Juvenile Fall and Spring Run Chinook Salmon Route Utilization in the Sacramento-San Joaquin Delta

We conducted a survival and route selection study of juvenile fall and spring run Chinook salmon in the Sacramento San Joaquin watershed.  Several treatment groups of hatchery salmon were fitted with 0.3 gram JSATS transmitters.  Over 1000 juvenile Chinook salmon were tagged and released in the Sacramento and Feather Rivers.  Fall run fish were released at three locations along the Sacramento River.  Spring run fish were released in three groups, two at locations along the Feather River and one coinciding with a release group of fall run that were released in Sacramento.  Sacramento releases were timed to coincide with the arrival to the Delta of the fish released upstream.  Analyzing movements of fish trucked and released, that have not undertaken a complete out-migration may be problematic when attempting to extrapolate results to fish released at the hatcheries.  Previous studies suggest that mortality is in reaches immediately below release locations.  Our concern is that migratory behavior is also affected.  Our study sought to elicit differences in the migratory behavior of the treatment groups, as well as examine the factors affecting the route that the fished used during their outmigration.  Detections of fish were analyzed for transit time, route utilization, and survival.