Science activity

Description

The Mossdale Trawl occurs two miles downstream of Mossdale Landing County Park (river miles 56), and upstream of the Old River confluence. Timing and production (indices and estimates) for the out-migrating fall-run Chinook salmon smolts has been monitored at this location since 1987. Additionally this trawl captures coded wire tagged Chinook smolts and is the primary capture site for these fish being used to estimate survival of Chinook smolts in the river system. Results from this project, therefore document information on the out-migration timing, survival, and the magnitude of nonmarked smolt production from the San Joaquin Basin passing into the South Delta. The trawl also captures steelhead outmigrants and provides an index of these outmigrants for the entire San Joaquin River Basin.

Project Need

This project needs to identify annual juvenile Chinook salmon production in the San Joaquin River Basin. This project provides data supporting water management in the San Joaquin River basin and the Delta. Enumerating steelhead (Oncorhynchus mykiss) migrating through the San Joaquin River into the south Delta. Developing method to differentiate fall and spring run juvenile Chinook salmon migrating in the San Joaquin River basin.

Project Objectives

• What is the annual juvenile Chinook salmon production in the San Joaquin River Basin?
• How do water quantity and quality conditions affect smolt production trends?
• How many Oncorhynchus mykiss passage at Mossdale trawl?