Browsing by Author "Lorenzen, Kai"

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Adaptive, Participatory and Integrated Assessment (APIA) of the Impacts of Irrigation on Fisheries, Evaluation of the Approach in Sri Lanka
(2004) Nguyen-Khoa, Sophie; Smith, Laurence; Lorenzen, Kai
"Irrigated agriculture is the largest user of water globally and its development can have significant impacts on inland fisheries. These impacts can be varied and complex, and range from biodiversity concerns to economic impacts and changes in the livelihood opportunities of rural households. There is a need to improve the knowledge of these impacts and integrate their assessment into project planning and implementation. This paper describes an approach designed to meet this challenge and the results of its pilot-testing in Sri Lanka. The approach derives from a literature review of planning and appraisal methodologies, interaction by a multidisciplinary team of researchers and evaluation of the test case."
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."
Impacts of Irrigation on Inland Fisheries: Appraisals in Laos and Sri Lanka
(2005) Nguyen-Khoa, Sophie; Smith, Laurence; Lorenzen, Kai
"There is an increasing recognition of the need for improved approaches for integrated water resources management (IWRM). In many river basins irrigation is the largest water use, and attention must be paid to its socioeconomic and environmental impacts, and to the potential for multiple-use of irrigation systems. This requires improved approaches for the planning, impact assessment and management of irrigation projects, and an important component, the assessment and management of impacts on inland fisheries."
Management and Livelihood: Interrelation between Fishing and Other Activities in Managed Communities in the Amazon Floodplain
(2004) Almeida, Oriana T.; Lorenzen, Kai
"Previous research on the subsistence oriented fisher in the Amazon had suggested that fishing, agriculture, and ranching are closely related to each other. When communities in this region undergo under management the productivity of the fishing activity is increased and research has showed that extra time is saved to practice other activities. The objective of this work is to understand the relation between fishing and other activities in fishing communities in the Lower Amazon. By using a survey conducted in 18 paired communities with and without co-management agreements (i.e. 9 pairs of a co-managed and non-managed fishery each) this study had the objective to evaluate the changes in household practices once management is installed in a community and fish productivity increases. A total of 259 households were surveyed to estimate total income of economic activities, fishing effort, and catch. Results showed that the increase in productivity in managed lakes is actually the result of exclusion of external fishers and not the result of reduction in household time expended in fishing activity. This unchanged relation between fishing time in communities with and without management is also true for other activities as there is no significant difference between agriculture and cattle ranching practiced between managed and unmanaged communities (average crop area and heard size per family). A linear regression of fishing income and income of other activities and social variables showed a light significant positive relation between fishing (using canoe) and agriculture and a negative relation with retirement income but did not show any relation with cattle, number of fishing boats, and income from salary. Using this analysis no relation was established between ranching and fishing activity giving evidence that fishing is not associated or subsidizing deforestation for cattle ranching."