Hard Clam/Northern Quahog
Hard Clam/Northern Quahog
Mercenaria mercenaria
Also Known As
Hard clam, Quahog, Round clam, Chowder clam
Quick Facts
Region
New England/Mid-Atlantic,
Southeast
About the Species
U.S. farmed hard clams are a smart seafood choice because they are sustainably grown and harvested under U.S. state and federal regulations.
Environmental Impact
Clams provide net environmental benefits by removing excess nutrients and improving water quality.
Feeds
Growing clams requires no feed – they filter phytoplankton directly from the water column.
Farming Methods
Clams are grown in tidal areas. They can be grown directly on the beach bottom or in mesh bags, trays, or pens that are secured to the bottom.
Human Health
Shellfish toxins and bacteria occur naturally in the environment and can cause foodborne illnesses. State and federal regulations require monitoring of farmed clams to ensure they are safe to eat.
Appearance
- Adult hard clams are just less than 3 inches, but can reach up to 5 inches.
- The shell is thick, grey to white in color, and has outer concentric growth rings.
- The inside of the shell is white with violet markings.
- Some hatchery raised clams have dark, zigzag stripes across the shell known as “notata”.
Biology
- Are of the shellfish family. Like oysters, mussels, and scallops they are bivalve mollusks, and have a hinged shell.
- Clams have slow growth rates and can live 12-20 years on average, and up to 40 years.
- Adults are sessile – they stay in one place – and inhabit both intertidal and subtidal areas.
- Clams burrow into the sediment, leaving only their siphons exposed to feed.
- Hard clams prefer saline water and cannot survive if the salt content is too low.
- Each female can produce between 1 and 5 million eggs during a spawning event.
Fishery Management
- Permitting for shellfish aquaculture is governed by federal, state and local governments.
- The federal agencies involved are NOAA, the Army Corps of Engineers, Fish & Wildlife Service, U.S. Department of Agriculture, the Environmental Protection Agency, the Food and Drug Administration, the Bureau of Ocean Energy Management, and the Coast Guard.
- Shellfish farms must adhere to federal regulations including those in the Magnuson-Stevens Fishery Conservation & Management Act, the Endangered Species Act, the National Environmental Policy Act and the Clean Water Act.
- Information on shellfish aquaculture permitting can be found in the Shellfish Growers Guide.
- A variety of shellfish aquaculture tools, including maps and models, are available to coastal managers. //
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Grilled tuna lemon with mayo. Credit: North Carolina Sea Grant/Vanda Lewis.