing touches on the natural fall.

By removing upward projecting limbs, they were able to make the area safe for boat passage and leave the tree right where it fell.

"It spans the entire river," Cotter said, "and slows down the water, providing a pool, as well as excellent cover for trout."

He added, "We snorkeled it in August and there were a number of large redband hanging out under it, in addition to dozens of young redband trout and brown trout in resting places among its branches and in the slack water behind it."

In addition to the physical benefits provided by the large wood obstructions, Cotter says that the large trees also add to the biomass of the river since they "usually remain stable for many years as they slowly break down into organic matter that can be used by stream organisms."

It's clear to the biologists that the program is working.

"The redband trout population is rapidly increasing since we started to track the spawning numbers with redd counts," said Mike Riehle, Fishery Biologist with Sisters Ranger District.

"Each year we are counting an increasing number of spawning sites, showing that the upper Metolius is really coming back from the low numbers of fish in the 1990s."

Redds are fish "nests" in the stream gravel, and the biologists keep track of them by placing a white stone near each one to show that it has been counted.

The fish counters ask that people not disturb these marker stones so that the tallies will continue to be accurate.

Riehle also pointed out that the redbands are not the only beneficiaries of the program.

"Additional wood also benefits other species of fish such as bull trout, brown trout, and Chinook."

While Chinook salmon have been absent from the Metolius for nearly 40 years, Portland General Electric is funding a study related to possible reintroduction of the species.

As part of the study, Chinook fry have been introduced into the upper Metolius Basin, and their survival rate is being monitored.