Searching For Answers: What Are Green Sturgeon Doing in the Lower Feather River

1. Alicia Seesholtz1, Matthew Manuel2, Darren Rocheleau2, Timothy Vieira1, and Kevin McAllister21 California Department of Water Resources, Division of Environmental Services2 Pacific States Marine Fisheries Commission Searching For Answers: What Are Green Sturgeon Doing in the Lower Feather River Abstract Information that currently exists on the threatened southern DPS (sDPS) of North American green sturgeon indicates that the mainstem Sacramento River in California, U.S.A., is the only known spawning area for the species.. The majority of in-river data on sDPS green sturgeon is also from the Sacramento River. Yet, recent observational and anecdotal information indicate that small numbers of green (and white) sturgeon are found in the lower Feather River in most years. Therefore, determining how green sturgeon use the river is important to sDPS recovery. Introduction Objectives Results • = DIDSON footage of sturgeon Lake Oroville • Regarding the Feather River: • Historic numbers and range of sturgeon unknown • Lower Feather River listed as Critical Habitat (2009) • Passage issues • Greens never sampled in studies (1960’s on) – all info anecdotal • Spawning assumed but not documented • Determine if there is a (potential) second viable spawning population of sDPS green sturgeon • Identify distribution and habitat preferences; • Evaluate potential adult migration barriers; • Assist in the future management and restoration of the system for the species and its recovery. DIDSON and video ~ Detected Apr 11 - Sept 8 Sturgeon found holding in 4 locations (see Figure 1) Majority identified as green sturgeon except at Bear River Estimate ~20-25 sturgeon total Possible passage impediment at Sunset Pumps at flows ≤ 170 cms (6000 cfs)    Egg mats ~ First time sturgeon spawning has been documented in the Feather River Sturgeon eggs (4) first collected on June 14 13 eggs total collected in less than a 2 week period Water temperatures were 16-17°C Several stages of development indicate multiple spawning events All collected at TAO Study Area = spawning confirmed Yuba River Fish Barrier Dam Pool * Bear River Thermalito Afterbay Outlet Pool (TAO) 2011 Methods Dual Frequency Identification Sonar (DIDSON) ~ an acoustic camera that provides high-definition sonar imaging of adults Roving boat surveys Feb 22 – Nov 3 Twice a week during spawning; once a month post-spawn Acoustic telemetry ~ Angled for green and white adult sturgeon (July 1st onward) Implanted VEMCO V-16’s surgically PIT - tagged (pre-dorsal fin) Acoustic telemetry ~ TAO: 2 green and 1 white sturgeon tagged Greens left Sept & Oct in <3 days when flows were stable White left during Dec in 7 days following flow decrease Verona Sacramento River Sunset Pumps • Egg mats ~ • Multiple sturgeon observed with DIDSON at TAO and Sunset Pumps; these 2 sites were sampled • Sampling conducted weekly April – June 30 • About 10 egg mats deployed per site • Checked and redeployed after 3-5 days • Note: 2012 study results completely different – only 3-6 adults!  * Photo by Thomas O’Keefe Conclusions Green sturgeon spawn within the Feather River in some years and it appears we will have to continue searching for answers in order to reach our objectives. Management decisions concerning future monitoring programs, operational changes of the facilities, and/or habitat enhancement within the lower Feather River are challenges we are beginning to overcome. Figure 1. Lower Feather River and the Oroville Facilities