Chinook Salmon

Nearshore habitat degradation due to human activities has had significant negative impacts on the ecosystem of the Pacific Northwest (PNW). It is estimated that 73% of the original salt marshes of the Puget Sound have been destroyed and that approximately 33% of the shoreline has been modified by human development (UW Urban Ecology Research Lab, 2009). Chinook Salmon (Oncoryhnchus tshawytscha), Pacific Sardine (Sardinops sagax), are two species that are both crucial to the PNW ecosystem, and have been affected in some way by human activities.

Chinook Salmon

Salmon are one of nine regionally endangered or threatened species that inhabit the Puget Sound nearshore (UW Urban Ecology Research Lab, 2009). They are both a keystone species that is vital to Puget Sound ecosystem, and one of the most important marine species to PNW life. Whether it’s attracting tourists at Pike Place Market, the pinnacle dish at a traditional PNW restaurant, or Fisherman’s livelihood Salmon play a vital role in PNW human life.

Erickson, Shari. Tule Chinook Salmon. 2008. Painting - Gouche. 2008. Web. 7 Mar. 2012.

            In 2002 the U.S. Fish and Wildlife Service conducted a study on the Habitat use of Juvenile Chinook Salmon in Lake Washington & Lake Sammamish from January through July. They conducted the study primary in the Littoral Zone of the lakes, and attempted to record the types of places in which Salmon juveniles favored the most and attempted to do one year comparison of Salmon juvenile numbers (Tabor et al. 2004).

What they found:

         Salmon numbers displayed a very strong negative correlation with the distance from the mouth of the Cedar River (Figure 1) (Tabor et al. 2004).

Figure 1. Density means for juvenile Chinook Salmon calculated from March 24 to June 16, 2002. Data was taken from the west and east shorelines of Lake Washington and Mercer Island Sites (Tabor et al. 2004).

            Juveniles tended to prefer a low gradient that was in close proximity to their natal stream (Cedar River or Issaquah Creek). 80% of the juveniles were located in areas with Overhanging vegetation and/or small woody debris (Figure 2). Juvenile Chinook Salmon also tended to prefer Deltas over Simple lake shoreline. Deltas had a higher density of Juveniles in 9 of the 14 sites they sampled and on average had twice as many fish (Tabor et al. 2004).

Figure 2. Daytime abundance of juvenile Chinook Salmon in both woody debris and open sections of shoreline. Data was collected from Gene Coulon Park, and south Lake Washington, March-June 2002. Each Shoreline section was 20 meters long (Tabor et al. 2004).

A Monthly mean abundance was also taken of juvenile Chinook salmon during night snorkel studies in six shoreline sites in Seward Park, south Lake Washington. Seward park was a recent restoration project attempting to establish a better nearshore habitat. The survey was conducted April-June in both 2001 and 2002. The data showed that although there was an attempt at restoration, juvenile numbers still declined in 2002 (Figure 3)

Figure 3. Monthly abundance of juvenile Chinook salmon conducted in 2001 and 2002 by night snorkel surveys in six separate sites in Seward Park, south Lake Washington.

Although there is a decline in the juveniles observed, this data is still hard to interpret into a certain outcome. This is due to the fact that the survey was only conducted over two years. If they could continue this survey then the results could certainly give us a much better idea on the livelihood of Chinook Salmon juveniles and their future.