Strange Spatfall of the Common Mussel on the Common Cockle

Abstract

AN interesting and unusual spatfall of the common mussel, Mytilus edulis, on the common cockle, Cardium edule, resulting in a related and dual mortality was observed in 1932 in the course of investigations on the extensive cockle beds of Cark sands at the head of Morecambe Bay. In June, heavy falls of mussel spat (5–10 mm. long) were found in several large areas on these beds, an event unprecedented in the experience of local middle-aged fishermen. At low water on these desert-like sands, the areas with mussels loomed in the distance like rocky outcrops. Such an unusual spatfall may be regarded as a natural experiment on the part of Mytilus to establish itself on sandy ground.