Katama Bay oyster farms in Edgartown have been closed due to an outbreak of Vibrio parahaemolyticus (Vp), the Massachusetts Department of Public Health and the Department of Fish and Game, Division of Marine Fisheries announced Monday.
“The decision to close the beds was reached in consultation between DPH, DMF and the U.S. Food and Drug Administration,” a press release from the state agencies said. “We recognize the impact these actions have on many of our local businesses, and we do not take them lightly."
Katama Bay is home to a large area of oyster farms with 12 active independent oyster farming operations. Edgartown shellfish constable Paul Bagnall said yesterday about five million oysters are harvested in a year. Last year 5,500 bushels came out of the bay valued at about $1.1 million.
Katama oysters are served around the Island and in restaurants elsewhere, including in Boston and New York.
DPH has linked two cases of Vibrio illness to raw oysters consumed from this area, the state press release said. “In both cases, the people who consumed the oysters have recovered.”
Mr. Bagnall told the Gazette Monday that after the cases were tied to Katama Bay, the oyster farms were closed and any product recalled. Oysters purchased from Katama Bay from August 1 to Sept. 9 can be returned to the grant holders, he said. Harvesting oysters from the bay is prohibited at this time.
Mr. Bagnall said he expects the closure to last about four weeks. An investigation will take a careful look at the sources of the shellfish in the reported Vp cases, he said, and through a tagging system the oysters can be traced from where they were served to a middle man, if any, and finally to the harvester. Restaurants are also required to keep temperature records, the constable said.
There are logistical challenges to this process, Mr. Bagnall added, noting that sometimes people eat platters of oysters from a variety of places. For now he said there is confidence that the reported incidents trace back to Katama Bay.
A bacterial pathogen commonly found in warmer waters, Vibrio causes gastrointestinal illness, often with abdominal cramping, nausea, vomiting, fever and chills. Severe disease is rare and occurs more commonly in people with weakened immune systems. To prevent the occurrence of the bacteria, oyster harvesters must quickly refrigerate their catch.
According to the DPH, there have been 50 reports of confirmed Vp in state residents since May 31, 2013, with 31 of those cases linked to consumption of raw oysters from Massachusetts growing areas. In the same time period last year, the state said, there were 27 cases. Under federal regulations, the state is required to take action when shellfish are linked to an outbreak in two or more people. Vp also led to a shellfish bed closure and recall in Connecticut this summer.
Oyster beds in Plymouth Harbor, Kingston Bay and Duxbury Bay were closed in late August due to Vp. That was the first time a specific area was implicated in a Vibrio outbreak, the DPH said.
On the Vineyard, Mr. Bagnall said the closure might lead to stricter icing and harvesting regulations or closures of the bay when the water reaches certain temperatures. He added that the bacteria can be hard to prevent and that as New England oysters rise in popularity, there could be more frequent outbreaks.
“You can still be really careful every step of the way and per million servings there’s going to be one,” he said.“It’s a tough thing.” He noted that the thresholds for acceptable levels of the bacterium are extremely low, and that oysters are often served raw.
“I’m not very optimistic about harvesting next summer, but we’ll see,” Mr. Bagnall said.
On Monday afternoon, Martha’s Vineyard Shellfish Group director Rick Karney said he was just learning about the closure. To his memory, this is the first time there has been a reported case of Vp on the Vineyard.
Mr. Karney said he was surprised, noting that this summer was cooler than last, and thus the water should not have been warmer. But there was more rain, he added which can lead to more organisms and higher levels of bacteria in the water.
The impact on shellfish farmers would depend on the length of the closure, Mr. Karney said. While the summer is a big season for aquaculture, he said the holidays are also a busy time for sales.
Mr. Karney said Vibrio is a “ubiquitous bacteria” that is always in the water, but is present in higher numbers when water is warmer.
“There are a couple of different ways to look at it,” he said of the outbreak. One could be that there has been an increase in the natural occurrence of the bacteria in the water. Or, he said, there was a problem with handling that led to the outbreak.
He said the state has several safety precautions in place in case of an outbreak, with the closure being one of them. An investigation into the source is another one. “It’s a little bit of a detective story to figure it out,” Mr. Karney said.
Louie Larsen, who owns the Net Result fish market in Vineyard Haven, said Monday he had been calling restaurants that bought seafood from his seafood market telling them to stop serving the oysters immediately. The oysters can’t be destroyed, he said, and must be returned and accounted for per state guidelines.
“I feel bad for the guys who ship off-Island,” Mr. Larsen said, but he was thankful that this didn’t happen during the middle of the summer season. He estimated that the store sold about 2,000 oysters this weekend, most of them already consumed. He said the infected oysters did not come through his store.
“This is the first time we’ve ever seen it here,” the longtime fishmonger said, wondering about the recent rise in Vp. He said perhaps outbreaks were identified as food poisoning in the past.
For now, Mr. Larsen said he’s looking for new oyster sources. Because there have been outbreaks of Vp around the East Coast, he said, he is looking at bringing in Canadian oysters.