Some simple methods for the assessment of tropical fish stocks
| Some simple methods for the assessment of tropical fish stocks |
by
Daniel Pauly
Associate Scientist
International Center for
Living Aquatic Resources Management
Makati, Metro Manila, the Philippines
First printing 1983
Second printing 1984
The designations employed and the presentationof material in this publication do not imply theexpression of any opinion whatsoever on thepart of the Food and Agriculture Organizationof the United Nations concerning the legalstatus of any country, territory, city or area orof its authorities, or concerning the delimitationof its frontiers or boundaries.
M-43
ISBN 92-5-101333-0
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FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 1984
© FAO
This document is a revised version of FAO Fisheries Circular No. 729, issued inEnglish and French. The present version is also available in Spanish.
| Distribution: | For bibliographic purposes this documentshould be cited as follows: |
| FAO Fisheries Department FAO Regional Fisheries Officers Selector SM Author | Pauly, D., Some simple methods for the1983 assessment of tropical fishstocks.FAO Fish.Tech.Pap., (234):52 p. |
| ABSTRACT |
This selection of methods is based on lecture notes used at a FAO/DANIDA trainingcourse held in Mombasa, Kenya, in May-June 1980. The methods presented are:regression and correlation, estimation of growth parameters from length-frequency data,estimation of mortalities (total, natural, fishing mortality) and analysis of catch andeffort data. |
Only methods that are inherently simple and applicable in the tropics are discussedin detail while more advanced concepts such as the distinction between different formsof overfishing, stock-recruitment relationships, multispecies interactions are introducedin the form of an essay. A brief annotated bibliography of tropical fish stock assessmentis included. |
Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.
The present report provides an introduction to the methods of stock assessment particularlytailored to the needs of fisheries workers concerned with the complex resources ofthe tropical and subtropical areas of the world. In adapting existing methods (largelydeveloped in the temperate and cold temperate regions of the world) for use in the tropics,the author has attempted to illustrate the main principles in as simple and direct way aspossible, drawing upon concrete examples from actual published fishery data.
The text of this paper is taken, largely unchanged, from the notes of the lecturesgiven by the author at the FAO/DANIDA Training Course on “The Methodology of FisheriesScience (Biology)”, held from 19 May to 14 June 1980 in the Kenya Marine Fisheries ResearchInstitute (KMFRI) in Mombasa, specifically aimed at an audience drawn from countries borderingon the Western Indian Ocean. This text is an improved version of FAO Fish. Circ. No. 729.
The course followed the usual FAO format: a brief, stremlined exposition of the mainpoints of the subject-matter was followed by roundtable discussions and worked examples duringwhich the pros and cons of the different methods and pitfalls in their application wereexplained fully. The worked examples used in the course are given in the text of the lecture,and it only remains to point out to the student reader that the application of any method(especially a `short-cut' method) should not ignore the principles underlying the applicationof scientific methods in marine science.
These principles may be briefly summarized by four questions which the worker shouldask himself or herself before and during the course of the analysis:
If all these questions are asked before and during the analysis, then the results of aparticular procedure may be viewed with the appropriate degree of confidence, particularlyif the assumptions underlying each method are understood and borne in mind at all times.
| J. F. Caddy FAO, Rome February 1983 |