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For Immediate Release
June 28, 2019


Chris Nash
(603) 568-6741

Shellfishing ‘Red Tide’ Harvest Closure Extended to Great Bay and Little Bay

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 all New Hampshire coastal waters for the taking of all species of molluscan shellfish (mussels, clams, oysters) until further notice. This action is in response to rising levels of Paralytic Shellfish Poisoning or PSP, commonly known as "red tide," detected in blue mussels collected from several monitoring stations earlier this week.


“Red tide toxicity levels are rapidly increasing right now in the Gulf of Maine,” 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.


NHDES implemented a red tide harvesting closure on May 9 for the waters of Hampton/Seabrook and the Atlantic Ocean. Red tide levels have been closely tracked since that time in those waters, as well as in the recreational and commercial harvest areas of Great Bay and Little Bay. Blue mussels collected from Little Bay on late Wednesday of this week showed toxicity levels just under the mandatory closure threshold of 80 micrograms of toxin per 100 grams of shellfish tissue. This increase prompted a precautionary closure of shellfish harvest in Little Bay and Great Bay.


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