Spokane, WA Weather

Wednesday, October 5, 2011

Kokanee Estimates Have Biologists Breathing Easier

By Phil Cooper - Idaho Department of Fish and Game

The Idaho Department of Fish and Game recently completed the annual surveys of kokanee populations in three northern Idaho lakes, and for the third straight year, were very encouraged by what they saw.

Each summer, biologists are out on Coeur d'Alene, Spirit and Pend Oreille lakes for several nights during the dark phase of the moon. While others sleep, they use a midwater trawl and hydroacoustics equipment, which is basically a very high tech fish finder, to estimate abundance of the small landlocked salmon.

The work has to be done when the sky is at its darkest, hence working at night during the new moon, said Jim Fredericks, regional fishery manager.

If there's any light at all, the kokanee can see the net coming and avoid it, which leads to an inaccurate population estimate," he said.

Biologists had been awaiting the results of the surveys to see whether the high water in May and June took a toll on the populations. History has shown that high runoff through Pend Oreille and Coeur d'Alene can cause a large portion of the kokanee population to out-migrate.

"In essence, these landlocked salmon treat the big lakes as their ocean, but in flood years like 1996 and 1997 there's a lot of current moving through the lakes, and the kokanee will follow it right out of the lake," Fredericks said. He had speculated - and hoped - that the high water in 2011 wouldn't be as detrimental as some previous years.

"This year, runoff wasn't exceptionally high, but it lasted several weeks, which is a different scenario than the very high magnitude, but short duration floods of 1996 and 1997," he said.

Fortunately for biologists, anglers and the animals that depend on kokanee, it looks like most of the kokanee stayed home. Andy Dux, a principal research biologist working on Lake Pend Oreille, said the estimates show the highest number of kokanee spawners they've seen in Pend Oreille since 2004. 

Additionally, juvenile kokanee were more abundant and should contribute to bigger population increases in coming years. The continued rebound of kokanee in Lake Pend Oreille indicates predator removal efforts have improved kokanee survival.

"If the upward trend we are seeing continues, I'm optimistic that we'll have a real shot at re-opening a kokanee fishery again within the next couple of years," Dux said.

In Coeur d'Alene Lake, the population was the strongest it's been since before the 1996 and 1997 floods put a dent in the population that's taken over a decade to rebuild.

"For three years now, we've seen very good numbers of all age-classes of fish, indicating the population has fully recovered," Fredericks said. The recovery in recent years has made it possible for Idaho Fish and Game to increase the limit from only six fish last year to 15.

"The fishery is back on, and anglers are taking full advantage of it," Fredericks said, noting that kokanee fishing has been very good all summer. 

Similar to Coeur d'Alene Lake, the population in Spirit Lake was strong across the board. 

Kokanee are small, landlocked sockeye salmon found in many lakes throughout the west. They not only provide very popular sport fisheries, but they are the prey-base for many large trophy fisheries, such as Chinook in Coeur d'Alene Lake and bull trout and Kamloops rainbow trout in Pend Oreille Lake. Healthy populations are not only important to anglers, but to many other animals as well, such as bald eagles.

Each fall, thousands of kokanee in northern Idaho lakes move to spawning beds around the shoreline where they deposit their eggs before dying. The abundance of spawned out fish draws dozens of eagles that have become the focus of a popular wildlife viewing activity. 

Phil Cooper is the regional conservation educator in the Panhandle Region.

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