After the dust has settled

Abstract

Large dams play an important role in addressing energy and water needs, supporting food production, and stimulating economic growth. However, they may also have profoundly negative social and environmental impacts. Large dams significantly transform riverscapes and inherently impact fish populations which directly contribute to the United Nations Sustainable Development Goals (SDGs). With dam building projected to accelerate in developing regions, there is a need to better understand their ecological and social implications for both fisheries development and biodiversity conservation. This thesis investigated these dynamics through a case study of the Lesotho Highlands Water Project (LHWP), a major inter-basin transfer scheme in Lesotho, southern Africa. Using a mixed-methods approach that integrated natural and social science perspectives, the research explored how the LHWP shaped both fisheries development and aquatic biodiversity outcomes in the Lesotho Highlands by examining (1) The emergence and evolution of fishing practices at Katse Dam, a traditionally non-fishing area; (2) The socio-economic implications of foreign fishing tourism development in dam-affected areas; (3) The impacts of inter-basin water transfer schemes on the endangered and endemic Maloti minnow Pseudobarbus quathlambae and community support for their conservation; and (4) The opportunities for fisheries development in Mohale Dam, an invaded aquatic ecosystem. Results revealed complex and often unexpected outcomes. A significant fishery developed organically at Katse Dam despite no historical fishing traditions, challenging assumptions about cultural barriers while demonstrating that unmanaged development creates substantial risks including conflicts with authorities. Foreign fishing tourism at Katse Dam generated economic benefits but revealed inherent inequalities where location-based advantages favoured some communities over others, which was complicated by historical grievances from daminduced displacement. The endangered Maloti minnow experienced a significant reduction in its extent of occurrence, primarily due to habitat loss and predation by invasive species facilitated by inter-basin water transfer tunnel. However, dam-affected communities showed unexpected support for conservation despite worsened living conditions, challenging assumptions about development versus environmental priorities. The study of the invaded Mohale Dam showed that fisheries development was constrained by social dynamics, and how timing of resource exposure and historical grievances significantly influence adaptation trajectories. This thesis demonstrates that the relationship between large dams, fish populations, and fisheries development demands a holistic, context-sensitive approach to assessment and management. The findings advance our understanding of community adaptive capacity in response to large dam development and emphasise the need to: (1) establish governance frameworks before dam construction to prevent unmanaged development; (2) integrate social dimensions into fisheries development and biodiversity planning; (3) recognise that communities can be conservation allies when properly engaged; (4) address historical grievances that undermine trust in development initiatives; and (5) develop adaptive management systems that respond to both ecological and social changes. These insights offer valuable guidance for policymakers and stakeholders involved in large dam projects globally, particularly in developing regions where balancing development needs with environmental and social concerns remains a challenge. Successful outcomes will require moving beyond traditional impact assessments to understand how communities adapt to and derive value from new aquatic resources, while ensuring equitable access and sustainable management for future generations.