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

CONCORD, N.H. -- 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 to protect the public from the possible consumption of contaminated shellfish. 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 New Hampshire’s coastal waters and in Hampton/Seabrook Harbor and tributaries,” 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 early this week showed low toxin levels, but samples collected on Wednesday, May 25, 2022, exhibited rising toxin levels. Blue mussels from Star Island, Isles of Shoals, collected earlier this week also indicated the presence of PSP toxin.  

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. Repeated testing at these sites has shown no toxicity. 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. In cooperation with the New Hampshire Department of Health and Human Services’ Public Health Laboratory, 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 and the NH Fish and Game Red Tide Resource Center.