Managing Interactions Between Fall-Run and Spring-Run Chinook Salmon Populations in the San Joaquin River Restoration Area

The San Joaquin River Restoration Program is required to attempt reintroductions of both fall-run and spring-run Chinook salmon to the stretch of the San Joaquin River below Friant Dam to the confluence with the Merced River (the Restoration Area).  Having both runs in the Restoration Area raises concerns for the potential of genetic introgression between the two runs and fall-run superimposing redds on top of spring-run redds.  Chinook salmon runs were extirpated from the Restoration Area over 50 years ago, so there is little information on run timing, spawning timing, and habitat use for each run.  The Program is undertaking an adaptive approach for minimizing the risk of hybridization and redd superimposition while informing potential future actions.  This approach includes targeted studies and monitoring to help determine the need for segregating the spawning of the two runs and the effectiveness of potential segregation methods.