Joppa Flat in the Merrimack River Estuary Reopens for Commercial Clam Digging

Newburyport, Mass – The Massachusetts Department of Fish and Game and the Division of Marine Fisheries (DMF) announced that 250 acres of Joppa Flat in the Merrimack River estuary will be open for the commercial harvest of softshell clams by specially licensed commercial diggers.

“I am happy to credit the city of Newburyport and the staff of our Division of Marine Fisheries for the hard work that was necessary to open this area to commercial clammers,” said Department of Fish and Game Commissioner Mary Griffin. “Massachusetts’ soft shell clam harvest is worth five to six million dollars annually and the opening of Joppa Flat will benefit commercial shell fishermen in the area who rely on open and productive flats for their livelihood.”

The reclassification and reopening of the Joppa Flat allows the conditionally restricted commercial harvest of softshell clams (Mya arenaria). Under the restrictions, harvesting is limited to weekdays only and must be conducted by specially licensed diggers. The clams must be treated at the DMF depuration plant. 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.  Improved water quality and a comprehensive management plan developed with the City of Newburyport, has allowed the area to be reopened. The restrictive state and local harvesting regulations will ensure clams harvested from the area are safe to eat.

Rainfall will trigger episodes of bacterial contamination in excess of national standards. Accordingly, the area will be closed to shellfishing for five to seven days after rainfalls of 0.25 inches or greater. Rainfalls of 1.50 inches or greater will result in longer closures subject to re-sampling.

Softshell clams and other bivalve mollusks become contaminated by filtering both harmless and pathogenic, or disease-causing, bacteria and viruses from seawater during feeding and respiration. Contaminated shellfish can transmit these organisms to humans if the shellfish are eaten raw or under-cooked.

At the DMF Shellfish Purification Plant, the clams are placed on pallets and then lowered into one of nine 3,500 gallon tanks for depuration. Depuration is a self-cleansing process where the shellfish purge their digestive system of particulates in clean seawater; the shellfish are typically clean after two to three days at the plant.

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 20 years ago by local, state and federal programs and an aggressive re-sampling initiative by DMF. The reopening encompasses over 251 acres of the southeastern portion of the Joppa Flat, while the northwest section remains closed. Joppa Flat will join some 534 acres of Merrimack River estuary clam flats in Newburyport and Salisbury that were reopened in 2006.

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