COEUR d'ALENE - Fish biologists on Friday announced they received welcome news following the completion of annual kokanee population surveys for Coeur d'Alene, Pend Oreille and Spirit lakes.

Biologists had been waiting for the results of the surveys to see whether or not the high water in May and June had taken a toll on the populations, said Phil Cooper, a spokesman for the Idaho Department of Fish and Game in Coeur d'Alene.

High runoff through Pend Oreille and Coeur d'Alene can cause a large portion of the kokanee population to "out-migrate," he said.

Jim Fredericks, a regional fishery manager, explained, "In essence, these (small) 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."

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, fisheries biologists use a mid-water trawl and hydroacoustics equipment, which is basically a high-tech fish finder, to estimate the abundance of the kokanee.

Fredericks said the work has to be done when the sky is at its darkest, meaning they work at night during the new moon.

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

Fortunately for biologists, anglers and the animals that depend on kokanee, it looks like most of the kokanee stayed home, Cooper said.

The strength of the kokanee population in Lake Coeur d'Alene has reached pre-1996 levels.

The 1996 and 1997 flood events put a dent in the population that has taken more than a decade to rebound, Cooper said.

Fredericks said, "For three years now, we've seen very good numbers of all age classes of fish, indicating the population has fully recovered."

The recovery in recent years has made it possible for Fish and Game to increase the limit from six fish last year to 15 now.

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

Andy Dux, a principal research biologist working on Lake Pend Oreille, said estimates show the highest number of kokanee spawners biologists have seen in Pend Oreille since 2004.

Additionally, juvenile kokanee were more abundant and should contribute to greater population increases in coming years.

The continued rebound of kokanee in 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.

Kokanee not only provide popular sport fisheries, but they are the prey-base for many large trophy fisheries, such as Chinook in Lake Coeur d'Alene and bull trout and kamloops rainbow trout in Lake Pend Oreille.

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 North 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.