About the editor John F. Caddy has been actively involved in fisheries research and its application to managing fisheries since he completed his doctoral research on the ecology of an estuarine shellfish at the University of London twenty years ago. Much of his professional career with the Government of Canada was concerned with the population dynamics of marine invertebrates, and he is the author of numerous scientific papers on this subject. He is currently employed as Senior Fishery Resource Officer in the Food and Agricultural Organization of the United Nations in Rome, and permission from the Organization to undertake this work is gratefully acknowledged. In his present position, he has been able to draw upon his experience in a wide range of national and international fisheries in selected chapters that illustrate the main research approaches currently used in invertebrate fisheries today.