Humboldt Bay supplies the entire West Coast with an outsized number of oyster seeds, making it arguably the most important place in California for oyster production. Climate change could threaten that.Warming waters — under the Representative Concentration Pathway 8.5 projection, Humboldt Bay is expected to heat up by an average of 3 degrees Celsius over the next 70 years — introduce new disease vectors that could wreak havoc on local oyster farmers, but their concerns are more immediate. As Eureka and Arcata become increasingly developed and the Humboldt Bay Harbor, Recreation and Conservation District builds an offshore wind terminal, oyster companies are wary of the potential impacts on water quality and plankton productivity.“We’re all for wind development, but there are environmental changes, associated dredging and other changes that are going to be associated with that project. There’s just still a lot of questions about what those impacts will be,” Gary Fleener, the science, education and policy director for Hog Island Farms, which has oyster nurseries and a farm in Humboldt Bay, said. “When I am referring to water quality, I want to make sure that it’s clear that I’m referring to it in the largest sense: water quality related to agricultural runoff, urbanization, and certainly development like shipping and wind energy.”Oyster production companies face a twofold issue: warmer waters induced by climate change could have catastrophic impacts on local farms but the offshore wind effort meant to combat climate change’s impacts presents several known and unknown impacts that could end up degrading local water quality.The harbor district is conducting several studies, including a measurement of the specific short-term water quality impacts of offshore wind terminal construction. Drafts of the studies should be made public by May 2025, Rob Holmlund, the harbor district’s development director, said.“I think it’s pretty safe to forecast that, in the long term, there won’t be impacts to water quality because of the project, but during the construction period, there’s dredging and there’s a water construction, but there are very tight regulations about turbidity, what you can do during construction and what you cannot do, and the times of year that you can do in-water construction,” Holmlund said. “Between all of the environmental regulations that already exist and our efforts to minimize water quality impacts, it’s not something I’m really worried about, but I do want to take the company’s concern seriously, so we’re doing extra studies.”Aquaculture companies operating in Humboldt Bay have been meeting with the harbor district every other month for roughly a year, which Holmlund said allowed the district to hear concerns and identify areas of improvement. One such concern, Holmlund said, was disease infiltrating the bay.Ostreid herpesvirus, a disease deadly enough to induce die-offs among oysters, was recently found in the warming ocean waters near San Diego. The disease thrives in water at about 15 degrees Celsius, which Humboldt Bay is expected to reach under the RCP 8.5 projection. In an April symposium, Northern Hydrology and Engineering civil engineer Jeff Anderson estimated that by 2095, the waters in Humboldt Bay will have heated from an average of 13 degrees Celsius to 16 degrees Celsius.If the disease emerges in Humboldt County, the farms might be hit hard, but oyster seed facilities — baby oysters grown in a hatchery resembling an aquarium — might fare better. Fleener said robust biosecurity measures at the hatcheries significantly alleviate his concerns about introducing disease vectors; measures taken because Humboldt County supports the entire West Coast with oyster seed.However, the existence of rules and regulations doesn’t mean slip-ups never happen. In early November, golden mussels — an invasive bivalve native to eastern Asia — were found in a reservoir near the Port of Stockton despite laws mandating inspections of ballast waters before they’re discharged into local waters.“Those regulations failed, so it just points to the need to do a much better job of considering how to limit that risk as we’re increasing vessel traffic related to the offshore wind industry,” Jen Kalt, executive director of Humboldt Waterkeeper, a local environmental advocacy group said.Given Humboldt Bay’s salinity — generally incompatible with the freshwater living requirements of golden mussels — Fleener said the area’s aquaculture companies are not particularly concerned about the species colonizing local waters.Washington state is the largest shellfish producer in the nation, but much of its seed is supplied by Humboldt Bay companies, which altogether sell about 10 million oysters per year and net $6 million in sales, according to harbor district estimates.Keep Reading
