Browsing by Author "Khoa, Sophie Nguyen"

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Assessment and Management of Irrigation Impacts on Tropical Inland Fisheries: A Case Study from Sri Lanka
(2003) Khoa, Sophie Nguyen; Smith, Laurence; Lorenzen, Kai; Garaway, Caroline; Perera, L. R.; de Silva, Shyamalie; Kumara, M. M .C.; Amarasinghe, Upali A.; Kularatne, M. G.; Bandara, H. M. S. Chandana
"Inland fisheries make an important contribution to rural livelihoods in many developing countries. Water resources development for irrigated agriculture often has significant and complex impacts on inland fisheries, either negative or positive. The assessment and management of such impacts is important in order to minimize undesirable outcomes of irrigation development in terms of livelihoods and/or aquatic biodiversity. This paper outlines the application of a holistic and participatory approach to fisheries impact assessment of the Kirindi Oya irrigation scheme in Sri Lanka. The overall impact of irrigation development on fisheries production in the watershed has been assessed as moderately positive, with production from reservoir fisheries outweighing the estimated loss of production from river-floodplain fisheries. Stakeholders identified increased drawdown in reservoirs due to very high irrigation demand, and drainage water inflow into coastal lagoons as the main physical impacts of irrigation development on fisheries. These impacts led to conflicts between farmers and fishers regarding water management in the reservoirs and lagoons. Underlying these impacts and conflicts are weak linkages between irrigation and fisheries institutions. Stakeholders identified rehabilitation of irrigation infrastructure and increased water productivity in agriculture as key measures to reduce both, draw down of reservoirs and drainage flows into the lagoons. Improvement of institutional arrangements for water management is crucial to resolving conflicts and ensuring an equitable allocation of water between agriculture and fisheries."
Impacts of Irrigation Development on Capture Fisheries in the Rice-Based Farming Systems of Southern Laos
(2003) Khoa, Sophie Nguyen; Lorenzen, Kai; Garaway, Caroline
"Fish populations inhabiting the rivers, streams, natural wetlands and paddy fields of rice-based farming systems support capture fisheries of major importance to local livelihoods. Water resources development for irrigation has the potential to impact significantly on these fisheries by modifying habitats and their connectivity, as well as patterns of exploitation. We conducted a field survey to establish the impacts of small to medium sized weir and dam irrigation schemes on local fisheries in the rice-based farming systems of southern Laos. The survey was replicated at the irrigation scheme level. Impacted sites were paired with non-impacted controls within the same watershed. Weir schemes were associated with a significant decline in households and per-area catches which as not fully explained by a concomitant change in fishing effort. Dam schemes caused no significant overall decline in catches, but a very significant re-distribution of catches and effort into the newly created reservoirs. In both weir and dam schemes, changes catch were largely explained by changes in fishing effort. No significant impacts on fish species richness were detected. Small-to-medium sized irrigation schemes have only moderate impacts on local fisheries in rice-based farming systems. Net impacts of weirs may be more pronounced than impacts of dams. Rather than being fundamentally degraded as often assumed, fish populations and the fisheries they support can remain productive and diverse within irrigated rice systems. Protecting and enhancing wild fish stocks in such systems is likely to generate social and ecological benefits."