The Hard Clam (Mercenaria mercenaria), also known as the quahog, is a bivalve mollusk native to the eastern shores of North America, from Prince Edward Island to the Yucatan Peninsula. Older sources may give it the systematic name Venus mercenaria. It is one of many unrelated bivalves referred to as clams. Hard clams are quite common throughout New England, north into Canada, and all down the Eastern seaboard of the United States to Florida, but are particularly abundant between Cape Cod and New Jersey, where seeding and harvesting them is an important commercial form of aquaculture.
In coastal areas of New England, restaurants known as raw bars specialize in serving littlenecks and topnecks raw on an opened half-shell, usually with a cocktail sauce with horseradish, and often with lemon. Sometimes, littlenecks are steamed and dipped in butter, though not as commonly as their soft-shelled clam cousin, the “steamer.” Littlenecks are often found in-the-shell in sauces, soups, stews, “clams casino” or substituted for European varieties such as the cockle in southern European seafood dishes. The largest clams, quahogs or chowders and cherrystones (with the toughest meat), are used in such dishes as clam chowder and stuffed clams or are minced and mixed into dishes that use the smaller, more tender clams.
The term “red tide” refers to an accumulation of a toxin produced by marine algae. Filter-feeding shellfish are affected. The toxin affects the human central nervous system. Eating contaminated shellfish, raw or cooked, can be fatal. Some algal blooms make the seawater appear red, but red tide blooms do not always discolor the water nor are they related to tides. Clams bought from a market should always be safe as commercial harvesters are extremely careful about red tides. They close beds that are even remotely threatened and keep them closed for up to three or four weeks after they are clean of any red tide. Any commercial clam fisher who breaks these rules is in line for a major fine in the first instance and will most likely have their license to harvest or sell clams revoked; furthermore they are liable for any damages.
The quahog is the official shellfish of the state of Rhode Island List of U.S. state shells. The species has also been introduced and is farmed on the Pacific coast of North America and in Great Britain and continental Europe. It reproduces sexually.