White sturgeon are an anadromous fish species that reside primarily in the SAN francisco BAY delta and migrate asadults into the major rivers of the central valley to spawn

The U.S. Department of the Interior Fish and Wildlife Service awarded a $476,877 Formula Grant under the State Wildlife Grants (CFDA 15.634) program to the California Department of Fish & Wildlife (CDFW). The grant supports CDFW's efforts to develop and implement strategic, proactive conservation programs focused on protecting and managing white sturgeon, a species of greatest conservation need in California.

The grant funding will enable CDFW to establish fishery-independent surveys to more accurately monitor the population dynamics of white sturgeon, which have experienced significant population declines over time due to overfishing and harmful algal bloom mortality events. This data will allow CDFW to set appropriate harvest rate targets and implement regulations to help prevent further white sturgeon population declines and buffer against future impacts. The 3-year grant period runs from January 1, 2025 to December 31, 2027.

While white sturgeon support an active recreationalfishery, their periodic life-history strategy (late maturation, high fecundity, and episodic spawning) make themhighly vulnerable to over exploitation (chapman ET AL. 1996 hildebrand ET AL. 2016). Successful recruitment tothe adult population occurs approximately every 6-7 years and is highly correlated with high spring outflow (FISH2010). The abundance of legal-sized white sturgeon has declined considerably over time, and exploitation rateshave remained consistently higher than what is suggested for sustaining sturgeon populations. Based on markrecapturedata collected by the department, the current 5-year average abundance estimate is 33,000,representing a precipitous decline from estimates in the late 1990S ( 200,000 fish) (cdfw 2023). Despiteincreasingly strict harvest regulations for the fishery over time, harvest rates remain consistently higher thanrecommended for sturgeon species (5-10% beamesderfer and farr 1997) and for the population in california ( 3% blackburn ET AL. 2019). On average, harvest rate was estimated at 13.4% from 2007-2015 (blackburn ET AL. 2019),and 8.1% from 2016-2021 (cdfw 2023).white sturgeon experienced additional mortality during july and august 2022 when a major harmful algal bloom(HAB) of heterosigma akashiwo resulted in significant mortality of fishes from SAN pablo to south SAN franciscobays. The department recorded over 850 sturgeon carcasses, the majority legal-sized or larger (cdfw 2023), thoughit is thought that only a small percentage of the fish killed floated long enough to be detected (FOX ET AL.2020). The absolute magnitude of this impact on the white sturgeon population is unknown but is likelysubstantial. In late july 2023, another bloom of h. Akashiwo returned to SAN francisco BAY. The bloom was lessintense and of shorter duration than in 2022, but carcasses of 15 white sturgeon and 1 green sturgeon werereported. IT is likely that additional HAB induced mortality of fishes including sturgeon will recur in thefuture, and blooms could be severe depending on environmental conditions.since the 1970S, the department has relied on fisheries-dependent data from the adult mark-recapture taggingprogram for estimating white sturgeon abundance. This can produce estimates with a high degree of uncertaintywhen few tags are returned, while also precluding estimations in some years if returns are too low. Additionalbias is introduced from the low sturgeon report card (SRC) return rate ( 30%, hause ET AL. 2023), which containscritical data needed for annual abundance estimates. The department is currently proposing long-term regulationchanges for white sturgeon to prevent further population declines and help buffer against future impacts torecruitment that may result from recent and future HAB mortality events. These regulations will require moreactive management of the fishery in order to achieve a target harvest rate based on population abundance.therefore, IT is necessary for the department to develop fishery-independent surveys for monitoring populationdynamics of white sturgeon to more accurately and effectively set these targets for the fishery.