Chris Nash, DES: 603-568-6741 or (603) 559-1509
Jane Vachon, NHF&G: (603) 271-3211
May 8, 2008                

Atlantic Coast and Hampton Harbor Shellfishing Closed Because of "Red Tide"

CONCORD, N.H. -- To protect the public from the possible consumption of contaminated shellfish, officials from the New Hampshire Department of Environmental Services (DES) and the New Hampshire Fish and Game Department have closed New Hampshire's Atlantic coastal waters, and the waters of Hampton/Seabrook Harbor, to the taking of all species of molluscan shellfish (mussels, clams and oysters) until further notice.  This action is in response to elevated levels of Paralytic Shellfish Poisoning or PSP, commonly known as "red tide," detected in blue mussels collected from the Isles of Shoals and from Hampton/Seabrook Harbor.

"Red tide toxicity levels are increasing right now, in both offshore and near-shore waters," said Chris Nash, Shellfish Program Manager for DES. "It is too soon to know how severe this algae bloom will be, or how long it might last." He noted that weekly sampling will continue from now until October. 

Blue mussels collected from Hampton/Seabrook last week showed low toxin levels, but samples collected this week exhibited toxin levels above the mandatory closure threshold of 80 micrograms of toxin per 100 grams of shellfish tissue.  Blue mussels from Star Island, Isles of Shoals, are also exhibiting high toxicity values.

Other New Hampshire shellfish harvesting areas, including the oyster beds around Nannie Island and Adams Point in Great Bay, were temporarily closed last week because of heavy rainfall, and will remain closed until additional red tide and bacteria tests are completed.  Officials from the New Hampshire Department of Environmental Services and the NH Department of Health and Human Services/Public Health Laboratory expect to complete this week's shellfish tissue testing by Friday, May 9, 2008, at which point a decision on whether or not to reopen Great Bay and Little Bay to harvesting will be made.  Changes to the open/closed status of shellfish waters will be announced on the Clam Flat Hotline (1-800-43-CLAMS) and on the N.H. Fish and Game website at

The nature of red tide blooms varies from year to year, according to Nash.  A red tide bloom in 2005 was the most widespread and toxic event on record for New Hampshire waters, while the past two years experienced less-severe events, characterized by high toxicity in the offshore Atlantic waters and lower levels of toxin along the beaches.  It is too soon to know what the nature of this year's bloom will be, although toxicity in Hampton/Seabrook is appearing earlier than in previous years.

Red tide is a condition in which filter-feeding molluscan shellfish such as clams, oysters and mussels accumulate a potent neurotoxin produced by a naturally occurring marine algae.  Ingesting the toxin is potentially fatal to humans, and cooking does not make contaminated shellfish safe for consumption.  For more information, consult the NHDES Shellfish Program website at

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