Giant aquarium could save kokanee

KELOWNA — Okanagan Lake could be turned into a giant aquarium in an attempt to restore kokanee stock.

A large-scale experiment — with one pump sending air up from the bottom of the lake — is one of several recommendations included in a report now being prepared by the provincial environment ministry.

Eventually, up to 100 of the bubblers could be used in the lake.

One reason for the decline of kokanee was the introduction of mysis shrimp to feed rainbow trout. The shrimp eat the same kind of plankton as kokanee.

Scientists believe giant bubblers would pull shrimp off the bottom of Okanagan Lake, said Bruce Shepherd, head of the provincial fishery section in Penticton.

“The warmer water may shock or kill them, and fish can have at them,” he said.

However, other problems could arise from raising cold water to the surface, even in the middle of the lake, he said.

Recreational users of the lake could object and ling cod, which feed on shrimp at the bottom, could go after other fish.

Ten bubblers could cost $500,000 and at this point, “we’re very dependent on funding. There are no guarantees, but we should be better able to make our case,” said Shepherd.

As a result of a recent three-day workshop in Kelowna, he is preparing a draft action plan for kokanee recovery.
The plan, expected to be ready in August, will have a number of components from large-scale experiments to remedial action on kokanee spawning creeks to long-term research and development.

The number of spawning kokanee has dropped to 100,000 from one million during the past 20 years. The average size and age are decreasing.

Less kokanee survive today due to inadequate water flow as well as removal of spawning material from creeks.