Kokanee loving their new gravel at Lake Pend Oreille

COEUR d'ALENE - When biologists implemented a project this summer to enhance kokanee spawning habitat in Lake Pend Oreille by placing gravel on the shoreline, they didn't know for sure whether it would be successful.

The spawning beds looked good to the biologists, but the real test was whether or not the kokanee would find them suitable. After the first spawning season, the jury of kokanee is in, and it looks like the new beds meet their approval.

Andy Dux, principal research biologist with the Idaho Department of Fish and Game, reported that thousands of kokanee were observed with an underwater camera actively spawning on the new gravel.

"Kokanee were packed onto the beds and distributed fairly evenly where the gravel was placed," Dux said. "And, few Kokanee were observed beyond the extent of the new gravel."

The project was the result of more than 20 years of research to understand the spawning requirements of kokanee in Lake Pend Oreille.

Every fall, kokanee bury their eggs in the gravels around the shoreline of the lake.

The eggs stay buried throughout the winter, until the fry (young kokanee) hatch out the following spring.

Since the mid-1990s, the elevation of the lake was held higher in the winter in an effort to keep some of the best spawning gravel underwater.

Though recent research hasn't demonstrated a significant benefit from the higher winter lake levels, it has shown that areas in the southern end of the lake tend to offer the best conditions for kokanee egg incubation.

However, some of those areas are unusable for spawning because the lake bottom is mostly made up of larger rocks and lacks small gravels.

In a project funded by the Bonneville Power Administration, Dux contracted with West Co., of Airway Heights, to place nearly 1,300 cubic yards of gravel along 300 yards of shoreline located near the Farragut State Park boat ramp.

The idea was to locate the beds in water ranging from 20-60 feet of water so they would be unaffected by winter lake level fluctuations.

According to Dux, a big challenge was to cover the target area evenly with four to six inches of gravel, as opposed to having a few big mounds here and there.

"The contractors developed a pretty slick technique using a belly dump trailer mounted on an open-centered barge," Dux said.

Using a tug boat to push the barge, the contractors were able to adjust the speed to apply the right amount of gravel.

"When we dove on the site, it was amazing how evenly the gravel coated the bottom," Dux said.

The big question was whether kokanee would find the new gravel right away and use it for spawning this fall.

"It looked great to us," Dux said. "But what looks like good spawning habitat to people may not look good to a fish."

Dux and his crew eagerly awaited the spawning season, and in early December, they weren't disappointed.

Using an underwater video camera, they were delighted to see kokanee spawning by the thousands.

"We were optimistic about the project, buy I have to say that what we saw exceeded our expectations," Dux said.

Not only were there a lot of kokanee, but they were spread throughout the entire spawning bed.

"What was really telling was in nearby areas where we hadn't added gravel, the number of spawners really diminished," Dux said.

The spawning bed enhancement project is scheduled to continue for two more years.

When completed, about 4,000 cubic yards of gravel will have been placed along a half mile of shoreline.

The Idaho Department of Fish and Game will continue to evaluate the success of the project, but for now, biologists and fish alike are pretty happy with the new habitat.