CHATHAM – Shellfish from Nantucket Sound are once again safe to eat.
Not that they weren't to begin with.
The state division of marine fisheries closed Nantucket Sound on Oct. 10, following closures in Mount Hope By and Buzzards Bay, due to a potentially toxic phytoplankton bloom. The type of algae in the bloom, pseudo nitzschia, can build up toxins in shellfish that can cause amnesic shellfish poisoning, which can cause a range of symptoms from vomiting to permanent neurological damage.
While tests carried out since then showed that the bloom contained the algae of concern, tests of shellfish meats only showed low levels of the domoic acid toxin. Most tests were negative, said Michael Hickey, DMF shellfish program manager.
The closure was lifted as of Monday at noon.
“The problem was we'd never experienced a bloom like this,” he said. When it began, the agency had no means to test shellfish and had to send samples to outside labs as far away as Florida. So the prudent thing to do for public health was to close” the entirety of Nantucket Sound to shellfishing, he said.
DMF eventually obtained kits that allowed screening of shellfish for the toxin. When those turned out positive, a sample was extracted and sent to the Bigelow Laboratory of Ocean Sciences in Booth Bay, Maine which could determine overnight the levels of toxins.
“This was definitely a learning experience,” Hickey said of the situation.
Locally, the closure had little impact. Morris Island marked the easternmost limit of the closed area, leaving the rich Southway, Outermost Harbor and all of Chatham Harbor open to shellfish harvesting.
“It was a good precautionary measure,” Shellfisherman Jamie Bassett, chairman of the town's shellfish advisory committee, said of the closure, “but because Chatham has some of the best products on the east coast due to the Atlantic flushing at Monomoy, we were not closed.”
Shellfish prices appeared unaffected by the closure, he added.
The bloom is still in the water, Hickey said, but at levels below that point at which they would be a concern. Because this particular variety of pseudo nitzschia can have such serious health impacts, it will become part of routine shellfish monitoring going forward, he said.
“We're going to continue to do some monitoring, but it made no sense to keep the closure on,” Hickey said.
Areas previously under seasonal closures, including Buck's Creek, Mill Creek, Taylor's Pond, Muddy Creek, Champlain Creek and Oyster Pond, remain closed.