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Okanagan Lake fishery in danger

Kokanee stocks must increase
by John Keery
Courier Staff
Kelowna Daily Courier
Monday, January 11, 1988

A provincial fisheries official and a spokesman for the B.C. Wildlife Federation agree the fishery in Okanagan Lake could collapse under current fishing pressure if stocks are not increased.

“We are worried that if nothing is done to enhance the kokanee we could see a collapse of the fishery in the next 10 years,” says federation spokesman Rene Barone.

Although Barone, chairman of the federation’s fisheries committee for the Okanagan Region, agrees with government biologists that the reasons for the kokanee decline are unclear, he says efforts to try and reverse it should be undertaken immediately.

“Fisheries are reluctant to do anything before they find the problem,” he said.

Fisheries biologist Chris Bull says although fishing is currently good there are a number of indications that stocks are declining.

“The fact that the size is good is another indication that the numbers are down,” Bull said.

One theory is that a new freshwater shrimp introduced into the lake in 1966 could be competing with newly-hatched kokanee for food. This would reduce the survival rate of kokanee but increase the amount of feed available for adult fish, causing them to grow larger.

The number of spawning kokanee has been declining steadily in the past few years, Bull said. Until last year it appeared that shore spawners were on their way to extinction.

Then this fall, numbers shot up to 165,000, from 2,000 to 3,000 in the past several years.

“We don’t even have a theory (to explain this),” Bull admits.

He also has no explanation for a massive dieoff of two-year-old kokanee in the summer of 1986. Studies of the dead fish revealed no apparent cause.

Bull said dieoffs and rapid fluctuations of kokanee populations also occur in other lakes in B.C. and the United States.

Mature rainbow trout eat kokanee, so if kokanee levels decline too far, it affects rainbow stocks.

Loss of spawning areas is a major factor affecting kokanee populations.

Bull estimates about 90 per cent of the spawning capacity in streams entering Okanagan Lake has been lost since 1900.

Creeks have been channelized, gravel beds silted up and water levels reduced due to irrigation demands.

Bull says water conservation measures will eventually have to be brought in in the Okanagan to preserve the fishery. “We just can’t keep on using water willy-nilly and still have a fishery.”

The wildlife federation wants fisheries to build a hatchery on the lake and increase spawning success with a new spawning channel.

Fisheries began diverting the million per year kokanee produced by the Skaha Lake hatchery to Okanagan Lake last summer.

The fish did not appear to be surviving longer than two years in Skaha. Bull says he does not know why. But similar problems have been experienced in lakes the size of Skaha in the United States.

The federation has a proposal for a hatchery at a beach south of Summerland which would produce up to 10 million kokanee per year for release into Okanagan Lake. It says the hatchery would cost about $700,000 and would require just one fisheries employee halftime to operate.

The federation also wants changes to the provincial Water Act which would force water users to release sufficient water for spawning fish during critical periods.