Urbanization in many coastal communities has severely reduced or eliminated salmon populations once common to these areas. The Pacific Northwest is one region where urbanization has had significant impacts on salmon. Chester Creek, which runs through the center of Anchorage, once supported a large population of coho salmon (Oncorhynchus kisutch). A significant impact on salmon access to Chester Creek occurred in the early 1970s when a weir and associated culverts were constructed at its mouth to create a recreational pond. The construction created a barrier that limited salmon passage. The purpose of this study was to evaluate the replacement of the weir and culverts in 2008 with a daylighted channel to restore natural passage of fish between the marine and freshwater environments. A major goal of restoration was to increase salmon abundance in Chester Creek. Annual monitoring of coho salmon returns from 2008 through 2013 using visual counts during the coho salmon run showed a 300% increase of coho salmon escapement from 481 in 2008 to approximately 1500 in 2009–2013. Estimated coho salmon smolt carrying capacities using several models ranged from 15 000 to 35 000 smolts. Based on these carrying capacity estimates, approximately 730 spawners should be sufficient to fully seed Chester Creek, and the observed increase in spawner escapement may therefore have little affect on smolt production. Results support the need for both extensive pre and post restoration monitoring to assess restoration.
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1 May 2016
Restoration and Coho Salmon Carrying Capacity of Chester Creek, an Urban Stream in Anchorage, Alaska
Richard L. Myers,
Shawna Nieraeth
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Northwest Science
Vol. 90 • No. 2
May 2016
Vol. 90 • No. 2
May 2016
carrying capacity
restoration
urban salmon