Since 2000, the Anadromous Fisheries Resource Assessment and Monitoring Program conducted by the Yreka office of the California Department of Fish and Wildlife has operated rotary screw traps in the Scott and Shasta
Rivers of the greater mid-Klamath River basin for the purpose of generating population estimates for out-migrating juvenile salmon. The traps are installed in late winter (Julian week 5 – January 29) and operate until late spring (Julian week 26 – July 1), depending on conditions. Three species of salmonid are monitored, including Chinook salmon (Onchorhynchus tshawytscha), coho salmon (O. kisutch) and rainbow trout/steelhead (O. mykiss), as well as a variety of native and non-native fish species. This report is a summary of data collected regarding juvenile Chinook populations from 2000 to 2015. Seasonal population estimates at the Scott River trap site ranged from 17,000 in 2006 to a high of 1,190,000 fish in 2009. Production estimates from the Shasta River ranged from 90,000 in 2006 to 5,975,000 individuals in 2013. Out-migration timing, estimated trap efficiencies and fork length bio-data are provided. Water temperature and flow data collected since the inception of the project are also presented.