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Thousands of Kokanee dying in Okanagan Lake

by Brian Driscoll
Courier Staff
Tuesday, July 15, 1986

A viral infection may be killing thousands of young Kokanee in Okanagan Lake.

The Kokanee have been washing up on beaches from Squally Point to Okanagan Centre for the past five days, providing a culinary bonanza for birds and concern to Okanagan fishermen and Fish and Wildlife officials.

Samples of the dead fish have been sent by the provincial Environment Ministry to a lab in Nanaimo for analysis, though results of tests could take up to a week.

Brian Jantz, a Fisheries technician with the ministry in Penticton, said a viral or bacterial infection is suspected because only two-year old Kokanee have been killed. No other species are affected.

Jantz said the ministry first received reports of fish dying last Wednesday, but did not find any until Friday. The first large samples were gathered Sunday and sent to the lab Monday.

If a virus is causing the die-off, it may be difficult to prove.

Jantz said the samples must be dead less than 24 hours because the virus cannot survive in the dead fish.

There have been similar die-offs recently in Kootenay and Canim Lakes, and the cause was not determined in those cases.

Kokanee are more susceptible to viral infections than other species, Jantz noted, because they tend to stay in schools where the virus easily spread through skin contact.

Viruses can remain dormant for years in fish, he said, breaking out when conditions are right.

In the Kelowna area, hundreds of dead fish have been seen alongside Okanagan Lake Bridge and near Poplar Point.

Jantz said it is too early to estimate how many fish have been killed or how long the problem will continue.

The dead fish apparently pose no threat to birds feeding on the carcasses. And while the virus is not harmful to humans, Jantz recommends against eating fish found dead.

Kokanee caught live can be eaten, he said.