Northern Quahog
(Mercenaria mercenaria)

Description: The exterior of the thick oval-shaped shell bears strong concentric rings. These rings are evenly spaced except for on the ends of the shell where they progressively crowd together. The lunule formed between the two shells makes a heart shape. This long-lived species can attain a length of 15 cm, though typical individuals are smaller. The external color varies from gray to fawn, while the inside of the shell is yellowish-white, usually with a purple spot near the hind end.

Habitat: This species burrows into sandy substrates or muddy bottoms of sheltered waters and ranges from the intertidal zone to a depth of 10 m. Northern quahogs can withstand a wide range of salinity conditions.

Origin: East Coast of North America.

Invaded Areas: Populations have become established in two or three west coast estuaries, including in Southern California (Colorado Lagoon) and British Columbia (Boundary Bay).

Concerns: The Northern Quahog can be readily purchased, alive, at local seafood stores. These clams originated on the East Coast, where they are the basis of a lucrative commercial fishery. They have been intentionally introduced to numerous areas outside their native range in the hopes of establishing a fishery, but can only reproduce when temperatures reach about 27°C, conditions that are only met in very shallow estuarine lagoons on this coast. Northern quahogs could outcompete native suspension feeders in such habitats.