Experiments with the American Hard-Shelled Clam (Mercenaria mercenaria) 1969

Abstract

The American hard-shelled clam (Mercenaria mercenaria) is a valuable bivalve molluscan shellfish in the U.S.A, and Canada. This bivalve is somewhat like the cockle (familiar to most Irish people) or the palourde (Venerupis decussata) which is gathered on some parts of the Irish coast and exported to France. Unlike the cockle which lives in sand, or the palourde which is found mainly in coarse sand and shingle, the hard-shelled clam lives in sandy mud. Some years ago this clam established itself in Southampton Water, on the south coast of England. It is thought that this particular stock originated from live clams thrown overboard from an American liner. Due to the warming effect of the outflow from a large power station near Southampton, coupled with naturally occurring high sea-water temperatures in this area, the clams were able to breed and multiply. Normally the seawater temperatures around the coasts of Gt. Britain and Ireland are too low to permit the clams to multiply by natural breeding.