For many years most anglers and fisheries biologist had a rough idea of striped bass (Morone saxatilis) movements between the fresh water Delta and tributaries, and marine waters of the San Francisco Bay and beyond. Conventional wisdom tells us that the majority of striped bass move from saltwater into the lower reaches of the Sacramento and San Joaquin Rivers in the spring to spawn, then move to the lower Delta during the summer before migrating back out through the San Francisco Bay to the ocean in late summer and early fall. However, with advances in fisheries technology results from recent research are beginning to challenge the conventional wisdom.
As you can see from this video captured from a Vaki Riverwatcher electronic fish counting system installed at the weir on the lower Tuolumne River, striped bass of all age classes can and do migrate upriver during the fall. It is not clear whether the bass we have detected moving upstream in the fall are migrating, or if they are resident fish that are present year round and are just moving throughout their range. This fish counting weir was installed on September 9, 2010 and has detected 17 striped bass through September 20, 2010 migrating upstream.
Video source: FISHBIO