Dan Devereaux, owner of Mere Point Oyster Co. in Brunswick, heads out to his company’s oyster-rearing floats. Maine shellfish harvesters are hoping to make up for a longer-than-usual closure of harvest sites due to a biological toxin associated with red tide. The closure stretched for three months in parts of southern Maine and has only recently been lifted. JOHN EWING/Portland Press Herald

Maine shellfish harvesters hope to make up for a longer-than-usual closure of harvest sites caused by the biological toxin known as red tide.

Maine’s Department of Marine Resources routinely posts closures every year that affect clam, mussel and oyster flats up and down the state’s coastline. This year’s closure stretched for three months in parts of southern Maine, nearly three times as long as the normal four to five weeks, and only recently was lifted.

“We don’t have any specific indication of what caused the longer red tide season in southern Maine other than noting a large bloom offshore Down East earlier this summer which correlated with the longer season,” said Jeff Nichols, DMR spokesman.

Although red tide, which causes paralytic shellfish poisoning, or PSP, is not harmful to shellfish, the toxin can be harmful and even fatal to humans, hence the need for closures. PSP symptoms include numbness and tingling of the face, arms and legs, followed by headache, dizziness, nausea and muscular incoordination. Severe poisoning can cause muscle paralysis and respiratory failure.

A marine scientist who used to run the monitoring program for the state said she’s not convinced that levels of toxin, which is produced by the phytoplankton Alexandrium, are any higher.

Darcie Couture, who left the department in 2012 and now runs her own testing lab in Brunswick, said the state conducts far less testing for red tide than it used to and instead orders closures on a precautionary basis.


“It is easy to protect public health – if everything is closed to harvest, then there is no risk to public health,” Couture said. “However, as far as balancing that goal with responsiveness to industry needs, this year seems to have been an epic management failure.”

Nichols did acknowledge that since 2012, the state has relied more on precautionary closures, which require fewer testing sites. In 2012, DMR sampled 328 stations. So far this year, there have been 158, or less than half. Tests are done weekly from March through October.

The state’s new approach means that shellfish zones are closed at the first sign of toxins rather than when toxins exceed a certain level. It’s complicated, though, because toxin levels can spike from week to week.

“Precautionary closures may be made if there are elevated shellfish toxin scores that have not reached the regulatory limit based on a lot of risk factors: phytoplankton trends, current phytoplankton concentrations, weather forecast, sampling frequency and scores at nearby shellfish stations,” Nichols said.

Couture, though, criticized DMR as “ill-equipped to handle fine-tuning closures based on actual shellfish data, because the sampling program is structured differently now than it was prior to 2012.”

“It still seems very hard to explain away the fact that the DMR had longer closures in place this season than during either of the ‘disaster declaration’ years (2005 and 2008),” she said.


Nicole Twohig is the development coordinator for Quahog Bay Conservancy in Harspwell, which is a nonprofit focused on protecting the ecosystem but also harvests under the brand name Snow Island Oysters.

“We were shut down for about two months, which means we weren’t able to sell,” she said last week. “So that’s a loss of income for us, but the oysters are still there growing. When the closure is lifted, the oysters are bigger than we normally sell so the market is smaller.”

The ideal size, she said, is between 2.5 inches and 3.5 inches.

Twohig said she doesn’t fault the state. It’s doing the best it can. But she, too, wonders whether there are enough resources to manage a burgeoning industry.

“DMR does a really fantastic job regulating the industry for how understaffed they are,” she said. “But people were definitely starting to be concerned once we got to two months,” Twohig said. “You plan for some closures, but if this was my sole income, I would definitely be panicked.”

Nichols said he doesn’t view it as a resource problem. He said biotoxin monitoring and management is conducted by nine DMR staff members, five contract employees and 30 or so volunteers. He said funding is actually more stable now. Contract positions used to be funded with federal disaster relief dollars, which ran out. Now they are part of the General Fund.


Dan Devereaux of Mere Point Oyster Co. in Brunswick also didn’t fault the state and said the task of monitoring for toxins is “a tall order.” But he said he’s noticed a shift in how the closures have happened. He said in years past, red tide used to be more surgically monitored, which had less of an impact on commerce.

“Closing a big area is the safest thing to do, but how do you balance the impact on harvesters?” he said.

The clamming industry has been affected less because their location makes them less susceptible to the biotoxin. A representative from the Maine Clammers Association did not return messages left by a reporter.

Larger shellfish harvesters, known as leaseholders, can ask permission from the state to conduct their own weekly testing, at their expense. Many do, and if they come back clean, the leaseholders can harvest.

But smaller harvesters, known as limited purpose aquaculture sites, or LPAs, don’t have that option.

There are about 125 leaseholders and nearly 600 LPAs operating in Maine.


“The state takes a conservative approach to this, rightfully so, but it does hinder a lot of small farms, which can’t test their products,” Devereaux said.

Red tide is an annual occurrence in Maine, but there are other toxins that require monitoring as well.

Last year, the state was forced to close large sections of the Down East coast because of a toxic algae bloom called pseudo-nitzschia, a single-cell organism that can bloom unexpectedly and make domoic acid, a dangerous biotoxin that may cause amnesic shellfish poisoning, or ASP.

That bloom also led to a rare recall of clams and mussels in two consecutive years.

In addition to biotoxin monitoring, the state regularly tests for bacteria, which also results in periodic closures of shellfish harvesting areas.

The Department of Marine Resources lists all closures on its website in the form of complex legal notices. More information is available at https://www.maine.gov/dmr/shellfish-sanitation-management/closures/psp.html.

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