Species / Background
The anadromous Green Sturgeon (Acipenser medirostris) occurs along the west coast of North America from Alaska to Mexico and is listed as Threatened under the Endangered Species Act (ESA) in the southern part of its range. The ESA-listed southern Distinct Population Segment (sDPS), as well as the non-listed northern DPS, is encountered incidentally in state, federal, commercial, and recreational fisheries. Fisheries bycatch is a known threat to Green Sturgeon and not permitted in any state or federal fishery. Although most incidental captures are released alive, sublethal and lethal effects as a result of incidental capture and handling may have negative impacts on Green Sturgeon populations in California waters.
Monitoring & Research Needs Identified
To begin assessing these potential threats, two fundamental issues need to be investigated to understand potential impact of commercial trawl fisheries on the sDPS Green Sturgeon population: 1) the rate of recapture of the same individuals (to inform bycatch estimates), and 2) post-release mortality. In August 2014, the National Marine Fisheries Service (NMFS) held a workshop with the California halibut trawl fishermen, NMFS observers, and the Department of Fish and Wildlife (CDFW) to examine the interaction between the Commercial Halibut Trawl Fishery and Green Sturgeon, and to devise a cooperative research strategy to evaluate post-release impacts on Green Sturgeon in the fishery. Cooperative discussions during this workshop lead to the “Satellite Tagging Research Project”.
Satellite Tagging Research Project
Presently NMFS observers (with the West Coast Groundfish Observer Program) and fisherman working with CDFW staff are deploying “state of the art” satellite tags on Green Sturgeon encountered during normal halibut trawl fishing operations off the central California coast. For each Green Sturgeon tagged and released, data on tow characteristics and the fish (e.g., length, estimated weight, condition, genetic sample) are being taken to evaluate how post-release impacts may differ over the range of normal fishing conditions and fish sizes. Through July 2016, 72 satellite tag deployments occurred in the Gulf of the Farallones and through extensive public outreach, 28 tags (REWARD POSTER) have been recovered for data analysis and redeployment. This recovery effort has allowed this project to determine behavior of the tagged fish, including movement that will be used in the modelling efforts to understand this complex bycatch question.
NMFS and CDFW staff will continue to work closely together for collection of additional data, information, and analysis. These efforts will be coordinated with the fishermen engaged in the study.
Partners and Contacts
- California Department of Fish and Wildlife
- National Marine Fisheries Service, Long Beach
For additional information contact Russ Bellmer, CDFW Fisheries Branch, Russ.Bellmer@wildlife.ca.gov, Susan Wang, NMFS, Susan.Wang@noaa.gov.