Managing reservoir fisheries: a critical look at reservoir physical environment

Abstract

Reservoirs are rarely constructed solely for fishing. However, as a secondary purpose, fisheries augment the benefits derived from these artificial systems. The factors discussed in the ensuing four paragraphs should be considered in creating an "optimal" reservoir for fishing.First, the desired fishery should be developed from an ecosystem perspective-including the introduction of commercial species that are adequate in terms of fish production characteristics and ecosystem demands. According to (Cowan Jr et al 2012), the ecosystem approach to fishery has been promoted as one way forward for sustainable management of fisheries resources since it more holistically addresses complex links across human and natural systems, finds conflicts between Abstract This short note follows a discussion on a study that assessed reservoir fisheries and ecosystem-based management approaches in Ghana. The main objectives of the study were to develop an understanding of how differences in reservoir morphometry and physicochemical characteristics influence ecosystem structures and fisheries productivity. This involved reviewing and updating empirical models for reservoir harvest estimations, relating morphometric characteristics of the reservoirs to fish production, assessing the exploitation levels and stock status of the reservoirs' target species and providing a holistic description of the reservoirs' biological interactions through a food web modelling approach. To manage reservoirs and associated riverine environments for the benefit of fish and fisheries, reservoirs' status and contribution to capture fisheries production have to be evaluated and addressed. Furthermore, the technical criteria and measures germane to assessment frameworks must be improved. Protecting and enhancing the physical environment of reservoirs for fish production requires considerations of ecosystem perspectives, optimal morphometric characteristics, duration of reservoir filling and development and prevention of critical nutrient enrichment. For enhancing Ghana's fish production, development strategies should focus on fisheries and aquaculture production in rivers, floodplains, lakes, reservoirs, and brackish water systems. Research, policy, and capacity-building issues related to developing these production systems must be addressed adequately. Moreover, to fully exploit their potential, the management requirements of the individual reservoir systems need to be assessed and appropriate regimes implemented with stakeholders.