River connectivity and fish migration considerations in the management of multiple stressors in South Africa

Abstract

People throughout the world depend on the services we derive from freshwater ecosystems. Human land-use activities often affect the quality, quantity and habitat of freshwater ecosystem, which need to be carefully managed to ensure their integrity and provision of services is sustainable. In South Africa, legislation has established resource-directed measures to attain a sustainable balance between the use and protection of water resources. These procedures have been implemented in most of South Africa’s nine water-management areas, resulting in new legislation to protect these resources. Unfortunately, very little protection has been afforded to river connectivity maintenance and fish migrations. For water storage and flow regulation for agriculture and other resource use activities, >610 formal dams and ~1430 gauging weirs have been constructed that act a partial or complete barriers to fish migration on river ecosystems. Only ~60 fish passage structures have been built, but many are not functional. River connectivity and fish migration management appears to be a shortcoming of the existing management approach for multiple stressors.