Author: Amanda Peterson

The Bureau of Reclamation, partnered with the California Department of Fish and Wildlife, has been monitoring rotary screw traps along the upper portion of the San Joaquin River below Friant Dam in order to estimate juvenile production.

In recent years, more returning adults have been seen in the upper reaches of the river bring increased excitement for the natural return of this run. In 2021, parties were interested in understanding the survival and movement rates of natural origin Spring-run Chinook smolts within the upper river’s restoration area. Multiple parts of the restoration area has not been restored yet and provides many obstacles for juveniles to pass, like Sack Dam, Mendota Pool and shallow waters along the river. UC Davis was fortunate to be asked to conduct tagging of natural origin Spring-run juveniles as they were captured in the rotary screw trap, this being the first time natural origin Spring-run smolts were tagged on the San Joaquin River.

Lead by Master’s candidate Amanda (Agosta) Peterson, receivers were deployed throughout the upper reaches of the river to detect the tagged smolts. The team worked with private landowners and the San Joaquin River Restoration Program to access new receiver site locations. The study was successfully completed in 2021 and analysis is underway.