Seattle Public Utilities Mami Hara, General Manager/CEO

 

Sockeye Salmon

 

sockeye spawning

Adult sockeye spawning in the Cedar River.

The sockeye salmon (Oncorhynchus nerka) is a common and relatively well studied species of the family Salmonidae. The sockeye is the third most abundant of the seven species of pacific salmon and has been targeted in major commercial fisheries for most of the twentieth century. Size at maturity varies considerably between and within populations of sockeye, with larger fish typically spending additional time at sea. The average weight of sockeye returning to the Cedar River is approximately 5.25 pounds.

Sockeye salmon are the most numerous naturally reproducing salmonids in the basin and, in years of high abundance, the population has supported a significant Tribal treaty harvest and one of the largest sport fisheries in the state.

The majority of sockeye returning to Lake Washington spawn in the Cedar River. The north Lake Washington subgroup also exhibits significant returns in most years. Returns to Issaquah Creek are typically lower than returns to the north-end tributaries. Lake spawners typically account for the smallest portion of the run, usually three orders of magnitude less than returns to the Cedar River.

Sockeye salmon exhibit a typical salmon life history pattern that integrates anadromy (juveniles migrate to the ocean where they mature and return as adults to spawn in fresh water), homing (adults generally return to their natal streams to spawn), and semelparity (adults die after spawning once). Unlike any of the other species of Pacific salmon, juvenile sockeye rear primarily in freshwater lakes.

Cedar River sockeye exhibit relatively protracted periods of spawning and incubation. Mature adults begin to enter the Cedar River in early September. Spawning activity begins to increase in mid-September and continues into January with a peak in mid- to late October. Each female selects a site for spawning, digs a redd, and deposits an average of 3,200 eggs.

Goals

Our long term goal for sockeye salmon is to increase the population from current levels. Our specific objectives include:

  1. Protecting water quality through habitat protection measures in the Cedar River watershed
  2. Provide appropriate flows to support sockeye salmon during river residence
  3. Acquiring and protecting property adjacent to the Cedar River below Landsburg Dam to reduce the impact of development activities on conditions in this area

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What are we doing?

Watershed Management Practices in the municipal watershed between Masonry Dam and Landsburg to protect water quality, aquatic, riparian and upland habitats and the processes that create and maintain a healthy river.

Instream Flow Management practices to promote a healthy river and provide beneficial habitat conditions for all life stages of Chinook salmon.

Downstream habitat protection and restoration along the 22 miles of river below Seattle’s municipal watershed to support flood plain management practices that help create and maintain beneficial habitat conditions throughout the lower river.

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