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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Study reveals information on cutthroats



 (The Spokesman-Review)
Rich Landers The Spokesman-Review

While photo- graphic evi- dence has proved that water once flowed on Mars, the year’s most intriguing scientific news for Inland Northwest anglers has been compiled in our backyard.

Idaho Fish and Game Department fisheries biologists, with the help of volunteer fly-fishers, have been tracking cutthroat trout in the Coeur d’Alene River.

The 78 fish caught and implanted with tiny radio transmitters have been monitored for the past year, giving intimate insight into the lifecycle of the river’s cutthroats, the native neighbors we see so regularly and understand so little.

Joe Dupont, the study leader, has a CIA operative’s insight into how these fish live, spawn and die.

While they find ways to hide from anglers during the year, they could not hide from DuPont’s receiver.

When last summer’s drought nudged river water temperatures above 78 degrees, a thermal death zone for trout, “Fish tucked under cut banks, logs, rocks or whatever and just lay there,” DuPont said. The fish apparently struggled to survive as they hugged the bottom and gasped for oxygen.

“Most of the fish we saw were not actively feeding or leaving the cover,” he said, indicating the reason fishing is so poor when water temperatures soar.

More significantly, the researchers found that some of the fish found refuges of significantly cooler water in some spring-fed side channels.

“When we snorkeled one of the cooler side channels during the heat of the summer, we saw probably over 800 fish — cutthroat trout, rainbow trout and mountain whitefish — in an 80-yard length of stream,” he said.

Many of these side channels are on private property, researchers found. That’s beneficial to the fish if it prevents crowds of anglers from taking advantage of their concentration and hammering them during the stressful summer heat.

However, private property is more susceptible than the national forest to agricultural uses and development.

“We’ve long known that side channels are important for juvenile and over-wintering fish,” DuPont said. “Finding out they can also provide a cool temperature refuge during summer will only increase our efforts to help protect the floodplain in the lower river where side channels typically would be found.”

Unlike St. Joe River cutthroats, which migrate long distances to deep downstream holes for the winter, about 75 percent of the adult Coeur d’Alene cutthroats in the study generally remained within 10 miles of where they were tagged.

For example, fish tagged in Tepee Creek or the Little North Fork remained in those streams, possibly because the Coeur d’Alene drainage has more flood plains than the St. Joe, allowing fish that remain upstream to escape the ravages of high runoff.

The research eases concerns that many of the fish spared by anglers in the catch-and-release area upstream from Yellowdog Creek would migrate downstream to where they could be harvested.

However, fishing regulations are effective only if they are observed, and researchers learned that poachers are rampant in 20-mile section of the North Fork from the South Fork upstream to the Prichard area.

“Seven of our radio-tagged fish spent over a month in this stretch,” DuPont said. Five or six of them were killed by fisherman, three of which were caught illegally, he said.

“We’re not sure whether people don’t know the regulations or whether they don’t care,” DuPont said. “Either way, we can take action.”

Even though the department and area sportsmen have put up five huge signs upstream from Interstate 90 plus numerous smaller posters to detail fishing regulations, DuPont said the agency would put up even more signs.

In the North Fork’s harvest section below Yellowdog Creek, anglers can keep two fish a day from the Saturday of Memorial Day weekend through Dec. 31, but it’s illegal to kill cutthroats in the 8- to 16-inch range.

“We can increase enforcement patrols in the Prichard area, where we found a significant amount of people taking fish that were too small and people fishing out of season,” he said.

Other notable research findings include:

•Coeur d’Alene River cutthroats spawn from April through May. The April spawners area already moving down out of Tepee and Independence Creeks. The late spawners come upstream from below the South Fork where a slightly different stock of fish apparently has evolved in the last 20 years.

“As late as the ‘70s, there were no fish there,” DuPont said. “They probably came from surrounding tributaries and developed a different pattern.”

•Spawning fish spread into numerous tributaries. “That’s good,” he said. “If something bad happens in one tributary, it won’t affect all of the fish.”

Researchers hope to use this study with further research to help pinpoint habitat projects that might help improve Coeur d’Alene River cutthroat populations toward the more bountiful numbers found on the St. Joe.

“We have some big fish on the Coeur d’Alene,” DuPont said, noting that the largest cutthroat tagged during the study was 19.5 inches long. “But the numbers have been better historically.

“The Forest Service has habitat projects on a number of tributaries, but we learned that Shoshone Creek, for instance, is 4-10 degrees cooler than the main river in summer. That’s an area the Forest Service had written off because we didn’t think the habitat was that great, but now it appears to be very important.”

Anglers will be able to do their own research starting Saturday, with the opening of Idaho’s general stream fishing season.

The water levels are fairly low for this time of year and, barring a big storm, fishing should be excellent upstream of Shoshone Creek and downstream of the South Fork, DuPont said.

“The rain last weekend did bring the water levels up, but they should be back to decent levels by this weekend.”

No need to get up at dawn this time of year.

“The best fishing is when the water temperatures exceed 50 degrees, which has been occurring around noon,” said DuPont, who has been doing some preseason research sampling with a fly rod.