Movements of steelhead (Oncorhynchus mykiss) smolts migrating through the San Francisco Bay Estuary

We used acoustic telemetry to monitor the out-migration of 1,000 steelhead smolts (Oncorhynchus mykiss) through the San Francisco Bay Estuary during spring of 2009 and 2010. The smolts transited the estuary rapidly (2–4 days) and utilized flows in the main channel during their migration. Fewer smolts were detected in marinas, tributaries and other shallow areas surrounding the estuary. Many of the smolts made repeated upriver and downriver movements that were related to the tidal flow, moving upstream during flood tides and downstream during ebb tides. These results show that steelhead smolts migrating from the Sacramento River transit rapidly through the lower reaches and do not use the estuary for feeding, rearing, or smoltification purposes.