The Cape Critical Rivers (CCR) Project is a ground-breaking initiative that aims to bridge biodiversity conservation with water resource management in the Olifants-Doring catchment, spanning the Succulent Karoo biodiversity hotspot.
Supported by the Save Our Species (SOS) Foundation, the Endangered Wildlife Trust (EWT) is working with project partners, CapeNature, the Northern Cape Department of Environment and Nature Conservation (DENC) and the Freshwater Research Centre (FRC) towards protecting threatened freshwater ecosystems and species in this critical catchment.
The Olifants-Doring catchment is the heart of the South African fruit farming industry, and of significant conservation importance as the freshwater systems provide habitat for a remarkable 43 species of fish (approximately 10% of Southern African freshwater fish), of which ten are endemic. Unfortunately, eight of these endemic species are listed as Threatened, primarily due to the spread of invasive alien fish species, which is exacerbated by habitat loss due to the increasing demand for agricultural and domestic water use, and pollution.
Most pertinent for the conservation of indigenous fish is the presence of predatory small- and large-mouth bass (Micropterusdolomieuand salmoides), rainbow trout (Oncorhynchusmykiss) and bluegill sunfish (Lepomismacrochirus). Where populations of these alien species successfully establish themselves, it is largely impossible for viable populations of indigenous species to persist, as they are prodigiously preyed upon and outcompeted for food resources. Common carp (Cyprinuscarpio) have also proven to be extremely effective colonizers in this catchment, and although not predatory, they compound the detrimental impacts on indigenous populations by destroying critical spawning and feeding habitats via their bottom-feeding behaviour which increases water turbidity. Remnant populations of indigenous species are therefore primarily restricted to isolated tributaries absent of alien fish. Addressing the issue of invasive alien species and catchment land and water management is therefore critical if we are to conserve these pockets of unique biodiversity and the ecosystems which they inhabit.
The primary objective of the CCR project is to support the implementation of the Biodiversity Management Plan (BMP) for the Endangered Clanwilliam sandfish (Labeo seeberi). One of the gaps identified during public consultations was that there are insufficient resources among the local authorities to implement this BMP. This project aims to fill that gap and capacitate the authorities to protect the critical rivers and the endangered species they support.
Once invasive alien species have established themselves in a system, they are very difficult to remove. Therefore the aim is to preserve the existing critically important pockets of pristine habitat for indigenous fish by working closely with landowners and recreational users in identified high priority indigenous fish sanctuaries to raise awareness of the risks associated with the introduction of alien species to these systems and develop co-operative agreements to prevent introductions in the future. Furthermore, project partners will be working closely with local conservation authorities and researchers to identify viable habitat sites for developing new fish sanctuaries, which might necessitate alien fish clearing and subsequent translocation of the Clanwilliam sandfish, which will be undertaken with adherence to the International Union for Conservation of Nature) IUCN translocation guidelines and with expert facilitation of these processes. The long term objective is to thereby expand the current distribution range and population numbers of this iconic, once abundant species within the bounds of its historic range and create suitable habitat for the natural re-colonization of other indigenous species.
The requirement for intensive irrigation agriculture in this catchment provides a challenging backdrop for the implementation of conservation actions. To promote the sustainable utilization of our freshwater resources, the South African Department of Water Affairs is currently in the final stages of developing the Water Resource Classification System (WRCS), which aims to determine the environmental flow requirements, referred to as the ecological reserve, necessary to sustain ecosystem function in a river. The Olifants-Doring catchment has been the case study for the development of the WRCS, and this project aims to investigate the feasibility and monitor the compliance of implementing the ecological reserve in selected high conservation priority rivers, in collaboration with the Department of Water Affairs. The project partners are engaging with water users (both agricultural and municipal) on sustainable water and land management practices to encourage the sustainable and profitable utilization of our natural resources whilst maintaining the ecosystems which support this unique assemblage of freshwater biodiversity.