Humboldt Bay is 'a hidden gem' for oyster production

Humboldt Bay is one of the only places left on the West Coast where oyster seed can be grown and shipped across state and international lines, a distinction that has become the backbone of the region's shellfish economy. Local growers say the bay's rare disease‑free status is what keeps the industry alive as climate change, ocean acidification and fast‑moving pathogens reshape oyster farming from California to Alaska.

"It's kind of a hidden gem, Humboldt Bay," Justin Mojonnier, the director of science and technology for Hog Island Oyster Company, said of Humboldt Bay's importance in the oyster and shellfish industry. "People don't really realize it, but we're a huge shellfish nursery; we produce a ton of shellfish seed out of this bay, we have a long history of producing shellfish seed out of this bay. It's a really big part of the whole West Coast industry. I think last year we produced over 400 million shellfish seeds, so that's both oysters and Manila clams. A big chunk of the West Coast supply chain has lived part of its life in Humboldt Bay, and the only reason that we could do that is the disease-free status."

Hog Island entered the hatchery business decades ago after climate‑driven stressors such as warming waters, low pH and ocean acidification made seed unreliable elsewhere. That disease‑free certification is what allows seed to move legally across state lines. It also makes Humboldt Bay one of the only places on the West Coast where an oyster can complete its entire life cycle in the same water.

"55%-60% of California's total oyster production comes out of Humboldt Bay, so it's not just the seed, it's not just the nursery, but we were a huge portion of California's total market-ready shellfish production," said Mojonnier. "Humboldt Bay is really unique in the way that the bay is, so just its geography and hydrology, we have a ton of mud flats, but we also have a ton of flushing, and this creates a really unique environment where we have a diverse phytoplankton assemblage in the bay, and phytoplankton are what oysters eat. If you go out and you kind of look at an aerial shot of the bay, especially during summer, it's green, it's just teeming with life. It's truly a unique ecosystem."

But growers warn that the system is fragile. Increased vessel traffic from increased ship traffic or proposed industrial projects poses the greatest risk of introducing pathogens like Ostreid herpesvirus-1 (OsHV-1), a highly contagious, viral disease that specifically affects bivalve shellfish, most notably the Pacific oyster.

"Any kind of ships coming into the bay is a promise of economic activity. You see it with the heavy lift terminal proposed by the Harbor District, cruise ships coming in, ships, but they're all a risk or a vector for disease introduction, and that's a big concern with the shellfish industry," said Mojonnier. "Ballast water, hull fouling, we don't control where these ships come from. Once that bell is rung, you can't unring it."

Terry Sawyer, a founder of Hog Island Oyster Co., said the value of Humboldt Bay's shellfish industry is far greater than what shows up in state production numbers. Hog Island entered the hatchery business decades ago because climate‑driven stress of warming waters, low pH, and ocean acidification had made oyster seed unreliable across the West Coast.

Sawyer operates in both Humboldt Bay and Tomales Bay, where the OSHV‑1 variant already causes 40%–50% mortality in some groups. More lethal strains have devastated oyster industries in France and Australia and recently appeared in San Diego. Hog Island has spent more than 30 years developing disease‑resistant broodstock, a slow, multi-season process that requires exposing oysters to pathogens to test resilience.

"Humboldt Bay is a keystone location for seed production that supplies the industry from California to Alaska, and it's key to all the most like all of the larger companies, Pacific Seafood, like Taylor Shellfish, like Hog Island, and then all the ones up in the Northwest, we sell seed to everybody up and down the West Coast," said Sawyer. "If a disease shows up in Humboldt Bay, that link gets taken out," he said. "The industry would be in a very bad place."

Sawyer also raised concerns about increased vessel traffic from ships or proposed industrial development, which he said poses the greatest risk of introducing pathogens into the bay.

"You don't get every ship inspected. The more ships and the more complicated the hulls, the more chance of introduction," said Sawyer. "Hog Island employs more than 300 people, and losing Humboldt's disease‑free status would cost millions and ripple through families and communities. Seed from Humboldt goes to Hawaii, Alaska, Washington, Oregon and California."

Garrett Collins of Taylor Mariculture shares that fear. Taylor Mariculture supplies seed for about 90 to 120 oyster farms worldwide. Taylor Mariculture's operation relies entirely on raw, untreated bay water to raise seed shipped from hatcheries in Hawaii and Washington.

"We in the shellfish industry have to go through very rigorous testing to make sure that our product is healthy and be able to pass state lines for export, that's one of the biggest concerns for a lot of us in the bay now, is because we've had such a long high history of being able to export heat out of Humboldt Bay with our certificates showing that these animals are free and clear and healthy," said Collins. "If we lose that ability to export out of Humboldt Bay due to a bad pathogen test or a new disease agent that comes in, it's basically game over for our industry."

As Humboldt Bay weighs new industrial proposals, shellfish growers say the community must understand what's at risk.

"Our water quality is of utmost importance. Every time a foreign vessel comes in, it puts me on edge. Once a bio‑agent gets in here, you can't unring that bell," said Collins. "This bay feeds the whole West Coast. There's no viable way to grow shellfish next to heavy industry. We're stuck between a rock and a hard place."

If you go

What: Arcata Bay Oyster Festival

When: Saturday, 10 to 5 p.m.

Where: Arcata Plaza

More information: www.arcatabayoysterfestival.com

Maranda Vargas can be reached at 707-441-0504

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