The growth ofMytilus edulisL. (Bivalvia) from Disko and Thule district, Greenland

Abstract

The growth in length of Mytilus edulis L. from Disko and the Tliule district is estimated by means of the very distinct winter growth checks. The growth is highly sigmoid and can be described by a combination of the Gomperz equation (valid for the growth until about half the ultimate length is attained) and the von Bertalanffy equation (valid for the growth from about one third of the ultimate length) as neither of the two growth equations covers the whole size range of Mytilus. The growth of the species at Greenland is slow compared with its growth in most temperate areas. Doubtlessly low temperature is the cause of the slow growth. When the growth rate is related to day-degrees, growth at Greenland almost equals that found in similar habitats in temperate regions. An apparent size-dependent mortality occurs among the very small Mytilus living on Fucus. However, this phenomenon is probably caused by differential emigration among the small individuals. A conspicuous lack of young individuals in the samples from the Thule district indicates that practically no settling took place after 1959 in that area.