Current status of fisheries and fish stocks of the four largest African reservoirs

Kainji, Kariba, Nasser/Nubia and Volta

Edited by
R.C.M. Crul
F.C. Roest

International Agricultural Centre
Wageningen, the Netherlands

Food and Agriculture Organization of the United Nations


The designations employed and the presentation of the material in this publication 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 status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.


The designations employed and the presentation of material in this publication 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 status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

ISBN 92-5-103683-7

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Reservoirs are already important sources of fish in Africa and new reservoirs continue to be built. Monitoring the evolution of reservoir fisheries and the fisheries experiences gained from one reservoir to another provide important information for future reservoir fisheries development and management.

Too often, this information is not readily available because it is not published or otherwise not easily accessible. This publication is intended to help fill that gap by supplying recent accounts of fisheries on four of Africa's largest reservoirs. It follows on from the Status of African Reservoir Fisheries (CIFA Technical Paper, No 10), published in 1984.


FAO Fisheries Department
FAO Regional Fishery Offices
Directors of Fisheries

© FAO 1995

Crul, R.C.M.; Roest, F.C.
Current status of the fisheries and fish stocks of the four largest African reservoirs: Kainji, Kariba, Nasser/Nubia, and Volta.
CIFA Technical Paper, No. 30. Rome, FAO. 1995. 134p.
The post-impoundment bio-ecology of fish fauna, aquatic macrophytes and aquatic birds of Kainji Lake are discussed.
Echinochloa stagnina was the dominant species of the aquatic macrophytes, and was used as livestock fodder during the dry season.
Fish processing, marketing and distribution in the lake basin have improved, while the management and development of the fisheries are still at research and planning levels.
For Kariba, research and fisheries development activities since 1984 are reported. Research focuses on problems related to the pelagic fishery between Zambia and Zimbabwe that lands 30 000 t annually, warranting an effort to manage the fishery efficiently. A joint Zambia/Zimbabwe SADC Fisheries Project is currently operational, and includes a stock assessment group.
Management of the inshore areas is being re-organized through giving resource rights to the fishing communities and hence an incentive to exploit the resource in a sustainable manner.
Basic research, focusing on an increased understanding of the ecosystem, continues. The ecosystem is beginning to stabilize and changes in populations are becoming predictable.
The Aswan High Dam Lake consists of Lake Nasser in Egypt and Lake Nubia in Sudan. Its main purposes since 1964 have been power generation and irrigation.
Seasonal fluctuations of a number of physico-chemical parameters are presented, while phytoplankton composition in 1988 is compared with that in 1976 and 1979. Data on fish biology are given for the main commercial species.
Fish landings decreased from 34 000 t in 1981 to 15 700 t in 1989, but increased again to 21 900 t in 1990 and to 30 800 t in 1991. Tilapias are 89% of total landings. Salted fish production decreased from 57% of the total landings in the early years of impoundment to less than 10% in 1990.
In recent years, the income of fishermen has increased, mainly because of rapidly increasing fish prices.
For Lake Volta, no significant limnological changes have been reported, but an influx of fishermen has led to overexploitation. The main food source of the fish stocks -periphyton attached to submerged trees - is threatened as, during drawdown periods, the trees are increasingly cut to meet increased demand for fuelwood, especially for smoking.
The estimated total yield (36 360 t in 1991) is close to the long-term yield of 40 000 t/year, but fishing effort has increased four-fold in two decades. New fishing techniques, including semi-mechanized purse seining and beach seining, are aggravating the overfishing. Although many of these new methods are prohibited, there is no effective control.
A UNDP/FAO IDAF Project is currently operational.


J.K. Balogun and M.O. Ibeun
Additional information on fish stocks and fisheries of Lake Kainji (Nigeria)

1.    Introduction

2.    Background information on the lake

2.1    The lake environment

2.2    Hydrology

3.    Biological data for the River Niger and Lake Kainji

3.1    Fish species in the Niger and Kainji Lake

3.2    Standing stock of fish

3.3    Morphology and histology of fish species

3.4    Age and growth studies

3.5    Reproductive biology

3.6    Fish parasites

3.7    Productivity and utilization of major emergent aquatic macrophytes

3.8    Aquatic birds

4.    Fisheries

4.1    Fishery yield

4.2    Processing, marketing and distribution of fish

4.2.1    Fish processing research on Lake Kainji

4.3    Fisheries development and management

4.4    Aquaculture

5.    References

Annex: M.O. Ibeun
A preliminary bibliography and analysis of Kainji Lake-related publications, 1961–1991.

C. Machena
Recent developments in the fisheries of Lake Kariba (Zambia/Zimbabwe)




3.1    Phytoplankton

3.2    Periphyton

3.3    Submerged macrophyte communities

3.3.1    Species diversity and biomass

3.3.2    Community structure and zonation

3.3.3    Factors controlling biomass, plant growth form and adaptive strategies


4.1    Factors affecting fish production in Lake Kariba

4.2    Insecticide levels in fish

4.3    Predation on fish

4.4    Changes in fish population

4.5    Stock assessment, population dynamics and yield prediction

4.5.1    Biomass estimations

4.5.2    Population dynamics

4.5.3    Yield prediction

4.6    Multi-species modelling


5.1    Development aspects

5.1.1    The Zambia/Zimbabwe SADC Fisheries Project

5.1.2    Management aspects

5.1.3    Commercial catch statistics

5.1.4    Integrated planning and management of Lake Kariba and its environs

5.2    Socio-economic aspects

5.2.1    Distribution, numbers and ethnic identity of inshore fishermen

5.2.2    Fishing in the household economy

5.2.3    Fishing gear

5.2.4    Processing, marketing and distribution

5.2.5    Constraints


M.M. Rashid
Some additional information on the limnology and fisheries of Lakes Nasser (Egypt) and Nubia (Sudan)

1.    Introduction

2.    The reservoir

2.1    Morphometry

2.2    Water regime and hydrology

2.3    Sediments

3.    Physico-chemical data

3.1    Temperature

3.2    Turbidity

3.3    Electrical conductivity

3.4    Dissolved oxygen

3.5    Inorganic carbon

3.6    Nutrients

3.7    Salinity

4.    Productivity

4.1    Phytoplankton

4.2    Zooplankton

4.3    Benthos

5.    Biology of important fish species

5.1    Age and growth

5.2    Reproduction and spawning

5.3    Food and feeding habits

6.    Fisheries

6.1    Fish landings

6.1.1    Species composition

6.1.2    Seasonality

6.1.3    Catch per unit effort (CPUE)

6.2    Fishing gears

6.2.1    Commercial gears

6.2.2    Experimental gears

6.3    Fisheries economics

7.    Fishery development

8.    References

L.I. Braimah
Recent developments in the fisheries of Volta Lake (Ghana)

1.    Introduction

2.    Limnology

2.1    Water level

2.2    Water chemistry

2.3    Phytoplankton and zooplankton

2.4    Periphyton, aufwuchs and benthos

2.5    Lake productivity

3.    Fisheries

3.1    Fishing effort

3.1.1    Fishing sites, canoes and fishermen

3.1.2    Fishing gears

3.2    Fish production

3.2.1    Commercial catches

3.2.2    Species composition of commercial catches

3.2.3    Species composition of experimental catches

3.2.4    Comparison of commercial and experimental catches

3.2.5    Diversity and ecogroups

3.2.6    Standing crop of fish

3.3    Fish processing and marketing

3.3.1    Production of fuelwood for fish processing

4.    Research and development history

4.1    Applied fishery research activities

4.2    Fishery infrastructure

4.3    Fishery development activities

5.    Other uses of the lake

6.    References


This document contains updates on the fisheries and fish stock situation of the four largest African reservoirs: Kainji, Kariba, Nasser/Nubia, and Volta. These updates summarize new information generated since 1984, when similar such summaries were published by FAO (Kapetsky and Petr (eds) 1984). The four individual papers were written by the authors through FAO's Regular Programme, and subsequently edited by the International Agricultural Centre, Wageningen, the Netherlands.

During the editing process it became apparent that, in the period under consideration, very little stock assessment and fisheries management work had been undertaken in Lakes Kainji, Nasser and Volta. Lake Kariba, in contrast, continued to be well studied, and now benefits from a regional research and management project.

While sufficient data now appear to be available for effective management of Lake Kariba's resources, the present status of the fisheries of Lake Nasser is largely unknown. Data available for Lakes Kainji and Volta appear to indicate a status of overexploitation of the fisheries resources, caused by excessive fishing effort (large numbers of fishermen using nets with too small a mesh).

It is hoped that the publication of these summaries may lead to a renewed interest in the management of the fisheries resources, so that these can be utilized to their full potential and provide maximum quantities of fish to growing riparian populations.

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