Sturgeon Scientific Literature and Annotations
*This is a 3-part series on Sturgeon Facts, Science and Populations by Tom Cannon, for questions email him at thomascannon0@gmail.com
To read the full article, Click Here.
- 2011 San Joaquin River Sturgeon Spawning Survey (Gruber et al. 2012)
- White sturgeon (Acipenser transmontanus) in the Sacramento-San Joaquin river system were previously known to spawn only in the Sacramento River within a 86 km reach between Knight’s Landing (RK 145) and Colusa (RK 231).
Comment: White sturgeon were noted historically in the Sacramento and San Joaquin Rivers and their tributaries.
- The results of this survey confirm that white sturgeon do spawn in the San Joaquin River and may be an important source of production for the white sturgeon population in the Sacramento-San Joaquin river system.
- In April 2011, the collection of white sturgeon eggs documented white sturgeon spawning in the San Joaquin River.
- Average daily discharge in the San Joaquin River in early 2011 was two to three times higher than the mean daily discharge for water years 1991 to 2010 (Figure 5). As speculated by researchers, river discharge levels of this magnitude triggered white sturgeon to enter and spawn within the San Joaquin River System.
Comment: Juvenile white sturgeon were collected in the daily salvage at the Tracy Pumping Plant in summer of wet year 2023 under high exports (Figure A-1). River flows had been very high in May and June in the San Joaquin River (Figure A-2) upstream of the Delta. That fact along with salvage predominantly occurring only at the Tracy facility indicates that these salvaged juvenile white sturgeon were likely from the San Joaquin River. Such high flows in wet years are likely conducive to white sturgeon attraction and spawning in the San Joaquin River system. Spawning usually occurs when water temperatures are 55-65oF (13-18oC), which were the conditions in the lower San Joaquin River above the Delta in spring 2023. The presence of juvenile sturgeon in the summer salvage indicates this period marked key river emigration to Bay-Delta nursery habitats from the San Joaquin River. However, Lower San Joaquin River and Old River water temperatures (Figures A-2 to A-4) in summer 2023 ranged from 70-80oF, well above the 68oF safe level for juvenile sturgeon, and often well above the high-stress level of 73oF. Even if closure of the Head of Old River on the San Joaquin River were considered, water temperatures are generally excessive (>75oF) by July for juvenile sturgeon survival through the East, South, and Central Delta – even in wet years. Though sturgeon may spawn in the Lower San Joaquin River, their potential contribution to recruitment in the adult Bay-Delta population is therefore likely minimal in all water year types. It is for this reason that any juvenile sturgeon salvaged in summer (or captured in monitoring in the lower San Joaquin River or the Delta) should be transported to our proposed sturgeon conservation hatchery for rearing and release to the Bay. It may be best in summer to leave the HORB open to allow salvage or the rescue option, otherwise the juvenile sturgeon may be lost in the interior Delta. Juvenile sturgeon can be captured at the HORB in summer and reared in the conservation hatchery. In drier years, we expect less spawning in the lower San Joaquin River and few juvenile sturgeon to survive to reach the HORB unless determined otherwise by monitoring.
Tom Cannon is an estuarine fisheries ecologist and biostatistician and has been involved in Delta fishery issues for more than 35 years. Over that period, Tom has worked for or been a consultant to the California Department of Fish and Wildlife, U.S. Bureau of Reclamation, National Marine Fisheries Service, State Water Contractors, CalFed Bay-Delta Program, State Water Resources Control Board, PG&E, California Striped Bass Association, Fisheries Foundation and CSPA. He has been involved in numerous habitat restoration projects. Find his reports on https://calsport.org/fisheriesblog/
*Note: NCGASA is providing a place for more information on sturgeon, but all of Cannon’s recommendations do not necessarily represent the views of our organization.
