HARPSWELL — A precautionary shellfishing closure remains in effect in many areas of Casco Bay after a toxin that can be lethal to humans was detected last week.

The ban prohibits fishing for mussels, clams, quahogs, oysters and carnivorous snails from the affected water until further notice. 

Domoic acid, the bio toxin produced by a micro algae known as psuedo-nitzchia, causes Amnesic Shellfish Poisoning. The illness results in gastrointestinal problems, and in severe cases can lead to permanent short-term memory loss, seizures, coma and death. 

The Maine Department of Marine Resources enacted the ban Dec. 5. It now includes areas from Dyer Point in Cape Elizabeth to Haskell Island in Harpswell, as well as a portion of New Meadows River between Brunswick and Harpswell. New Meadows was included in an extended ban put into place Dec. 8. 

Kohl Kanwit, public health bureau director of shellfish sanitation and management for the state, said the toxin was detected during routine phytoplankton sampling. Kanwit said his department conducts the sampling “at least weekly, sometimes twice a week,” and that it has no projection on when the ban can be lifted. 

Jeff Nichols, communications director of seafood marketing and business development at the Department of Marine Resources, said high levels of the toxin are what causes ASP. The federal statute to close shellfish harvesting is domoic acid levels of 20 parts per million. Last week, Freeport shellfish tests revealed 17 parts per million. 

“We characterize these closures as precautionary closures,” Nichols said. “(It means) levels in the shellfish and phytoplankton that have been tested in that area have not reached the level by law that requires closure, but they’re getting very close.”

Nichols added that notices of closures are posted on the department’s website, and also issued to each of the affected municipalities. 

Eric Horne, at-large councilor for the town of Freeport and vice president of Maine Oyster, said his farm has been lot-testing sections of products this week. Horne said his company only ships product once a week, and he is waiting on test results for this week’s crop.

As long as the samples come back clean from the Department of Marine Resources, Horne’s oysters are able to be sent out within 24 hours of testing, even during the ban. Horne added he still hopes the algae bloom will dissipate sooner rather than later. 

“For folks who aren’t on farms, for folks who are doing wild harvest, it’s more difficult for those guys,” Horne said. “It’s too bad because everybody should be able to get their product out.” 

Mark Green, owner of Basket Island Oyster Co. in Portland, said the 24-hour testing has also been helpful to his business in the wake of the ban, and that the state is “remarkably efficient” in getting the results back on time.

“So far (the samples) have come back totally clean, so it has not impacted us at all,” Green said. 

Robert Earnest of Chebeague Island Oyster Co. said his area has also been unaffected by the ban, since no one on the island is harvesting oysters this winter.

“We put all of our crop to bed for the winter in the second week of November, so it doesn’t affect us,” Earnest said. 

Some areas are still open in the Brunswick area, such as Longreach and Harpswell Cove, which Marine Warden Dan Devereaux said has allowed for roughly a dozen harvesters to continue working in his district.

Devereaux added, however, that the closure occurring in December has added an extra dimension of difficulty. 

“It includes pretty much all of the mudflats, at least that Brunswick has,” Devereaux said. “It’s close to the holiday season, and the full-time guys that rely on shellfish harvesting full time, 365 days a year are certainly hurting to some extent.” 

Paul Plummer, Harpswell’s harbormaster, echoed that sentiment. Plummer said while Harpswell is lucky it has not been as heavily affected by the ban as other places, town staff will be especially vigilant about monitoring poaching.

“The warden is going to be looking pretty hard as we get closer to the holidays, (he is) certainly going to be looking for poaching from out of town,” Plummer said. “It’s a bad situation so close to the holidays, people need to make money.”

Judy Colby-George, a member of the Yarmouth Shellfish Committee, said the time of year is not only unfortunate, but unorthodox.

“I just don’t think we know very much about why it’s happening now,” Colby-George said. “It’s a weird time of year to be closed.” 

Devereaux said though he can’t attribute the late-season bloom directly to ocean warming, it is a problem communities on the West Coast deal with more often than the Northeast.

“I think it’s just one of those things we’re going to have to deal with as the ocean changes,” Devereaux said. 

For more information and updates about the shellfish closure, visit the Maine Department of Marine Resources website.

Elizabeth Clemente can be reached at 781-3661 ext. 100 or eclemente@theforecaster.net. Follow Elizabeth on Twitter @epclemente. 

A shellfishing ban enacted by the Maine Department of Marine Resources  includes areas from Dyer Point in Cape Elizabeth to Haskell Island in Harpswell, as well as a portion of New Meadows River between Brunswick and Harpswell.