Clams

Clams

Littleneck Clam, © Amadeo Bachar

At a glance

Eco-rating Mercury Omega-3s
+-Softshell clam
Best
Low

MORE ABOUT SOFTSHELL CLAM

Long an important food source in the Atlantic, the softshell clam was introduced to California waters from the Atlantic in about 1870 and gradually spread north to British Columbia. In England, the species is known as the Sand-gaper, and the Northeastern American Indians dubbed it the manninose. Its shell can grow up to 5 inches (13 cm) long.

Commercial Sources

Softshell clams are native to the western North Atlantic, from the sub-arctic to Cape Hatteras in North Carolina. They have been introduced into the West Coast of North America, from Alaska to California, as well as the Baltic, Black and possibly the Mediterranean Seas.

The main sources of softshell clams are the United States and Canada.

Capture Methods

Softshell clams come from coastal fisheries, not shellfish farms. They are primarily harvested with hoes and by handpicking. Additional types of fishing gear include rakes and dredges.

+-Butter Clam (farmed)
Best
Low

MORE ABOUT BUTTER CLAM

Butter clams are native to the protected bays and estuaries of the Pacific Northwest. They live on sand, shell and gravel beaches -- as much as 15 meters below the low-tide mark.

Commercial Sources

Butter clams are primarily produced in Canada and to a lesser extent in the United States.

Capture Methods

Roughly three-quarters of the butter clams harvested in the U.S. and Canada are wild and presumably taken by hand in the intertidal zone. The remaining quarter is farmed in nearshore shallow waters; the bottom is seeded with baby clams and then harvested after several years once they have matured.

+-Manila clam (farmed)
Best
Low

MORE ABOUT MANILA CLAM

Manila clams have been farmed for centuries in Japan, and they are becoming increasingly popular in the U.S. Manila clams are found throughout the temperate Pacific and typically live high in the intertidal zone.

Commercial Sources

Manila clams, native to Japan, are raised in huge quantities in China, Korea and Japan. The U.S. produces a significantly smaller quantity but does not appear to import large amounts of manila clams from any of the major producers.

Capture Methods

Manila clams are almost entirely farmed. Farmers in Washington State and British Columbia typically raise manila clams in nearshore shallow waters; the bottom is seeded with baby clams and then harvested with rakes after several years once they have matured.

+-Pacific geoduck (farmed)
Best
Low

MORE ABOUT PACIFIC GEODUCK

Found in the Pacific from southern Alaska to Baja California, the geoduck is noted for its extralong siphons that can reach up to 4 feet (1.2 meters) and may constitute half the weight of the animal (which can weigh 8 pounds and live up to a century). Most of the geoduck harvested in the United States is exported to Asia where it is considered a delicacy.

Commercial Sources

Pacific geoducks are found in the eastern North Pacific, from Alaska to the Gulf of California in Mexico.

The main sources of Pacific geoducks are the United States and Canada.

Capture Methods

Pacific geoducks come from coastal fisheries and shellfish farms. Wild geoducks are primarily harvested by divers. Farmed geoducks are grown in bottom cultures. They are individually “planted” in the intertidal zone and are harvested by hand.

+-Pacific littleneck (farmed)
Best
Low

MORE ABOUT PACIFIC LITTLENECK

Pacific littlenecks are a species of clam found along the Pacific coast from California to Alaska, commonly in protected bays and estuaries. They can live as long as 10 years and grow up to 3 inches (8 cm) long.

Commercial Sources

Pacific littleneck clams are only harvested in the United States and Canada. The U.S. supply comes predominantly from domestic production.

Capture Methods

Pacific littlenecks come primarily from harvesting wild clams that have settled on farmed manila clam beds.

+-Blood cockle (farmed)
Best
Low

MORE ABOUT BLOOD COCKLE

Cockles are bivalve mollusks that are closely related to clams. They typically grow in marine waters in the inter- and shallow sub-tidal depth range and are distributed across much of the world.

Commercial Sources

Blood cockles are produced in large quantities in China, Thailand, Malaysia and Indonesia. Both Indonesia and Thailand export cockles to the United States. However, available import data does not specify what species of clams or cockles are imported.

Capture Methods

In China, Malaysia and Thailand cockles are predominantly farmed in nearshore shallow waters on bottom, whereas in Indonesia most clams are reportedly from wild harvests.

+-Ocean quahog (wild)
OK
Low

MORE ABOUT OCEAN QUAHOG

Ocean quahogs are found in the Atlantic from Newfoundland to Cape Hatteras. These slow-growing bivalves reside several miles offshore and can live to 100 years or more.

Commercial Sources

Ocean quahogs are found in the North Atlantic Ocean. In Europe, they occur from the Arctic Ocean to the Bay of Biscay off France. In North America, they range from Newfoundland to Cape Hatteras in North Carolina.

The main source of ocean quahogs is the United States.

Capture Methods

Ocean quahogs come from coastal fisheries, not shellfish farms. They are primarily harvested with dredges.

+-Atlantic surfclam (wild)
OK
Low

MORE ABOUT ATLANTIC SURFCLAM

Inhabiting the southern Gulf of St. Lawrence to Cape Hatteras, the Atlantic surfclam is commercially popular in the mid-Atlantic states, where it is also called the beach clam or skimmer clam.

Commercial Sources

Atlantic surfclams are found in the western North Atlantic, from the southern Gulf of St. Lawrence in Canada to Cape Hatteras in North Carolina.

The main source of Atlantic surfclams is the United States.

Capture Methods

Atlantic surfclams come from coastal fisheries, not shellfish farms. They are primarily harvested with hydraulic dredges.

+-Northern quahog
Unrated
Low

MORE ABOUT NORTHERN QUAHOG

The hardshell clams found on the East Coast of the United States are known as quahogs, so named by the Algonquin Indians, who not only ate the meat but also used the shells to make wampum—beads used for barter and for ornamental purposes. Quahogs come in three sizes, ranging from small to large and called, respectively, littlenecks, cherrystones and chowder clams.

Commercial Sources

Northern quahogs are native to the western North Atlantic, from Nova Scotia in Canada to the Gulf of Mexico. They have been introduced into England, France and the West Coast of North America.

The main sources of northern quahogs are the United States and Canada for wild species, and the United States and Taiwan for farmed species.

Capture Methods

Northern quahogs come from coastal fisheries and shellfish farms. Wild quahogs are primarily harvested with rakes and tongs. Additional types of fishing gear include dredges and bottom trawls; they are also handpicked. Farmed quahogs are grown in bottom cultures.

Recommended servings per month

Contaminant Men Women Kids 6-12 Kids 0-5
Ocean quahog (wild) Mercury 4+ 4+ 4+ 4+
Atlantic surfclam (wild) Mercury 4+ 4+ 4+ 4+
Softshell clam Mercury 4+ 4+ 4+ 4+
Butter Clam (farmed) Mercury 4+ 4+ 4+ 4+
Manila clam (farmed) Mercury 4+ 4+ 4+ 4+
Pacific geoduck (farmed) Mercury 4+ 4+ 4+ 4+
Pacific littleneck (farmed) Mercury 4+ 4+ 4+ 4+
Northern quahog Mercury 4+ 4+ 4+ 4+
Blood cockle (farmed) Mercury 4+ 4+ 4+ 4+
Eco details: 
  • Northern quahogs (or hard clams) are the most commonly eaten species of clams in the U.S. and the ones most likely to be found in fish markets and grocery stores.
  • Quahogs go by different names depending on their size (littlenecks, cherrystones, chowder clams).
  • These clams come from wild fisheries and farms, and capturing methods and farming practices generally do little ecological damage.