The Massachusetts Division of Marine Fisheries (MarineFisheries) in cooperation with the City of Newburyport, is pleased to announce the reclassification and reopening of Joppa Flat in the Merrimack River estuary, to the Conditionally Restricted commercial harvest of soft shell clams (Mya arenaria) for depuration.   Recreational harvesting and harvesting for direct human consumption remains prohibited. 

Once considered among the top clam producing flats in Massachusetts, bacterial contamination had shut down this highly productive bed for over 80 years.  Keys to re-opening the area were improved water quality as well as a comprehensive management plan developed with the City of Newburyport. The restrictive state and local harvesting regulations will ensure clams harvested from the area are safe to eat.

Results of a Sanitary Survey of the area indicate rainfall triggers are intermittent and predictable episodes of bacterial contamination in excess of standards will occur.  Accordingly, the area will be closed to shellfishing for 5 to 7 days after rainfalls of greater than or equal to 0.25 inches. Rainfalls exceeding 1.50 inches or greater will result in longer closures subject to re-sampling. 

Under the “Conditional Restricted” nature of the reopening only the harvesting of clams by specially licensed individuals will be allowed.  Due to mild to moderate levels of bacterial contamination even during dry weather periods, all clams harvested must be “cleansed” (depurated) at the MarineFisheries Shellfish Purification Plant on Plum Island, Newburyport.  Soft shell clams and other bivalve mollusks become contaminated by filtering both harmless and pathogenic (disease causing) bacteria and viruses from seawater in the process of feeding and respiration.  Contaminated shellfish can transmit these organisms to people if the shellfish are eaten raw or under cooked.  To become safe for human consumption, these shellfish must first be purged of the harmful organisms to a level suitable for food purposes.

Only soft shell clams may be harvested by specially licensed Master and Subordinate diggers.  Longstanding regulations limit harvest in Conditionally Restricted Areas to weekdays only for Master Diggers and their employees, known as Subordinate Diggers, The Master buys the clams from subordinates at the landing site.  The clams are then placed in plastic boxes, loaded onto the Master Diggers truck and transported to the depuration plant on Plum Island via a prescribed route. 

Upon arrival at the Shellfish Purification Plant, the clams are placed on pallets, then lowered into one of nine, 3500 gallon tanks. The tank is filled with clean salt water from two 130' deep wells.  Depuration is actually a self-cleansing process.  The shellfish purge their digestive system of particulates as seawater is continuously re-circulated and sterilized by ultraviolet lamps.  Clams and tank seawater are tested daily for bacteria at the in-house laboratory. Typically, after 2½ to 3 days the shellfish are clean.  The clams are then returned to the Master Diggers who sell them to Massachusetts wholesale shellfish dealers for processing and/or resale.

The Merrimack River was once considered one of the nation’s ten most polluted rivers.  This reopening is due to concerted clean-up efforts begun over twenty years ago by local, state and federal programs and an aggressive re-sampling initiative by MarineFisheries. The reopening encompasses over 251 acres of the southeastern portion of the Joppa Flat, while the northwest section remains CLOSED and classified Prohibited as part of a closed safety zone around the Newburyport Wastewater Treatment Plant discharge.  Joppa Flat will join some 534 acres of Merrimack River estuary clam flats in Newburyport and Salisbury, reopened in 2006. 

Please contact the Newburyport Harbormaster & Shellfish Constable Paul Hogg for City requirements at 978-462-3746.  For further information on MarineFisheries requirements and regulations please contact: Jeff Kennedy at 978‑465‑3553 or Dave Roach at 978‑282‑0308.