I would like to thank the Fisheries Department of the Food and Agriculture Organization of the United Nations who suggested that I should prepare this manual while I was a consultant and, through the UNDP/FAO Aquaculture Development and Coordination Programme (ADCP), who financed its publication.
My personal thanks are extended to those FAO Fisheries Department staff members with whom I have discussed the purpose of this manual, especially André Coche, Mario Pedini and Michel Vincke. Manuela d'Antoni is also complimented on the drawings which she patiently prepared for this manual.
Thanks are also due to the many authors whose works are cited here and to Dr. U.P. Grunder of Buhler Brother Ltd., who provided cost information and some of the photographs.
Finally I wish to thank my wife Janet and my daughter Sophie for their encouragement and help in the task of preparing this manual and the secretaries who have worked on its various stages of preparation -Mairi Page and Sandra Castrucci.