Chinook salmon
In addition, Deer Creek is a refugial stronghold for spring-run Chinook salmon ("Oncorhynchus tshawytscha"), and the stream supports Central Valley anadromous steelhead trout ("Oncorhynchus mykiss"), fall-run Chinook salmon, late-fall-run Chinook salmon, and Pacific lamprey ("Entosphenus tridentatus"). Historically, spring-run Chinook salmons populations averaged around 2,800, but numbers began to decline in the 1980s to the low hundreds.