Estimated Sockeye Salmon Eggs to Emigrant Survival Rate in Cedar River and Bear Creek



The majority of sockeye salmon in the Lake Washington basin are produced in the Cedar River. Bear Creek, a tributary to the Sammamish River near the north end of the lake is the second largest producer of sockeye in the basin. Sockeye eggs and alevins (larval fish) incubate in the gravels of the streams during the fall, winter and spring. As the young fish emerge from their redds (gravel nests) in the spring, nearly all move directly downstream into Lake Washington where they typically rear for about one year before migrating to sea. The rate at which incubating sockeye survive is one measure of general incubation conditions in the stream. Incubation survival, measured here as "egg to emigrant survival", can vary widely from year to year. One of the major factors affecting survival appears to be the magnitude of flood events in any given year. Large floods can scour eggs and alevins out of the gravel resulting in relatively high mortality rates.


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