In his years working in the oyster business, Mark Wiegardt had never seen anything like it.
"It scared the bejeezus out of us," he said, speaking from the Whiskey Creek Hatchery in Netarts Bay, Oregon.
The thing that so frightened Wiegardt is invisible to the human eye. But its presence in the waters of the US Pacific coast has oyster farmers and scientists baffled, and threatens a shortage of the delicacy in oyster bars and delicatessens from Mexico to Canada, from Portland to Miami.
Vibrio tubiashii is a bacterium that kills shellfish at the larval stage. While it has come and gone sporadically since the 1960s, it took up residence on the US Pacific shoreline two years ago and has not gone away. Its presence led to the temporary closure of Whiskey Creek, one of the largest oyster hatcheries in the US, and has placed in jeopardy the business of others involved in the $111m (£57m) industry.
Mark Camara is a geneticist who works for the US department of agriculture in Newport, Oregon. He, like many in the tightknit scientific community in the Pacific northwest, has worked with Wiegardt to resolve the problems facing the industry.
Thanks to their efforts, including the introduction of a $180,000 filtration system, Whiskey Creek is now at 30-50% of its normal annual production of around 10bn oyster larvae.
"But between August and October we virtually produced zero larvae," said Wiegardt. "There's definitely going to be a ripple effect with this thing. We've told our customers, if you can find it somewhere else, get it."
Robin Downey, executive director of the Pacific Coast Shellfish Growers' Association, said the industry was confident that it would find a solution.
"We don't have a broad geographical picture," she said. "We don't know if this is a blip or a trend. It may be something that happens every 100 years."
Claudia Hase, an assistant professor at Oregon State University's college of veterinary medicine, said the problem seemed to be affecting not just oysters but other shellfish, including clams, geoducks - popular in sushi - fin fish and possibly shrimp. And it is spreading, with instances noted in Florida.
"It seems like it could be a huge problem," she said.
As for the cause, Hase hints at something that few want to articulate. "No one wants to admit it," she said. "It's very political." The suggestion is that climate change is a factor in the enduring presence of the bacterium.
Whiskey Creek Hatchery hopes to be back close to normal by next spring, if it can extend its filtration system, and if the system continues to produce results. But Wiegardt is concerned that the problems are merely a symptom of a larger malaise.
"We're pretty concerned about what is going on with the dead zones," he said. "Is that a connection to global warming? That's the consensus."