‘Unprecedented’ Red Tide Taints New England Shellfish

The worst toxic red tide in a generation is contaminating dozens of major shellfish beds in New England, prompting fishery closures from Maine to Nantucket, where clams, mussels and bay scallops are a coastal community’s commercial lifeblood.

An unusually intense plankton bloom more than 30 miles wide in places continued to spread Saturday, driven by wind and currents into areas that had never known such infestations.

The outbreak may peak in a week, officials said. It may be a month or more, however, before the region, which exports quahog clams and other seafood around the world, can safely resume shell-fishing operations.

Toxins from the algae quickly become concentrated in the shellfish, making the shellfish poisonous to eat.

“In terms of the region, this red tide is unprecedented,” said Don Anderson, a specialist on red tides and harmful algae blooms at the Woods Hole Oceanographic Institution on Cape Cod, Mass. “This is a huge area that is affected.”

In Nantucket Harbor, the level of toxin jumped to four times the legal limit almost overnight last week. Massachusetts officials closed island shellfish flats Friday.

On Saturday, town officials in Chatham at the southeast tip of Cape Cod, where fishermen harvest about $4 million worth of shellfish every year, finished closing all local waters for the first time in 20 years.

“This stuff can be lethal,” said Chatham Shellfish Constable Stuart F. Moore, who patrols the town’s 63 miles of coastline with eight part-time deputies. “My concern is for all the guys who are looking to be out of work for a long while.”

In nearby Sandwich -- the oldest town on Cape Cod -- on the northwest corner of the peninsula, officials braced for their first red-tide warnings in memory.

Overall, concentrations of single-celled algae are the highest measured since 1972, when an outbreak closed every shellfish bed in New England as a precaution.

But some areas set new records last week.

“The cell count we are seeing, especially in Massachusetts and Cape Cod bays, are often a factor of 10 and a factor of 20 higher than anything we have seen,” Anderson said.

Some spots are so saturated that a single plate of steamers or sauteed scallops from the area could kill a diner.

No one has reported food-related illness so far, however, a fact that Anderson attributed largely to state officials’ speed in closing infested shellfish beds.

Such seafood as crab, lobster, shrimp and fish is not affected, nor are any shellfish products currently on the market, Massachusetts marine fisheries officials said last week. Only shellfish that filter seawater for food can build up dangerous concentrations of toxin in their meat.

Algae blooms are a natural occurrence in the coastal waters of California and New England, often blamed for fish kills or noxious fumes.

The red tides have become more common in recent years, fed by pollutants flushed down rivers and in storm-sewer runoff, environmental specialists said.

Most of these microorganisms are not toxic, but some species found in New England waters, such as the Alexandrium algae in the current outbreak, are poisonous enough to lay low a whale. Indeed, a 1987 outbreak in Cape Cod Bay killed 19 humpbacks.

Woods Hole scientists think this recent outbreak resulted from natural events in the Gulf of Maine earlier this year. Heavy snows and torrential spring rains lowered seawater salinity and created conditions ideal for germinating dormant cysts in the sediment of the Gulf of Maine. More fresh water entered the gulf this year than in the last decade, scientists said.

Then two consecutive ocean storms from the northeast herded the growing microorganisms into the areas of shell fisheries, concentrating them along the coastline.

Relatively balmy weather ever since has fostered their explosive spread.

“When this is all said and done, everyone will be pointing fingers about why this was such a big event,” Anderson said. “Was this all meteorology; was this a pollution story; are there other factors?”