Don's Home California Salmon Habitat Restoration 2023/2024 Chinook Salmon estimate

Andrew Rypel, Coldwater Fish Ecology at UC Davis in the Department of UC Davis Department of Wildlife, Fish and Conservation Biology, April 2024

The crew handled a total of 446 adult Chinook carcasses this field season. We also did the most exhaustive series of carcass surveys of the upstream spawning grounds since work began on the creek. As part of that effort, we conducted a large mark and recapture study on the spawning ground carcasses to better estimate population size. These surveys were complimented by more targeted carcass surveys in other reaches of the Creek. Major props to Anne, Alex, Peter and the entire UC Davis and SCWA crew for all their hard and herculean work collecting these data!

The preliminary result of the effort and using a pooled-Peterson population model is that there were ~735 adult Chinook salmon in Putah Creek this fall/winter. The majority of these fish were located on the upper spawning grounds. We may continue experimenting with other estimation approaches, and ways to generate uncertainty around the estimate. Nonetheless, I wanted to give you all an updated state-of-the-science number that we feel good about for the time being. It is excellent and astounding to me that the run has reached this many fish.