The ICES International Symposium on Fisheries and Plankton Acoustics was hosted by the Marine Laboratory, Aberdeen, Scotland, from 12 to 16 June 1995, with 267 registered participants from 34 countries presenting work from all the world’s oceans and continents. It was the fourth in a series of International Symposia organized by ICES on the subject of acoustics, and followed those held in Bergen in 1973 (Rapports et ProcesVerbaux des Reunions, 170) and 1982 (FAO Fisheries Report No. 300; Rapports et Proces-Verbaux des Reunions, 184) and in Seattle in 1987 (Rapports et ProcesVerbaux des Reunions, 189). The Symposium was co-sponsored by the Institute of Acoustics, the Acoustical Society of America, and Societe Francaise d’Acoustique, and benefited from the financial support of a number of organizations, in particular the European Commission Programme AIR, FAO, MLAAberdeen, IMR-Bergen, IFREMER, and ORSTOM. The Symposium was proposed by the ICES Fish Capture Committee; John Simmonds (UK) was appointed Convener and local organizer with Francois Gerlotto (France), D. Van Holliday (USA), David MacLennan (UK), Egil Ona (Norway), and Jim Traynor (USA) forming the Steering Committee. The primary objective of the Symposium was to bring together scientists from around the world, many of whom meet too infrequently. Papers were invited on improvements in techniques, the development of technology and instrumentation, the assessment of current problems, and the identification of future research requirements. The scope was kept as wide as possible as researchers are often aware of developments in their own area of expertise but sometimes less familiar with peripheral but associated activities. Since 1987, technological development and the understanding of statistical treatment have developed considerably and have had implications for the kinds of data that can be collected, experimental designs, and data analysis. The Symposium highlighted the care and sophistication of today’s measurements and the enormous breadth of the application of acoustics for biological studies in the aquatic environment. The range of analytical techniques applied to acoustic data is substantial, from neural networks and discriminant functions for the recognition and identification of targets, matrix manipulation and deconvolution techniques for twoand three-dimensional evaluation and reconstruction, target tracking for behavioural studies, and spatial statistical techniques for mapping and evaluating distributions of populations. The participants benefited greatly from the breadth of activities covered, many of us getting new ideas and directions for future study that would not have been possible without a meeting of this type. ‘‘Fisheries and plankton acoustics: past, present, and future’’ by David MacLennan and D. Van Holliday at the end of this volume is an excellent summary of the Symposium. These proceedings are an important part of the Symposium. Great emphasis has been placed on ensuring that the papers selected have been refereed and edited to a high standard and published quickly, ensuring that the best science is available in the published literature as soon as possible. This issue of the ICES Journal of Marine Science, reflecting the full breadth of scientific content of the Symposium and the current state of understanding, comprises 43 full papers and 18 short communications selected from the 101 verbal and 62 poster presentations, all of which are listed along with authors’ addresses (see list on page 519). The remaining unpublished papers provided a wealth of stimulating ideas which I hope to see developed and published over the next few years. The timely publication of these proceedings owes a lot to the prompt action of all the authors, who made the final revision dates on time, and the referees (listed on page 517), who responded both quickly and comprehensively. Both David MacLennan and I acknowledge the considerable efforts of Dr Chuck Hollingworth, who administered the whole process, and Dr Sandy Mackie and Professor John Blaxter, both of whom made important contributions to the editing.