July 16, 1995

A Cutt Above The Rest

Charlie Powell Correspondent
 

Imagine this job description:

Fly-fish Idaho’s backcountry trout streams. See how many westslope cutthroat trout you can catch. After measuring, tagging, fin-clipping and releasing them, go back and see how many times a season you can catch them again.

Meager pay, but if you can do statistics, a literature review, write a thesis, and successfully defend your work, we’ll throw in a master’s degree, too. We’ll even give you the flies!

Joel Hunt, 36, a research associate in the UI’s Fish and Wildlife Resources Department laughs at the misconception of his 1990 work in streams such as the St. Joe River, Kelly Creek and Moose Creek. He is quick to set straight the sound science he and fellow graduate student Robb Keith produced after a summer of labor that involved so much fishing they got tired of it. “Our objectives were to determine the angling catchability and vulnerability of westslope cutthroat trout in North Idaho streams,” said Hunt, “and to examine fish migration in relation to seasonal changes in water temperature.” In 1969 - before catch-and-release regulations were enacted - a 10-inch cutthroat was a trophy on Kelly Creek, angler surveys show. Anglers also indicated it took an average of four hours to catch it. But once the new regulations came, the fish reached 14-inch size and larger in just four years, Hunt said. Hunt was able to verify other surveys that show cutthroats are especially susceptible to angling pressure.

Cutthroats co-evolved in relatively barren streams alongside two highly aggressive fish-eating species: bull trout and northern squawfish. According to Robert J. Behnke, Colorado State University fisheries professor, that pushed cutts into a new niche. Instead of fish, cutts evolved to eat insects, especially insects found on the surface.

While the fish-eaters can grow to double digit weights, westslope cutts rarely see three pounds, although that’s not the case for all subspecies of cutthroats. Hunt defined catchability as the maximum number of times an individual fish could be caught per season. Vulnerability was defined as the proportion of fish that could caught from a given pool. Hunt studied designated portions of North Idaho streams ranging from roadsides to remote stretches miles away from roads.

He snorkeled each stream “transect” and counted the fish, a technique that doesn’t significantly disturb fish. After resting the areas, Keith fished them, using a designated series of flies: a black Woolly Bugger, an Elk-Hair Caddis and a Renegade.

Each fish caught was measured, fin-clipped and fixed with a color-coded plastic tag behind the eye.

Later, Hunt snorkeled the same areas, counted the fish and determined what proportion had been caught before. Then the process was repeated with a different color tag. Beginning on July 12, Hunt and Keith worked until late September. “We caught 143 fish once,” explained Hunt. “But we only caught 22 of the previously caught fish again. And we only caught two fish three times. Obviously, we didn’t catch an individual fish very often.”

As time passed the number of fish Hunt tagged increased, but the number of tagged fish in each pool stayed low. “Once they’d been caught, the fish moved out of the study area,” he said. ” This is unlike studies with Yellowstone cutts that showed an individual could be caught up to 10 times a season.”

Snorkeling above and below the study areas showed few of the tagged fish there either. Half went upstream, half went downstream, Hunt said.

Where the other 75 to 90 percent went awaits another study - one that should be done soon, said Hunt.

“Maybe after these fish are hooked and released, a number head into a catch-and-keep area defeating the purpose of catch-and-release as a conservation tool, he said.”

Hooking and handling mortality did not affect the study, Hunt said, noting it is well documented where fish will settle when they die and how to find them. Hunt and Keith said they found one dead cutthroat all summer. Hunt’s vulnerability studies on one cutthroat stream showed that when they first fished a road-accessible pool, 40 to 94 percent of the fish could be caught.

As the season continued, the fish became conditioned, even refractory, to the pressure. By late season in the same pools, Hunt and Keith could only catch from 10 to 50 percent of the fish.

Anglers surveyed that summer in roaded stretches of the streams showed roughly nine times more angling pressure on roaded stretches compared with remote unroaded stretches.

Interestingly, fish in remote access areas up to 8 miles from a road, behaved statistically the same as their roadside counterparts in both early and late season vulnerability.

Hunt sought to answer theories that the drop in vulnerability is a function of nutrition or seasonal variation. He set up two identical hatchery raceways, each of which was stocked with 100 cutthroats. The fish were fed the same, but one raceway was fished once a week for nine weeks. The other was left alone for nine weeks.

The raceways had identical early and late season vulnerability, mirroring that seen in the field. In other words, the fish were easier to catch when the fishing started before gradually becoming more “educated” to the ways of anglers.

Some sportsmen are urging Idaho Fish and Game Department to open streams to catch-and-release trout fishing during winter.

Considering what Hunt saw in his studies with seasonal migrations, he said a winter trout fishing season in Idaho streams could be devastating to cutthroats.

“These fish will migrate great distances, up to 150 kilometers, and congregate for the winter,” he said. “A pool may hold a thousand fish and the rest of the stream is barren for 20 miles. If that pool is accessible, the whole pool can be wiped out with little chance for recovery.”

Hunt suggests anglers look at the bigger picture. The westslope cutthroat trout originally ranged across much of the West. Today the species inhabits only a small fraction of that range.

Westslope cutthroats are being extirpated by a diminishing gene pool, habitat degradation, competition with introduced species, and continued exploitation of their willingness to strike a lure, fly or baited hook.


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