I wish to express my sincere thanks to the many who contributed to the preparation of this document; either directly as contributors to various report sections, as reviewers of the drafts, or as supporters of the philosophy and need for this document. Following are the names (in alphabetic order) of those persons who made a contribution under any one of the above headings: V.J. Bye, B. Dybern, E. Egidius, H. Grizel, C. Murarity, A.L.S. Munro, G. Naevdal, H. Rosenthal, C.J. Sindermann (Chairman, ICES Working Group on Introductions and Transfers of Marine Organisms), D. Solomon, K. Tiews (Chairman EIFAC Working Party on Introductions) and R. Welcomme. In addition, I want to thank all other members of the ICES Working Party and EIFAC Working Group who provided comments on the drafts in writing or verbally at our joint WP/WG meetings in 1985 and 1987. Finally, I would like to thank K.E. Smith, Department of Fisheries and Oceans, Halifax, for his detailed review of the text and his advice on structuring the report and N.E. MacEachern and J.E. Stewart, senior regional Department of Fisheries and Oceans staff in Halifax who recognized the importance of this document and allowed me to fit this task into my normal activities.