PACIFIC LITTLENECK CLAM
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
