Sacramento River green sturgeon migration and population assessment
Introduction:
Our current study addresses the needs of the Bureau of Reclamation (BOR) and other Department of Interior co-managing agencies (U.S. Fish and Wildlife Service (FWS)) by gathering information on the population status and critical habitat of green sturgeon in the Sacramento River. This research is focused around Red Bluff Diversion Dam (RBDD), Lake Red Bluff and ACID and will result in information about potential impacts from these in-river diversion facilities. It will focus on gaining information regarding the spatial and temporal distribution of green sturgeon through this portion of the Sacramento River riverscape using genetic, telemetric, and traditional field sampling methods. These surveys will result in a suite of estimates for green sturgeon spawner abundance, and egg/juvenile production above and below RBDD. These comparisons will provide initial guidance for establishing juvenile and adult monitoring surveys for abundance indices.
Objective:
Research assessing the presence of various life history stages of threatened Sacramento River green sturgeon around Reclamation facilities during their peak spring and summer use is directly linked to improving fish passage and minimizing impacts of operations pursuant to state water plans (i.e. CVPIA). The telemetric objectives of this study (below) are part of a Cooperative Ecosystem Studies Unit research study with FWS and BOR including green sturgeon egg and larval sampling, intraannual genetic comparisons of egg, larval, and adult green sturgeon samples; and development of standardized monitoring protocols for green sturgeon in the Sacramento River.
1. Evaluation of habitat use, spawning behavior, and migration by individual green sturgeon above and below RBDD.
2. Assessment of green sturgeon movement and behavior in Lake Red Bluff.
Methods:
Between May 15 and August 15, 2008, UC Davis will cooperate with BOR and FWS to collect and tag individuals below Red Bluff Diversion Dam within a week of it being lowered. Half of the captured green sturgeon will be placed above or below the Dam and monitored through the acoustic monitoring system being maintained in the Sacramento River by UC Davis and other collaborating organizations. A Radio Acoustic Position (RAP) system will be placed in Lake Red Bluff to characterize fine-scale green sturgeon use of this temporary impoundment, including swimming depths. UC Davis crews will cooperatively maintain the RAP system with USBR and USFWS during their two months of field work and provide a portable ultrasonic receiver and hydrophone, as well as five depth-recording ultrasonic transmitters. Data will be analyzed to compare spawning behavior, habitat utilization, and movement between the two groups of fish above and below Red Bluff Diversion Dam. Previously tagged, returning green sturgeon will also yield information about migration, spawning, and behavior around Red Bluff Diversion Dam, Lake Red Bluff, and ACID.
Progress:
In 2008, this study is in its first year. Ten adult green sturgeon were captured and tagged with ultrasonic coding beacons, between April 23 and June 11, 2008. Five individuals were tagged below RBDD prior to the May 15 lowering of RBDD gates to allow for passage upstream. An additional five individuals were tagged below the gates after RBDD was implemented. Two of the adult green sturgeon captured were double tagged with continuous transmitters and tracked by boat for a period of three to four days.
Discussions with regulatory agencies prevented us from capturing adult sturgeon above the RBDD. Since no fish were tagged upstream of RBDD we did not use the RAP system for evaluating movement just upstream of RBDD in Lake Ref Bluff. Based on recent discussion, we are considering tagging green sturgeon earlier in the season upstream of RBDD in an attempt to possibly utilize the RAP system in 2009
Funding has been allocated for the 2009 field season.