Eel River Ba'm (Green Sturgeon) Project
Stewards of Natural Resources
The Wiyot Tribe is continuing to develop its capacity to renew its traditional role as stewards of its natural resources. We were awarded grant funds through the National Marine Fisheries Service (NMFS)/National Oceanic and Atmospheric Administration (NOAA) Species Recovery Grant to Tribes to complete a three-year study of Eel River ba'm, green sturgeon (Acipenser medirostris). The Wiyot Tribe, with technical assistance from Stillwater Sciences, is in the perfect position to successfully investigate green sturgeon in the Eel River and fill a critical data gap.
The goal of this project is to determine the current status and population of origin of North American green sturgeon in the Eel River. Green sturgeon in the Eel River comprise one of the most prominent data gaps for North American green sturgeon given that the Eel River is one of the larger rivers in California and had an apparently large and important historic spawning run. Ambiguity exists in terms of the current status of green sturgeon in the Eel River with official designations considering the spawning run lost and yet sightings still occurring annually.
According to NOAA’s recovery planning document for southern Distinct Population Segment (DPS) green sturgeon, “In order to establish a recovery plan for the species, the current status of that species must be understood.” This project will greatly improve that understanding by investigating one of the best potential unrecognized spawning runs. For whatever green sturgeon that still spawn in the Eel River, it is important to determine if they are northern DPS, as presumsed without evidence, or if they are southern DPS, or a mix. All possible outcomes would be significant: 1) if they are northern DPS then this would add a third spawning river to that population besides the Klamath and Rouge rivers; 2) if they are southern DPS then that would add a vital second spawning population besides the Sacramento River, with important implications for resiliency; and, 3) if they are a mix, then it would be the first documented mixed spawning run.
Population of Origin
In addition to determining the population of origin, it’s important to document spawn timing and location, which can allow for a more accurate assessment of potential threats to successful reproduction and recovery in the Eel River. Another question to be answered is if the Eel River estuary, both the riverine and marine portions, are being used as rearing and feeding habitats for one or both DPSs of green sturgeon similar to nearby Humboldt Bay (mixed), or the Umpqua River estuary (northern DPS only), or the Klamath River (mixed in marine estuary, northern DPS only in riverine estuary).
The objectives of this project are to:
- Determine the presence, timing, and locations green sturgeon spawning and holding in the mainstem Eel River
- Determine the population of origin (southern DPS vs. northern DPS) of these fish
- Determine the summer residence of green sturgeon in the Eel River estuary (riverine and marine)
The project area will be from the confluence of the Middle Fork and mainstem at river mile 120 (Dos Rios) to the Pacific Ocean and the near shore marine portion of the estuary. It is important to conduct this study over a consecutive three year period to have an adequate baseline of data to meet the objectives given the spawning periodicity of green sturgeon.
Specific activities will include:
- Review of background scientific information and tribal oral histories and traditional ecological knowledge
- Assess habitat availability and limitations by cataloguing pool depths and gathering available water temperature and flow data
- Conduct a presence and enumeration survey on the mainstem Eel River using a mobile DIDSON sonar camera (192 river kilometers)
- Identify population(s) of origin using genetic analysis of any eggs collected with artificial substrate mats placed in likely spawning areas identified during the mobile DIDSON survey
- Monitor for individuals tagged elsewhere by installing a sonic receiver detection network at strategic sites in the marine, estuarine, and riverine migration corridor
- Report and disseminate findings in a manner that protects sensitive green sturgeon spawning and holding areas