Bar codes help kokanee salmon in their survival

April 20, 2010

Fish Journal

Under the direction of the Washington Department of Fish and Wildlife, the efforts of the Lake Sammamish Kokanee Work Group to increase dwindling kokanee salmon numbers in Lake Sammamish are now underway.

Kokanee salmon have been entwined within the history and culture of native and immigrant residents of Lake Sammamish since the Ice Ages. See a previous Fish Journal piece, “Tribal Tales of the Kokanee Trout Clan,” published in The Issaquah Press and on the Web here.

The Kokanee Work Group is comprised of state, county and city municipal officials, conservation organizations, and individuals from King County and surrounding communities. All are highly motivated to save the late run species of native kokanee from an extinction experience similar to that of the early run kokanee in Issaquah Creek.

This winter, fish biologists captured male and female Lake Sammamish kokanee returning to several tributary creeks. More than 34,000 eggs were harvested, fertilized with milt from males and placed in incubation trays at the Cedar River and Chambers Creek state fish hatcheries. Read more

Scientists release kokanee fry to re-establish species

April 13, 2010

On a rain-soaked night late last month, scientists gathered along the banks of Ebright Creek to complete the latest step in a monthslong experiment meant to pull a species from the edge of extinction.

The team used buckets to transfer Lake Sammamish kokanee salmon fry — a few millimeters long and not much larger than a paperclip — from aerated coolers for the last leg of the journey from a hatchery to the wild.

Months earlier, biologists and ecologists collected mature kokanee from the same creek, as part of a last-ditch effort to boost the population of the dwindling species. From Ebright, Lewis and Laughing Jacobs creeks, teams took the fish to the Issaquah Salmon Hatchery, where teams harvested almost 35,000 eggs.

Scientists had not attempted to raise Lake Sammamish kokanee at a hatchery before. Throughout fall and winter, workers at the state hatcheries in Ravensdale and Lakewood raised the fry from fluorescent orange eggs.

Hans Berge, a King County senior ecologist, and a team gathered March 25 to release about 14,000 fry into the same creeks where he and others netted spawning salmon last fall. In a reverse maneuver, the team plunked the fledgling kokanee into the creeks on a cloudy, wet night.

The nighttime release offered less risk of predators picking off the fry.

Scientists deposited the fry far upstream from Lake Sammamish to allow the fish time to “imprint” on the creeks. Biologists hope the fry memorize the characteristics of the waterways and someday return to the creeks as stop-sign-red, mature salmon to spawn.

Berge estimates the fry swam from the creeks into the lake on the same night as the release. Inside Lake Sammamish, the fry feed on microscopic organisms called zooplankton. Only a fraction of the fry will reach maturity and — in three or four years — return to the creeks to spawn.

Within the next few weeks, scientists will release another 20,000 kokanee fry into Ebright, Lewis and Laughing Jacobs creeks. Read more