Red Tide Prompts Limited Shellfish Closures

by Alan Pollock

            CHATHAM — The Massachusetts Division of Marine Fisheries last week ordered large portions of the Massachusetts coastline closed to shellfishing because of an outbreak of paralytic shellfish poison, or red tide.

            As of June 26, Pleasant Bay and Chatham Harbor were closed to the taking of all shellfish except mussels.  A large stretch of the east-facing shore from Nauset Inlet south to Nantucket was open to the harvesting of most shellfish, with the exception of ocean quahogs, whole sea scallops, surf clams and moon snails.

            The closure remained in effect at The Chronicle’s press time Tuesday afternoon, but could be modified by state regulators at any time.  Updated information will be posted on Chatham’s town website.

            Shellfish Constable Stuart Moore said shellfish taken from Stage Harbor and South Beach had been extensively tested, and showed no evidence of the red tide toxin.  But Moore said concerns about red tide have already caused a decrease in shellfishing.

            “Unless they hear or see otherwise through posted signs at any particular shellfishing area, then that area is safe,” Health and Environment Director Dr. Robert Duncanson said this week.  No closures were in effect along the Nantucket Sound shoreline. 

            Duncanson said people can be confident that shellfish in local stores and restaurants has come from approved areas and is safe to consume, he said.  Red tide also causes no public health threat to swimmers or boaters, he added.

            In 2005, an outbreak of red tide caused state officials to close productive shellfish beds for more than a month.  The outbreak caused local shellfishermen to lose an estimated $1.7 million.

            “So far, at least, the situation is not as bad as it was in 2005,” Duncanson said.  As of early this week, a complete closure was in effect from the New Hampshire state line south to the Cape Cod Canal, but Cape Cod Bay, most of the east-facing shore, and most of the remainder of the state’s shoreline was unaffected.  Though it is difficult to know for sure, Duncanson said it is possible that the closures are close to peaking—or have already peaked—and more openings will be forthcoming.

            But that could change if atmospheric conditions become more favorable for the red tide phytoplankton.  Specifically, the organisms thrive during warm temperatures and heavy rainfalls, which reduce the water’s salinity slightly.  Onshore winds could also cause the toxin to come ashore, Duncanson noted.

7/3/08