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Chris Nash, DES: 603-568-6741 or (603) 559-1509      
Liza Poinier, Fish and Game: (603) 271-3211
May 19, 2011

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.

“Toxicity levels are increasing right now, in both offshore and near-shore waters, because of a ‘bloom’ of red tide, which is toxic algae,” said Chris Nash, Shellfish Program Manager for DES. “It is too soon to know how severe this red tide bloom will be, or how long it might last.” He noted that additional sampling will be necessary to track the severity and duration of the bloom.

Nash emphasized that the closure affects those who dig their own shellfish, but it remains OK to eat shellfish from a reputable dealer or restaurant. “These shellfish have been sourced from shellfish beds that recently tested negative for red tide and other contaminants.” For more information on red tide, see the Red Tide Resource Center at

Blue mussels collected from Star Island, Isles of Shoals last week showed low red tide 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 collected from Hampton/Seabrook Harbor this week are also exhibiting high toxicity values.

Other New Hampshire shellfish harvesting areas were temporarily closed earlier this week because of heavy rainfall, and will remain closed until additional tests are completed. Officials from the New Hampshire Department of Environmental Services and the N.H. Department of Health and Human Services/Public Health Laboratory expect to complete this week’s shellfish and seawater testing by Friday, May 20, 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. Significant blooms and shellfish toxicity occurred in New Hampshire waters in 2005, 2008, and 2009, while 2010 showed a relatively mild bloom with low toxicity.

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. Visit

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