Lake Sammamish Kokanee (Oncorhynchus nerka) – Part 3

Tuesday, June 19, 2012 at 03:22PM
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The future of kokanee in the Lake Sammamish & Lake Washington watersheds:

Research is being done to create a climate change model for Lake Sammamish as way of predicting impact on the kokanee. I know I’ve been aware in the last few years that summers seem wetter and cooler. Some climate predictions do say we’ll have wetter summers.

Kokanee spawn when they are three to five years old at about 10 to 20 inches long. They spawn in November to January, the same time as the historic winter run. Nobody knows if earlier runs will return.

In 1896 the kokanee population was estimated to be 200,000 in Lake Washington and Lake Sammamish. In 1947, they had decreased to 165,000; in 1972 about 30,000; in 1980 the population was down to 2,000.

Going forward there is a three pronged strategy to conserve the species: Protect the population and habitat, reconnect the population to the habitat and restore the population to a level that would allow recreational fishing of the species once again.

Strategies to protect the population include the supplementation program now under way at the Issaquah Salmon Hatchery. Spawning adults are scooped up from Ebright, Laughing Jacobs and Lewis creeks each winter, raised in their home waters at the hatchery, and then released back into their respective creeks in the spring. The process includes holding the adults until they are “ripe”, collecting genetic samples, spawning the eggs, incubating and marking the eggs, imprinting them on their natal stream by collecting water from those streams and exchanging it for water in the hatchery every week, rearing the fry and returning them to their natal streams. The objective is to minimize the time or the influence the hatchery has on the fish and get them to stream as soon as possible.

It is a labor intensive process that is having some very promising results. Fish are released into their natal streams at night in April when zooplankton is becoming prevalent. Scientists working on this project were pleasantly surprised to see more spawners returning to the three creeks last winter than were found in previous years and this past April 62,367 fry were released. This effort began in 2009 and will continue to 2025.

There are efforts to maintain the existing habitat intact, to promote awareness of the endangered species with the public and with anglers and to prevent the introduction of invasive species. The impact on habitat has been tough for the fish. The hatchery program is an effort to maintain current stocks and give the species a chance to survive while habitat is fixed or improved.

Replacing culverts under roads that are not friendly to spawning kokanee will help to reconnect the fish to their native streams and habitats, an effort that is just getting under way. That effort will go forth through 2018.

Restoration efforts will begin next year in earnest and continue through 2025. They include re-introducing kokanee to historic streams other than the three now known to hold them and an assessment of streams for their capacity and restorability.