Emigration and transportation stress of juvenile Chinook salmon relative to their reintroduction upriver of Shasta Dam, California, 2017–18

The Bureau of Reclamation supports the Shasta Dam Fish Passage Evaluation (SDFPE; Yip, 2015) program, and in 2016 set out to determine the feasibility of reintroducing winter-run and spring-run Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) to tributaries upstream of Shasta Dam. Ideally, reintroduction strategy includes trapping naturally produced downstream-migrating juvenile fish at the head of Lake Shasta (upstream of Shasta Dam), or near the mouth of the tributaries where they flow into the lake. However, evaluations of a juvenile collection system in one of the target tributaries (McCloud River) was delayed because of concerns about the fish source to be used as surrogate for winter-run Chinook salmon and the location and impact of the trap-and-haul operations.

In 2017, the U.S. Geological Survey (USGS) was contracted to evaluate the reintroduction of winter-run salmon into tributaries upstream of Shasta Dam, and the McCloud River, having the most suitable spawning and rearing habitat for salmon adjacent to Shasta Reservoir (Lake) was the chosen study area. The first stage of the project was to assess the feasibility using a head-of-reservoir fish trap to collect juvenile salmon, but these efforts were delayed, so efforts were used to assess how juvenile Chinook salmon would distribute within the McCloud River and Shasta Reservoir and help determine the feasibility of collecting fish at Shasta Dam. Importantly, NOAA fisheries was also conducting an acoustic telemetry project through the Sacramento River, and they provided the additional acoustic detection data on our tagged fish to San Francisco Bay. These data were collected beyond original study goals, but added a large contribution to the findings and inferences from this study.