SALISBURY — The state's Division of Marine Fisheries announced yesterday it was closing shellfish beds across the region because of the presence of paralytic shellfish poison, an algae more commonly known as red tide.
Harvesting shellfish, including carnivorous snails and whole sea scallops, is prohibited in the waters, flats and tributaries in growing areas in Newburyport, Salisbury, Newbury, Rowley, Ipswich, Essex, Rockport and Gloucester. Sea scallop adductor muscles can still be harvested.
The ban does not include shellfish growing areas N2, N4 and N5. Those regions include the Merrimack River and Plum Island Sound — which consist of the majority of Newbury, Rowley and Ipswich — said Newbury shellfish constable Charles Colby.
The ban also extends to marine waters managed by Massachusetts and New Hampshire, including Hampton-Seabrook Harbor.
Shellfish include clams, oysters and mussels. Naturally occurring red tide algae can make shellfish toxic and potentially deadly should someone eat them. The toxin can affect the human nervous system and even cause fatal paralysis. No illnesses have been reported in Massachusetts.
For clammers around Greater Newburyport, the news doesn't immediately change things, as shellfish beds have been closed because of prolonged periods of rain, said Colby and Salisbury harbormaster/shellfish constable Ray Pike.
Pike said shellfish beds become off-limits should the region receive a quarter-inch of rain. Five days of dry weather must be recorded and shellfish tested before the flats can reopen.
Pike said red tide could be in the region for a prolonged period should wind conditions continue to draw the algae toward the riverbanks. Red tide algae floats along the surface and is pushed in different directions by wind.
"But I'm an optimist," Pike said.
It's been a few years since the region has been affected by an infiltration of red tide, Pike said.
New Hampshire shellfish program manager Chris Nash says the toxic algae could be a danger to those people who dig their own clams and harvest other shellfish. But, it's OK to eat shellfish from reputable dealers or restaurants, he said.
Officials say blue mussels collected from Star Island, Isles of Shoals, last week showed low red tide levels, but samples collected this week exhibited toxin levels above the mandatory closure threshold. Blue mussels collected from the Hampton-Seabrook Harbor this week also showed high toxin levels.
Last month, the Massachusetts Division of Fisheries closed part of Nauset Marsh, off Cape Cod, to shellfishing because of red tide, and that area was expanded Monday.
State public health officials are warning consumers not to eat shellfish recently harvested from the southern Nauset Marsh area between Orleans and Eastham on Cape Cod because it may be contaminated by the naturally occurring nerve poison.
The Public Health Department said earlier this week some shellfish harvested and sold from the Cape Cod area after April 29 could have absorbed the toxic plankton present in red tide.
Material from The Associated Press was used in this report.