An Evaluation of the Malawi Catch Assessment Survey of Traditional Fisheries
A report prepared by the GOM/FAO/UNDP Chambo Fisheries Research Project
MALAWI
| An Evaluation of the Malawi Catch Assessment Survey of Traditional Fisheries |
FI:DP/MLW/86/013, Field Document 14, March 1992
by
G.F. Turner, M.B.D. Seisay and N.P. van Zalinge
For bibliographic purposes this document should be cited as follows:
Turner, G.F., M.B.D. Seisay and N.P. van Zalinge. 1992 An evaluation of the Malawi catch assessment survey of traditional fisheries. GOM/UNDP/FAO Chambo Fisheries Research Project, Malawi, FI:DP/MLW/86/013, Field Document 14: 25p.
This report was prepared during the course of the Chambo Fisheries Research project. The conclusions and recommendations given in the report are those considered appropriate at the time of its preparation.
The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or constitutional status of any country or sea area, or concerning the delimination of frontiers.
The catch and effort estimates produced by a gear-based sampling system (MTF) carried out by the project are compared with those of the boat-based Catch Assessment Survey which has been used by the Malawi Fisheries Department since 1976. It is found that MFT provides much more reliable estimates, showing smooth trends in gear activity and catches within the year. Total production estimates for all species caught and all gears used differed little between the systems in areas of high fishing activity. However, CAS effort estimates, and catch per unit effort figures were highly inaccurate, thereby rendering the CAS figures of limited use for stock assessment purposes. Inaccuracies in estimates mean that even dramatic trends may be masked for several years, perhaps until corrective action is too late.
Analysis of past data collected by the CAS reveals a number of sources of error, some of which are the result of the complexity of the recording forms and the large degree of manual calculation involved. Other sources of error were found to be the result of factors intrinsic to the system, such as the methods of choice of beaches and of calculating raising factors. These latter factors cannot be eliminated from the CAS system, and, in addition, no computerised analysis facility is presently available. Since both of these objections have been overcome with the MTF system, it is recommended that the MTF system be implemented on a nationwide basis without delay.
Map showing the project's working area and statistical divisions (minor strata).
FOOD AND AGRICULTURE ORGANISATION OF THE UNITED NATIONS
Monkey Bay, Malawi, March 1992
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An Evaluation of the Malawi Catch Assessment Survey of Traditional Fisheries
3. EVALUATION OF THE PERFORMANCE OF THE CAS, 1976–1991
APPENDIX 1: Gillnet Fishery South of Boadzulu Island 1984–1991