Race on to save Kootenay Lake’s crashing kokanee population
Biologists are seeding streams around Kootenay Lake with hundreds of thousands of fish eggs this fall and plan to release at least 500,000 hatchery fish next spring in response to a kokanee salmon population crash.
Kokanee spawning returns began to fall in 2012, but reached a shocking low of 7,630 fish this year in Kootenay Lake’s main spawning channel at Meadow Creek, a drop of more than 98 per cent from the average return of 670,000, according to the ministry of forests, lands and natural resource operations.
The provincial government and the Freshwater Fisheries Society already released 95,000 fry into two tributaries of Kootenay Lake this year in response to the unexpectedly low return. The lake’s kokanee population has never dropped so low, said Kootenay resource manager John Krebs.
“This is right off our charts,” he said. “We don’t normally raise fry or collect eggs for Kootenay Lake, it has been self-sustaining through natural spawning.”
The kokanee appear to be suffering heavy predation from bull trout and Gerrard trout, which ballooned to record numbers between 2009 and 2012.
A government bulletin in May noted low numbers of one- and two-year-old adult kokanee in the lake, which will result in at least two to three years of low spawner returns. If Gerrard numbers cannot be controlled, kokanee returns could remain depressed for up to eight years.
To preserve breeding stock and rebalance the food web, the Kootenay Lake kokanee fishery was closed April 1 and the quota for Gerrard trout doubled from two to four fish per day. The results of those changes won’t be known for almost a year.
A nutrient enhancement program to stimulate growth of zooplankton, a kokanee food source, will be extended this fall in an effort to improve the kokanees’ survival over the winter.