State genetic labs confirm golden mussel in Bay‑Delta; agencies ramp up eDNA surveillance
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Summary
Department of Water Resources and partner labs confirmed Limnoperna fortunei (golden mussel) in the San Francisco Estuary in October 2024 and reported coordinated eDNA/qPCR surveillance and a planned SENTRI early‑warning program combining targeted qPCR and metabarcoding.
Sarah Stinson (Department of Water Resources genetic monitoring lab) described rapid interagency confirmation and scalable genetic monitoring following detection of the invasive golden mussel (Limnoperna fortunei) in October 2024.
Stinson said field crews first noticed an unidentified mussel at a Port of Stockton check station on Oct. 17; visual identifications and tissue Sanger sequencing were quickly corroborated by UC Davis and CDFA labs. DWR initiated qPCR testing (Pia et al. assay) and has optimized protocols with CDFW to increase sensitivity to single veliger detections. She said TONET composite net samples and targeted water samples have been processed; specificity testing confirmed the qPCR assay does not cross‑amplify DNA from native Delta mussels.
The lab is sharing confirmed results with partner agencies and CDFW maintains a public map plotting physical detections and confirmed eDNA positives across the state and down the State Water Project toward Southern California. Stinson said the mussel is now widely detected in the estuary and has moved downstream via water‑project connectivity to southern sites.
To improve early detection and preparedness, DWR is launching SENTRI — a surveillance program that will combine targeted qPCR for high‑priority invasive species and untargeted metabarcoding (metabarcoding of archived and new samples) to detect previously unknown arrivals. Stinson urged interagency cooperation, data sharing and use of archived samples for retrospective detection, and asked attendees with archived Port of Stockton samples to contact DWR for retrospective analysis.
Questions focused on mitigation options (difficult to eradicate; localized infrastructure treatments like hot‑water flushing exist but are context‑limited), spatial reporting anomalies in publicly posted coordinates, and seasonal patterns in veliger production. Stinson recommended early, widespread eDNA surveillance and interagency coordination to maximize detection and response options.
