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Kokanee salmon reside in Walsh Lake in the lower watershed.
Kokanee are a landlocked form of sockeye salmon (Oncorhynchus nerka). Kokanee populations occur in several tributaries of Lake Washington and Lake Sammamish.
Another form of sockeye salmon, called residual sockeye, are offspring of anadromous parents (migrating from ocean to freshwater to spawn), but do not migrate to the ocean. Kokanee are distinguished from residual sockeye because the parents were born in freshwater and have been isolated from anadromous sockeye for several generations.
Kokanee average between 7.0 and 11.7 inches in length in the Cedar River Watershed. Because of their smaller body size, kokanee require smaller substrate for spawning than sockeye.
The spawning color for both kokanee sexes resembles anadromous sockeye but the color may be duller in intensity. Males turn a reddish color and develop a hooked upper jaw (called a kype) and hump on the back, similar to anadromous sockeye salmon. Females are typically greenish in color with a slight reddish hue on the sides, and both sexes have distinct black spots along the back. In the Lake Washington Basin, kokanee have spots running along their back, but not on the head.
Some kokanee stocks in the Lake Washington Basin have declined. Careful monitoring by King County and volunteers is ongoing.
In the Cedar River Watershed, kokanee salmon are found in Walsh Lake. This population is small and lacks genetic diversity. This lack of diversity makes it difficult to determine how it is genetically related to other kokanee populations.
Kokanee spawn in Webster Creek, a tributary to Walsh Lake. In 2001, the City replaced an impassible culvert in Webster Creek with a bridge, which substantially increased available spawning habitat for kokanee.
Each fall since 1997, City biologists have monitored the spawning run of kokanee in Webster Creek and have found that kokanee spawning activity peaks at the end of October.
The size of the spawning run in Webster Creek is highly variable. The largest run of kokanee in the watershed between 1997 and 2010 occurred in 2002, when an estimated 590 fish were observed in 0.70 miles of stream on a single day. In some years no fish are observed. When spawning numbers are high, kokanee salmon spawn in dense aggregations in the stream, and sometimes redds are placed on top of other redds.
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Other fish species in the watershed: