Science activity

Description This is a continuation of a five year project funded by CDWR and CDFW and the Central Valley Project Improvement Act in 2017. The objective of the project is to improve estimates of population abundances for fall, winter and spring run juvenile Chinook Salmon at Sacramento and Chipps Island by improving efficiency estimates using data from releases of coded wire tags (CWT), acoustic tags (AT), and by genetically sampling the trawl catch in 2018. The project will (1) develop statistical models for estimating trawl efficiencies using 2016-2018 data for paired AT-CWT releases of winter run and fall-run Chinook Salmon;(2) use 2018 genetic sampling of trawl catch in combination with efficiency estimates to estimate population abundances of fall, spring and winter run at Sacramento and Chipps Island in 2018;(3) implement trawl efficiency studies for multiple salmon runs in 2018 informed by the 2016 and 2017 results and in coordination with hatcheries for inclusion of AT fish with existing CWT releases;and (4) combine trawl efficiencies with genetic samples of trawl catch to provide estimates of fall, spring and winter-run salmon abundance (with estimated precision) entering and exiting the Delta in 2018. Need There is growing appreciation that a salmon monitoring network that could quantitative estimates of abundance is desirable to improve our knowledge and resolution of life stage success and movement across the landscape (Salmon SAIL conceptual models 2016). Objectives (1) Estimate the population-level status and trends for winter run;and status of spring and fall run;(2) evaluate production estimates for juvenile winter-run Chinook Salmon entering the Delta used in water project take development;(3) provide estimates of winter and fall run-specific freshwater cohort strength to support ocean harvest management decisions;(4) establish a time series of winter, spring and fall run-specific production estimates at key locations for incorporation into life cycle models.