Project: Juvenile Salmon Outmigration and Distribution in the San Francisco Estuary

Introduction:

We will examine the survival and movement patterns of late-fall Chinook salmon (Oncorhynchus tshawytscha) smolts and steelhead (O. mykiss) smolts migrating from the upper Sacramento River to the San Francisco Estuary through the use of ultrasonic telemetry. This study can be viewed as a classic mark-recapture experiment with multiple recapture locations and complete capture histories. From the data collected we will be able to reconstruct each fish’s migratory pathway, and examine how natural and anthropogenic covariates affect reach specific rates/residence time and survival

Objective:

A detailed lifecycle model for Central Valley salmonids is seriously lacking in the realms of smolt survival and spatial-temporal migratory patterns. The data gathered from this project will be used to:

1) Describe reach-specific rates of survival and movement of juvenile steelhead and Chinook salmon from the upper Sacramento River to the coastal ocean.

2) Explain the variation in reach-specific rates by examining natural and anthropogenic covariates, such as water velocity, water temperature, habitat structure, etc.

Methods:

For three years we will surgically implant Vemco V7 tags into the peritoneal cavity of 200 late-fall Chinook salmon smolts and 200 steelhead smolts raised at the Coleman National Fish Hatchery (CNFH). These new ultrasonic tags are small enough that they do not affect swimming performance, predation rates, or growth rates of the juvenile salmonids. Tags will be implanted into the peritoneal cavity of ten Chinook salmon smolts and ten steelhead smolts each day, five days a week, for four weeks in January. After the ten fish from both species have been held for a post-implantation period they will be released, and ten of both species will be released each day until 200 of each species has been released. By spreading out when the smolts are released we can compare environmental variables affects on movements, and it will help to decrease the potential for “tag collisions” (fish not being detected because of multiple pinging at a monitor). We will be expanding the already existing array of 32 monitors in the Sacramento River used to record the movements of green sturgeon. The additional monitors will allow us to gain a better understanding of where juvenile salmonids may be diverted from their migratory routes, when they enter the Grizzly, Suisan, and San Pablo Bays, and when they finally depart from the San Francisco Estuary at the Golden Gate Bridge.

Progress:

N/A