We are documenting and describing the ecology of steelhead in a small central California coast stream to better understand the variable nature of these populations and how they persist in a dynamic environment that features frequent floods, debris inputs, drought, and wildfire. Understanding steelhead responses to disturbance in these highly variable watersheds is critical for our ability to protect, conserve, and recover steelhead in California and throughout the West Coast.
We are using a range of methods in our research, including sampling fish in the spring and fall, tagging fish with passive integrated transponders (PIT), and collection of fin clips for genetic analyses. Our sampling allows us to estimate the abundance of fish, measure growth, track movement of fish, and to understand relationships of fish within Big Creek watershed and among other West Coast watersheds through time, and provides us the opportunity to examine differences in life history of these fish that includes anadromous steelhead (mature in the ocean like salmon) and non-anadromous rainbow trout and the temporal variability of these data in the context of dynamic environments. We have been examining the food web of steelhead in Big Creek with diet studies that described the seasonal variability in types (e.g., non-native isopods, mayflies, etc.) and the amount of items fish are eating including the different sources of the food that includes terrestrial sources (e.g., insects dropping into the stream from an overhanging branch) and aquatic invertebrates.
This project is the longest on-going study of steelhead in a coastal watershed south of Monterey Bay. Results from this study have been used to support recovery planning and assessments of the local and regional status of steelhead, and have provided context and critical information on impacts of drought, high flows, wildfire, and changing ocean conditions.
(Big Creek photos courtesy Lobsang Wangdu/UC Natural Reserve System)