A report prepared by the GOM/FAO/UNDP Chambo Fisheries Research Project

MALAWI

AGE AND GROWTH PARAMETERS OF CHAMBO (OREOCHROMIS SPP.) IN THE SOUTH EAST ARM OF LAKE MALAWI, AS DETERMINED FROM OPERCULAR BONES.

TABLE OF CONTENTS

FI:DP/MLW/86/013, Field document 20, March 1992

Moses Chapomboloka Banda

For bibliographic purposes this document should be cited as follows:

BANDA, M.C. 1992 Age and growth parameters of the chambo (Oreochromis spp.) in the south-east arm of Lake Malawi, as determined from opercular bones. GOM/UNDP/FAO Chambo Fisheries Research Project, Malawi. FI:DP/MLW/86/013, Field Document 20: 31p.

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. They may be modified in the light of further knowledge gained at subsequent stages of the project.

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 Agricultural Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.

Map showing the project's working area and statistical divisions (minor strata).

ACKNOWLEDGEMENTS

The author thanks Mr. N.P. van Zalinge for reading and correcting the manuscript.

I would also like to express my sincere thanks to the technical staff of Monkey-Bay Mr. L. Phiri, Mr. A.L. Bowa and Mrs. L. Mzunzu who were involved in the preparation of opercular bones.

FOOD AGRICULTURAL ORGANISATION OF THE UNITED NATIONS
Monkey-Bay, Malawi, March 1992

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.

This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.

Map of the project area
Acknowledgements
Abstract

1. INTRODUCTION

2. METHOD

2.1 Sample collection
2.2 Preparation of opercular bones for band counting and back-calculation

2.2.1 Length-at-age data
2.2.2 Back-calculation data

2.3 Theoretical growth

2.3.1 Length-at-age and back-calculated length-at-age data
2.3.2 Length-frequency data

2.4 Age-length key

3. RESULTS AND DISCUSSION

3.1 Growth zones
3.2 Age determination
3.3 Theoretical growth curves
3.4 Verification
3.5 Length-age key tables
3.6 Conclusion

4. REFERENCES

LISTS OF FIGURES

Figure	1a:	Relation of fish length and age for Oreochromis lidole
Figure	1b:	Relation of fish length and age for Oreochromis squamipinnis
Figure	1c:	Relation of fish length and age for Oreochromis karongae
Figure	2a:	von Bertalanffy growth curves for chambo species. Linf and K by Walford plot from length-at-age data.
Figure	2b:	von Bertalanffy growth curves for chambo species. Linf and K by Gulland plot from length-at-age data
Figure	2c:	von Bertalanffy growth curves for chambo species. Linf and K by Munro plot from length-at-age data
Figure	3a:	von Bertalanffy growth curves for chambo species. Linf and K Walford plot from back-calculated data
Figure	3b:	von Bertalanffy growth curves for chambo species. Linf and K by Gulland plot from back-calculated data
Figure	3c:	von Bertalanffy growth curves for chambo species. Linf and K by Munro plot from back-calculated data
Figure	4:	von Bertalanffy growth curves for chambo species. Linf and K by Least Square Non-linear Regression method from length-frequency data
Figure	5:	The growth curves of Tilapia saka (O. karongae) and Tilapia squamipinnis (O. squamipinnis) by various methods (after Lowe)
Figure	6:	A comparison of growth curves for chambo species. (Banda = B and Lowe = L)
Figure	7a:	The general growth curve pattern for O. lidole. TTML = theoretical total mean length by the growth curve model
Figure	7b:	The general growth curve pattern for O. squamipinnis. TTML = theoretical total mean length by the growth curve model
Figure	7c:	The general growth curve pattern for O. karongae. TTML = theoretical total mean length by the growth curve model

Lists of tables

Table	1:	Analysis of covariance (ANCOVA) of length-at-age by species (P>0.05)
Table	2:	Chambo spp. Mean lengths with the corresponding standard deviation and confidence limits, annual growth increment and numbers at each group
Table	3:	The back-calculated total mean lengths (cm) of Oreochromis species at each age group
Table	4:	Chambo spp. Mean length at age group (after Lowe 1952)
Table	5:	Estimates of the average instantaneous growth rates in length and weight
Table	6:	Analysis of variance of data from Table 2
Table	7:	Analysis of variance of data from Tables 2 and 4
Table	8:	Estimated von Bertalanffy growth parameters and growth performance
Table	9:	Mean lengths of components dissected from Bhattacharya analysis (Seisay, 1992)
Table	10:	Estimated growth parameters and growth performance indices using length-frequency data (Seisay, 1992)
Table	11:	Estimated growth parameters and growth performance indices according to Lowe's (1952) data and Moreau (et al, 1986) report
Table	12:	Length-frequency of chambo in each age group
Table	13:	Age-length keys for a commercial fishery of Oreochromis species (Proportion of chambo in each age group)

ABSTRACT

Annual banding on opercular bones were used to age chambo, O. lidole (N= 137), O. squamipinnis (N= 190) and O. karongae (N= 206), sampled from commercial catches in the south east arm of L. Malawi in 1990 and 1991. The annual banding was verified by comparing my results to those obtained by an independent study on length-frequency data.

The oldest fish was aged 6+ for all three species. Mean back-calculated total lengths (TL) for O. lidole, O. squamipinnis and O. karongae aged 1–6 were 14.0, 18.84, 22.9, 26.0, 28.53 and 31.05, 13.75, 19.24, 23.01, 26.15, 28.36 and 30.5, 13.83, 18.98, 22.12, 25.20, 27.82 and 30.2cm TL, respectively. The von Bertalanffy growth equations for O. lidole, O. squamipinnis and O. karongae were

Lt = 43.2(1-exp(-0.18(t+1.29)))

Lt = 37.7(1-exp(-0.24(t+0.97)))

and

Lt = 41.3(1-exp(-0.18(t+1.34)))

respectively. These results indicate that chambo species have similar growth pattern.