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The Committee for Eastern Central Atlantic Fisheries (CECAF) during its 6th Session in Agadir, 11-14 December 1979, stressed the necessity of intensifying the work leading to the assessment of the resources of the region by using acoustic and trawling surveys, and to accelerate the training of national expertise.

The optimization and standardization of the survey methods and techniques to be utilized by all the laboratories are necessary to assure, on the one hand, the rational utilization of available funds and, on the other hand, the comparability of the results between one region and another between one year and another.

The present seminar was a follow-up of the previous two seminars on the same subject (Acoustic methods for fish detection and abundance estimation, TF/RAF/106(NOR), June-July 1978, Casablanca, also Joint ICAAT/ICSEAF/CECAF course on statistics and sampling, April-May 1978, Tenerife) and offered a deeper knowledge and application to the very important question of surveys, both by demersal trawling and by the utilization of acoustic techniques. These questions are presently even more important because a new phase is starting whereby all the laboratories in the region will carry out this kind of research.

This manual has been based, to a large extent, on discussions and experiences covering the acoustic part (Part 2) of the Seminar on acoustic and trawling surveys held 2-14 June 1980, at Casablanca. It touches on all the theoretical and practical statistical aspects of large-scale acoustic surveys of small pelagic fish: sampling design, survey operations, bias and de-bias techniques, and the processing, analysis and critical analysis of the results of the surveys (sonar, echo-sounder). The precise objective was to enable the participants to utilize such knowledge in order to solve their particular problems in their own countries and integrate their activities on a regional basis.

Contributions to the manual have been made by the lecturers, G. Bazigos, J. Burczynski, M. Lamboef, A. Laurec, L. Rijavec and R. Coppola.

We acknowledge our indebtedness to the Director of the Institut Scientifique des Pêches Maritimes, Casablanca and to the Project Manager and staff of the supporting Project MOR/78/018 - Estimation and continued monitoring of marine resources - for their generous contribution in raw material, equipment (sonar, echo-integrator) and processing facilities (mini-computer) which helped to a great extent to make the seminar successful. Additional basic assistance was provided through the Inter-regional Fisheries Development and Management Programme (INT/79/019) particularly from CECAF’s field project based in Dakar, Senegal.

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