Red Bluff Diversion Dam - Green Sturgeon
The Red Bluff Fish and Wildlife Office (RBFWO) established a green sturgeon research and monitoring program centered on the Red Bluff Diversion Dam (RBDD) in 2001. Rotary trapping activities had documented the capture of age-0 green sturgeon in every year of operation since 1995.
Sampling for green sturgeon eggs to determine spawning locations and sampling of larvae to determine habitat use and drift characteristics was originally funded by a grant through CALFED. Sampling was conducted in the spring and summer of 2001, but the project was discontinued after a single season. The primary results of that project were that green sturgeon eggs were sampled immediately below RBDD and a single larvae was sampled several kilometers upstream of RBDD indicating spawning was occurring above and below the dam. It was noted that the RBDD created an impassable barrier to late arriving adult spawners. For the complete results of this work, see below.
In 2007, renewed concern over the impacts of RBDD in relation to the recent Federal Endangered Species Act listing of the Southern Distinct Population Segment of the North American Green Sturgeon as Threatened prompted renewed interest in determining basic life-history information of the only known spawning population which occurs in the area of RBDD on the Sacramento River. Coordination by the US Bureau of Reclamation (USBR), the US Fish and Wildlife Service, and the University of California at Davis (UCD) resulted in renewed efforts to initiate a number of studies on the adult spawning population. From this coordination, it was determined that the RBFWO would reinitiate the egg and larval studies for a period of three years (2008-2010) and use acoustic telemetry data provided by USBR and UCD to guide the efforts.
Sampling for green sturgeon eggs began in the spring of 2008 using a variety of substrate sampling devices. Real time acoustic data was used to determine sampling start dates and for increasing the precision of sampling locations. With little knowledge of exact spawning locations, a sampling regime of upstream, within, and below known sturgeon holding areas was tested. In a nutshell it was determined that green sturgeon eggs were sampled exclusively in the within pool areas. The efforts have been and continue to be further refined as data has been collected from the 2009 and 2010 seasons with multiple spawning sites confirmed above, at, and below RBDD.
Sampling for drifting larvae using a benthic D-net also commenced in the spring of 2008 at four sampling locations centered on RBDD (2 above and 2 below) following the sampling of green sturgeon eggs. All sample locations were experimentally sampled in a pilot effort to see if trends or patterns existed on nocturnal distribution patterns to better guide future sampling efforts with limited resources. The results of the 2008 - 2012 work can be found below in our Final Reports Section. Survey work in 2012 included a pilot effort to sample juvenile green sturgeon. Results were limited and can be found in the 2012 report. Future efforts include expanded juvenile green sturgeon monitoring efforts that will initially focus on the use of experimental trawls, gill nets, and traps (i.e., gear comparisons) to determine feasibility of capturing juveniles and subsequently determining habitat use. These efforts will commence in the summer of 2014 and the results will be posted in 2015
Final Reports on Green Sturgeon