A comparison of the age, growth rate and burrowing behaviour of the razor clams, <i>Ensis siliqua</i> and <i>E. ensis</i>

Abstract

Two razor clam populations from two shores in North Wales were identified on morphological grounds as Ensis siliqua (L.) and E. ensis (L.). Ensis siliqua occurs in fine sand on the exposed south-westerly facing shore of Newborough beach, whilst E. ensis inhabits the coarser sediment of Penmon beach, a sheltered north-easterly facing shore in the Menai Strait. At Penmon smaller E. ensis (&lt;100 mm) inhabited sediments at mean low water of spring fides, whereas larger individuals (&gt;100 mm) occurred almost subtidally at extreme low water springs. No small E. siliqua (&lt;110 mm) were found on Newborough beach, where there has been a noticeable decline between 1990 and 1992 in the number of individuals larger than 175 mm. Growth of the two species was different. The von Bertalanffy growth constant, k , was similar in the two species, but E. siliqua had a larger asymptotic length than E. ensis .