September quiet settled over Katama Bay this week, as a handful of sailboats scudded in and out of the harbor. It was quiet too on the twelve oyster farms scattered across the broad saltwater bay that lies at the eastern end of Edgartown.
The oyster farms were shut down suddenly on Monday by state health and fisheries officials following an outbreak of the bacteria Vibrio parahaemolyticus. The outbreak appears to be small and confined to three cases where people became ill from eating oysters, and later recovered. And thanks to a tracking system used for farmed oysters, newly adopted this spring, state officials said they are confident they will be able to precisely track the contamination to its source.
To date this much is known: the bacteria that caused illness in the three cases came from Katama Bay oysters. Vibrio is a bacteria that occurs naturally in saltwater but can become a pathogen that multiplies and causes illness when it is in conditions that are too warm.
Beyond that the variables are numerous. Shellfish experts say outbreaks can occur for a variety of reasons. Sometimes they are traced to warm water which fuels an increased presence of the bacteria, but contamination can also occur due to improper handling at any point along the production chain, from the farm to a wholesaler to a retailer to a restaurant or caterer. In this case, though consumers were sickened by oysters eaten at two food establishments, the restaurants have been exonerated and the precise source of the contamination has yet to be disclosed.
“It’s a little bit of a detective story to figure it out,” Rick Karney, longtime director of the Martha’s Vineyard Shellfish Group, told the Gazette early this week following the closure.
“We recognize the impact these actions have on many of our local businesses, and we do not take them lightly,” state public health and fisheries officials said in a press release about the closure.
But the impact is potentially large, and it is urgent that the state move quickly to solve the mystery.
In the short term the closure of the largest and most productive area of farmed oysters on the Vineyard is a discouraging setback for the burgeoning young shellfish aquaculture industry on the Island. It comes just as the industry has gotten its sea legs following years of experimental work among small growers and a series of state grants that gave a boost to the efforts. Oyster farms have grown into a significant business, with more than five thousand bushels harvested from Katama Bay last year at an estimated value of more than a million dollars. Moreover, oyster production has a secondary benefit in that oysters are effective in reducing polluting nitrogen in our ponds.
More than once in recent years Mr. Karney has called the Vineyard the Napa Valley for shellfish. And with good reason. Clean, circulating saltwater ponds and bays such as Katama Bay provide excellent growing environments for hardshell clams, bay scallops and oysters.
Public confidence in the safety of oysters is imperative to sustain this nascent industry. Given the care with which the industry is now regulated, it should be possible for state officials to pinpoint the cause of what appears to be a very small outbreak of a naturally occurring bacteria. Assuming the source can be identified and the cause corrected quickly, this episode will quickly fade.
The value of a new industry like oyster farming to a community that has seen most of its fisheries disappear one by one is hard to overstate. It is not unusual to face setbacks when trying something new, and we are hopeful that this incident will simply serve to make everyone connected with this promising Island enterprise that much more careful. The sooner the facts are laid out and measures are taken to prevent a recurrence the better for farmers, purveyors and consumers alike.