Lake Malawi: fishes, fisheries, biodiversity, health and habitat

Abstract

Lake Malawi's fishes are a source of food for millions and provide a livelihood for thousands by encouraging tourism, fascinating the scientific fraternity, enchanting aquarists around the world and maintaining ecosystem processes in the lake. From a fisheries and resource assessment perspective, the region is data-poor, but there is sufficient peer-reviewed and grey literature on the limnology, fisheries and ichthyofauna of the lake to provide a good overview of the state of the fishery. There are signs of over exploitation and an increasing fishing effort has resulted in decreased catch rates, depletion of larger, more valuable species in the fishery and species changes. The fishery is harvesting stocks that were formerly thought to be under exploited. Previous attempts to manage the fishery have been ineffective and long term strategies addressing overfishing will need to transform the fishery from an open-access to a limited access system. As important as direct intervention in the management of the fisheries, will be the management of catchment processes. Increased nutrient inputs; changes to the phytoplankton composition; sediment loading; nearshore water quality impacts and changing water levels threaten the ecosystem. Introduction of alien invasive organisms is an ever present threat to the ecosystem as well, due to continued development of small scale aquaculture in the region. The overriding causative factor for all these effects is the poverty of the lakeshore communities which do not have the economic privilege of being able to adapt their utilisation patterns.

Keywords:

• overfishing
• limnology
• yield
• cpue
• Nyasa
• Niassa

Acknowledgements

The authors would like to thank the conveners Frits Roest, Martin van der Knaap and Mohiuddin Munawar and the Aquatic Ecosystem Health and Management Society for inviting this paper, Jose Halafo for providing current effort estimates for Mozambique, and Anthea Ribbink for her careful editing of this manuscript. Two anonymous referees are thanked for their valuable comments on the manuscript.