Pacific States Marine Fisheries Commission

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DID YOU KNOW? A small juvenile clam can use its foot to crawl to new areas.

SCIENTIFIC NAME: Protothaca staminea.

COMMON NAMES: Tomales Bay cockle, common littleneck, rock cockle, hardshell, rock clam, steamer and butter clams.

DESCRIPTION: Suboval shell with radiating ribs and concentric ridges. The color is highly variable. In the ocean and along the coast, the color is often whitish with patterns of brown lines along the sides. In bays and estuaries, the color is commonly gray or yellowish gray. Pacific littleneck clams are commonly found in the first 2 to 3 inches of substrate, and are found up to 2.5 inches in length.

LIFECYCLE: Spawning in the spring or summer depending on the region, pacific littleneck clam eggs and larvae are dispersed by the current throughout the water column. After developing a foot, larvae move to the bottom and search for a suitable surface to which they can attach. Young clams often attach in deeper water. As the clam grows, it moves toward shallower water. Adults are sedentary.

HABITAT AND ECOLOGY: Adult and juvenile Pacific littleneck clams are found in coarse, sandy-rock muds of estuaries and on the open coast where there is appropriate substrate, detritus (decaying plant material) and protection from predators. This species gathers food by filtering water for phytoplankton and diatoms. Rock crabs, fish, birds, sea otters, and others feed on clams depending on the region.

Because of their sedentary nature, clams are highly susceptible to human-induced changes in their environment. High coliform bacteria levels resulting from municipal sewage discharges have permanently closed some areas to harvest. High siltation caused by logging, upland development, dredging, and marina construction affect the abundance of Pacific littleneck clams. In addition, this species of clam is very sensitive to copper which is used in antifouling boat paint. Coastal wetland destruction also adversely impacts this species since detritus, generated by the decay of wetland plants, is an important food source for the clam.

RANGE: The Pacific littleneck clam is abundant in Pacific coast estuaries from Baja California to the Aleutian Islands in Alaska. Significant spawning grounds include Coos Bay, Tillamook Bay, Yaquina Bay, and Puget Sound, Grays Harbor and Willapa Bay.

ECONOMIC VALUE: An important part of the heritage of many coastal communities and a key factor in rural economies, the Pacific littleneck clam is commercially harvested from Prince William Sound, Alaska, to Southern California. Pacific littleneck clams make up 8% of the entire clam harvest along the Pacific coast and is usually sold fresh in the shell, frozen or canned. Additionally, the Pacific littleneck clam is an important recreational species due to its good taste and accessible habitat.

Revised 12/16/96