The state's Division of Marine Fisheries Thursday ordered the first Red Tide clam bed closure in Essex County this season — with the shutdown most of the beds from Manchester up through Gloucester, Rockport and Essex to the New Hampshire line.
Dave Sargent, the Gloucester shellfish warden, said he received a notice from the state Thursday shortly after noon.
He said there are about 100 commercial and between 300 and 400 recreational clammers in Gloucester, and about 500 to 600 acres of clam flats here in Gloucester.
The so-called Red Tide marine algae is poisonous, can cause paraletic shellfish poisoning, and can potentially be deadly to humans in extreme concentrations.
The toxins accumulate in the bodies of clams and other bivalves that flush seawater for nutrients.
The toxin does not, however, accumulate in lobsters and crabs, so eating these sea creatures even from waters with a confirmed persence of Red Tide is not seen as harmful.
The closure — at least for now — excludes Plum Island Bay, the Merrimack River and the Ipswich River. But otherwise no clamming is allowed while the toxic algae is present along the coast of the Great Marsh and the Annisquam River estuaries.
Testing is under way for Red Tide in the limited areas still open, according to Sargent.
When highly concentrated, the algae has a reddish color and can turns waters red, hence the name.
The algae appears in most oceans of the world and typically are generated in high concentrations by favorable conditions during the spring, which feature heavy rains, melting of snows and cool temperatures. The algae is pushed by water currents and winds and frequently are directed with these conditions into inshore clam beds.
Essex County and the coastline of the Great Marsh are the center of a $30 million industry.
The Red Tide can remain for weeks, and often compels local restaurants to buy from distributors in Maine and Canada, when local beds are closed.
In Essex County alone, the commercial shellfish industry and related businesses are estimated to generate $30 million in economic activity annually.
Red Tide closures have become a nearly annual occurrences in New England during the late spring and early summer. But they can be costly to area businesses.
An extended 2008 closure was estimated to cost $1.2 million in direct shellfish sales, according state economic figures.
A 2005 outbreak that lasted two months was the most damaging on record.
Richard Gaines can be reached at 978-283-7000, x3464, or at firstname.lastname@example.org.