American River Steelhead Baseline Determination for Gauging Progress toward Delisting Steelhead and Increasing Reliability of Water Deliveries
* What methods can be used to determine how many Endangered Species Act (ESA)-listed steelhead live in the American River and in other rivers where abundance estimates are not currently available?
* How do flows affect steelhead spawning locations, timing, and egg to fry survival and how can flows be managed to sustain steelhead and increase water delivery capabilities?
* What proportion of in-river spawning steelhead are of natural origin?
* Are numbers of in-river spawners correlated with hatchery returns?
Need and Benefit
Abundance estimates of naturally spawning federally threatened Central Valley steelhead have never been obtained for the American River or for many other Central Valley rivers. Currently, fish entering Nimbus Hatchery, a Federal mitigation hatchery for the Central Valley Project (CVP), provide the only estimate of adult steelhead abundance. These hatchery fish counts do not count toward recovery goals for the species, nor do they provide any information regarding relative numbers of fish spawning in the river. National Oceanic and Atmospheric Administration (NOAA) Fisheries requires estimates of in-river spawning abundance for gauging progress toward meeting recovery goals for the species.
Reclamation began development of a protocol for estimating adult steelhead abundance in the American River in 2002 in cooperation with the California Department of Fish and Game. In order to develop an effective tool that can provide reliable abundance estimates of in-river spawning steelhead over time, this protocol needs to be refined and validated with steelhead data. Once the protocol is perfected, other groups will be able to use it into the future. Folsom project operations are determined in large part by steelhead abundance and distribution in the American River throughout the year.
Endangered Species Act requirements for steelhead in the Biological Opinion from NOAA Fisheries for operation of CVP facilities place operational constraints on CVP operations. Knowledge of effects of Reclamation operations on the species is needed for NOAA Fisheries to place reasonable terms and conditions on project operations. Reasonable terms and conditions should minimize impacts to water operations. The current NOAA Fisheries criteria for steelhead in the American River include temperature, ramping, and low flow criteria. This work will help to refine those criteria by showing relationships between flow and habitat use and provide some flexibility for water operations.
The American River is the only Central Valley river with such a steelhead abundance estimation protocol in development and thus was the only Central Valley Project (CVP)/ California's State Water Project (SWP) river with an adult abundance estimate in 2002. The lack of abundance estimates on the other rivers delayed NOAA Fisheries in providing a biological opinion in 2002 for the next two years of operations. The information being gained through this project is contributing towards critical information needs for long-term ESA consultations for operation of the Central Valley Project and State Water Project. The protocol developed through this work will likely be adapted to other Central Valley rivers.
Contact the Principal Investigator for information about these documents.