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For Immediate Release
May 9, 2019


Chris Nash, NHDES Shellfish Program
(603) 568-6741

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

Concord, NH - To protect the public from the possible consumption of contaminated shellfish, officials from the New Hampshire Department of Environmental Services (NHDES) 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, 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 Hampton/Seabrook Harbor yesterday.


“Red tide toxicity levels are increasing right now in the Gulf of Maine and in Hampton/Seabrook,” said Chris Nash, Shellfish Program Manager for NHDES. “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 rising toxin levels. Yesterday’s sample was just above the mandatory closure threshold of 80 micrograms of toxin per 100 grams of shellfish tissue. Blue mussels from Star Island, Isles of Shoals, also exhibited high toxicity levels this week.


Other New Hampshire shellfish harvesting areas, including the recreational oyster beds around Nannie Island and Adams Point in Great Bay, and the commercial oyster farms in Little Bay, are not affected by this PSP closure. Furthermore, the red tide closure does not apply to the harvest or consumption of lobster, although state officials continue to advise consumers to avoid eating lobster tomalley, the soft green substance inside the lobster’s body. Officials from NHDES will continue to monitor seawater algae populations and shellfish toxicity levels throughout coastal New Hampshire and will implement additional closures as appropriate. Changes to the open/closed status of shellfish waters will be announced on the Clam Flat Hotline (1-800-43-CLAMS) and on the NH Coastal Atlas (


Red tide is a condition in which filter-feeding 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


Also see the NH Fish and Game Red Tide Resource Center at