Kokanee salmon vanish from Okanagan

People who fish B.C.'s most important Kokanee fishery say the freshwater salmon have all but disappeared.

Traditionally, Kokanee salmon have thrived in the Okanagan's Wood Lake but Anna Maria Ilinyczky, who has been fishing Wood Lake for more than a decade, says the fish just aren't biting.

"Even last year was much, much less than the previous years, but this year is getting worse."

Ilinyczky said algae are taking over Wood Lake. Pointing to a large bloom visible from the shore, she said it wasn't like this five years ago.

"[There's] definitely something wrong with the lake."

And provincial fisheries biologist Paul Askey agrees.

Askey says Wood Lake has always been nutrient-rich, which is why the Kokanee have traditionally thrived there, but too many nutrients from fertilizers or other sources can cause algae blooms.

The blooms then die and decay on the bottom of the lake — robbing it of oxygen.

"It seems like we might have gone past a tipping point in this last year, where it got too productive," said Askey.

He says hot temperatures last summer caused the lake to warm and algae to bloom, and that may have killed off many of the fish in the lake.

"The Kokanee would prefer not to be in water that is 20 degrees and above up in the warm layers —and they couldn't go down to the cooler waters because all the oxygen had been depleted by decomposing algae," explained Askey.

Askey and biologists from the Habitat Conservation Trust Fund are doing a five-year study of Wood Lake, including a fish count in the fall to see how many Kokanee remain.

Askey says recommendations from their study could include changes to the management of nearby streams vital for Kokanee spawning.