Management of the introduction and transfer of marine molluscs

1. The introduction and transfer of marine molluscs for fisheries and aquaculture will include a risk of transporting competitors, predators, parasites, pests and diseases which can compromise intended molluscan culture and wild fisheries. 2. Introductions as well as transfers, in the course of normal trade, particularly of half-grown oysters, have been responsible for the establishment of several harmful and nuisance non-native species. Once established at a new locality these may continue to be moved by various means or by natural expansions of their range. 3. Several taxa have been associated with molluscan introductions and range expansions of these can be rapid should more than one dispersal vector be involved. 4. A Code of Practice for the introduction and transfer of marine organisms, prepared by the International Council for the Exploration of the Sea, provides a procedure which enables responsible movement of commercial species. In the case of an introduction it requires examination of the intended species by assessment of its likely ecological and genetic interaction with native species in advance of its release. It also includes measures, which if adopted, considerably reduce the risk of introducing accompanied unwanted species. 5. Introduced and useful species themselves, intended for culture, have seldom caused subsequent difficulties. 6. In this account the management of movements of non-native species, to and within northern Europe, are discussed. ©1996 by John Wiley & Sons, Ltd.