Science activity

Spring-run Chinook salmon (Oncorhynchus tshawytscha) are a high-priority species under the Endangered Species Act due to their risk of extinction. However, understanding the factors affecting their populations is difficult when monitoring focuses only on returning adult spawners. This limited view overlooks critical life stages. To address this gap, the project aimed to estimate the number of juvenile salmon leaving the Delta at Chipps Island. Monitoring salmon throughout their entire life cycle is essential for identifying the key factors influencing their survival and reproduction.

There is a need from both scientists and managers for accurate data to make informed decisions about salmon protection and conservation. The Department of Water Resources (DWR) mandates that juvenile production estimates for spring-run salmon be included in their incidental take permit, which is necessary for the continued operation of the State Water Project. A method to estimate juvenile abundance of spring-run salmon leaving the Delta (at Chipps Island) did not yet exist.

To develop these annual estimates, researchers built on previous studies and incorporated new genetic data into updated models. This approach maximized the use of available information and the latest genetic research to improve the protection and understanding of these threatened fish.