Shasta and Scott River Juvenile Salmonid Outmigrant Study, 2016

The 2016 Juvenile Salmonid Outmigrant Study is part of the ongoing work conducted annually by the California Department of Fish and Wildlife, Yreka Fisheries Program on the Shasta and Scott rivers in Siskiyou County, California. Using rotary screw traps, all age classes of outmigrating Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and steelhead trout (Oncorhynchus mykiss) were sampled from 29 January to 1 July of 2016. Mark and recapture trials were conducted multiple times per week to determine trap efficiencies and weekly population estimates. Established age-length cutoffs for each species were used to determine the age of the fish captured. In-stream conditions such as flow and water temperature were also monitored. Weekly estimates for the smolt class of all species were compared to show multi-year population trends. Using multi-year seasonal production estimates and coho salmon returns to the Shasta River, adult survival and smolt production estimates were calculated for Shasta River coho. It was estimated that for the period sampled in 2016, a total of 2,757,850 0+ Chinook, 164 1+ Chinook, 480 0+ coho, 229 1+ coho, 3 (actual number caught) 2+ coho, 11,749 0+ steelhead, 1,665 1+ steelhead, 30,501 2+ steelhead, and 6,045 3+ steelhead emigrated from the Shasta River. It was estimated for this same sample period, 56,634 0+ Chinook, 28 (actual number caught) 1+ Chinook, 14 (actual number caught) 0+ coho, 2,411 1+ coho, 1 (actual number caught) 2+ coho, 97 (actual number caught) 0+ steelhead, 73,540 1+ steelhead, and 44 (actual number caught) 2+ steelhead emigrated from the Scott River.