Drakes Bay Oyster Co. Causing Alarming Amounts of Marine Vomit in Drakes Estero

A new scientific report released today reveals that the controversial Drakes Bay Oyster Company’s production of millions of non-native Japanese oysters is perpetuating “alarming” amounts of the highly aggressive and invasive “marine vomit” that threatens the ecological health of Drakes Estero marine wilderness area.

The study, prepared by Jude Stalker, an experienced Bay Area invasive species removal specialist, documented that Didemnum vexillum (Dvex or marine vomit) has infested the Drakes Bay Oyster Company's non-native oysters and oyster infrastructure. Alarmingly the marine vomit has invaded both dead and live eelgrass that exists on the floor of Drakes Estero. Dvex is considered to be a significant threat to the health of marine ecosystems because of its documented ability to spread rapidly, smother native flora and habitats, and thereby reduce the biodiversity of natural areas. Because eelgrass dominates the bottom habitat of Drakes Estero, the potential adverse impact from the existing Dvex infestation is substantial.

“The Drakes Bay Oyster Company’s operations and practices in Drakes Estero that are spreading marine vomit represent an undeniably dangerous threat to the native flora and fauna of Drakes Estero marine wilderness area and must stop immediately,” said Amy Trainer, executive director of the Environmental Action Committee of West Marin. “Despite awareness of the increasing Dvex infestation on its non-native oysters, the company has failed to take responsibility for or remediate this serious ecological disaster in the making,” Trainer said.

The report is based on a kayak survey of Drakes Estero and states that the amount of Dvex documented represents “a trend of increasing infestation” as well as a “new ability” of Dvex to spread onto eelgrass within Drakes Estero. Eelgrass is the critical base of the marine food chain that dominates the bottom habitat of Drakes Estero, and approximately 5-7% of California’s remaining coastal eelgrass is in Drakes Estero. Thus, the ongoing and future harm to numerous native flora and fauna that utilize eelgrass for food and habitat is cause for “serious concern” the report said.

The report notes that the “abundant population of Dvex observed on the DBOC infrastructure [oyster racks] provides a significant source of Dvex in both larval and fragmental form in Drakes Estero.” The Drakes Bay Oyster Company’s harvesting practices of pulling Dvex-infested hanging culture lines and tubes from the racks, transporting them on open barges, separating and cleaning the Dvex-ridden oyster shells on the dock and returning the fragmented Dvex colonies back into the water “are all likely facilitating the spread and persistence of this highly invasive species.”
Dvex colonies are aggressive and rapidly-spreading invasive marine organisms. In some cases, rapid expansions like the one going on in Drakes Estero cause significant changes in the natural community structure.

The report noted that Dvex research elsewhere concludes that the environmental and economic damage from an uncontrolled Dvex infestation is great. “This survey indicates an increasing potential for that outcome in Drake Estero.”

Research has shown that a rapid response to a Dvex infestation is essential to successfully manage and ensure its removal from a natural area. The report recommended the immediate removal of Dvex from all infested sources in the Estero, including infested oysters, infested oyster cultivation infrastructure, infested live and dead eelgrass, and any other infested natural substrate.

The California Coastal Commission ordered the company to deal with its marine vomit problem in February, but the company instead sued and has done nothing to date to address the issue. The Drakes Bay Oyster Company was denied for the second time a preliminary injunction to keep operating by the 9th Circuit Court of Appeals on September 3rd. Drakes Bay Oyster Company was removed from the Monterey Bay Aquarium’s Seafood Watch Partner list more than 3 years ago and is being supported by the Koch brothers funded Pacific Legal Foundation and Americans For Prosperity in its quest to commercialize Drakes Estero Wilderness. Today’s report comes on the heels of the Sonoma County Democratic Central Committees overwhelming support for Interior Secretary Salazar’s decision to allow Drakes Estero to run wild.