Southern DPS green sturgeon (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) populations have been severely reduced due to dams, diversions, habitat degradation, and both legal and illegal harvest. The Sacramento River system is the only river system supporting spawning of the federal threatened southern Distinct Population Segment (sDPS) green sturgeon and the is the primary river system supporting spawning of white sturgeon. Green sturgeon spawning has been documented in a 93 km section of the Sacramento River from Hamilton City (river kilometer [RK] 332.5) upstream to Cottonwood (RK 426) (Poytress et al. 2013) and in the Feather River in the vicinity of the Thermalito Bay Outlet in mid-June 2011 (Seesholtz et al. 2015). The majority of white sturgeon are thought to spawn in the middle Sacramento River between Knights Landing (RK 142) and Colusa (RK 237) (Schaffter 1997). Both sDPS green sturgeon and white sturgeon have been observed in the Yuba and Bear rivers, however; there is no documentation of either species spawning in these rivers.
Egg mats were constructed by securing a furnace filter insert to a 76×107×5-cm rectangular steel frame rigged with a 9.5 mm diameter braided polypropylene rope attachment bridle, 9.5 mm diameter buoy line of sufficient length, and a 10-inch diameter inflatable buoy to mark the egg mat location and facilitate retrieval. Once a suitable sampling site was selected, the mat was deployed by gradually lowering it to the river bottom from the bow of the boat while holding the boat stationary in the current. When the egg mat reached the river bottom, the buoy was deployed and observed for several minutes to insure the egg mat remained in place. Deployment date and time and water depth and temperature were recorded at mat deployment site. Flow velocity at each mat deployment site was estimated to the nearest to the nearest 0.3 meter per second and substrate composition was determined from visual observation and DIDSON surveys of the sampling site. Egg mats were retrieved by slowly hauling in the float line to avoid dislodging adhered sturgeon eggs and gently lifting the mat into the boat. Two CDFW staff conducted a thorough visual inspection of each egg mat to check for sturgeon eggs prior to re-deployment.
This report documents findings from the second year of a California Department
of Fish and Wildlife (CDFW) study to determine if southern Distinct Population Segment (sDPS) green
sturgeon (Acipenser medirostris
) and/or white sturgeon (Acipenser transmontanus
) spawn in the Yuba
River, and if so, what are the temporal, spatial, and habitat requirements associated with sturgeon
Yuba River Sturgeon Spawning Survey Report-2019.pdf
Yuba River Sturgeon Spawning Survey Report-2018.pdf
Author: Marc Beccio
Publisher: CDFW Region 2 Anadromous Fisheries
Publish Date: 11/28/2018