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Fingerponds: Seasonal Integrated Aquaculture in East African Freshwater Wetlands

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Fingerponds: Seasonal Integrated Aquaculture in East African Freshwater Wetlands FINGERPONDS: SEASONAL INTEGRATED AQUACULTURE IN EAST AFRICAN FRESHWATER WETLANDS Exploring their potential for wise use strategies Promoter Prof. dr. P. Denny Professor of Aquatic Ecology UNESCO-IHE/Wageningen University, The Netherlands Co-promoter Dr. A.A. van Dam Senior Lecturer in Ecological and Environmental Modelling UNESCO-IHE, The Netherlands Awarding Committee Prof. dr. F. Kansiime Makerere University, Uganda Prof. dr. B. Moss University of Liverpool, United Kingdom Prof. dr. ir. A.J. van der Zijpp Wageningen University, The Netherlands Prof. dr. P. van der Zaag UNESCO-IHE, The Netherlands Fingerponds: seasonal integrated aquaculture in East African freshwater wetlands Exploring their potential for wise use strategies DISSERTATION Submitted in fulfilment of the requirements of the Academic Board of Wageningen University and the Academic Board of the UNESCO-IHE Institute for Water Education for the Degree of DOCTOR to be defended in public on Wednesday, 20 December 2006 at 13:30 hours in Delft, The Netherlands by JULIUS KIPKEMBOI born in Uasin Gishu, Kenya Taylor & Francis is an imprint of the Taylor & Francis Group, an informa business © 2006, Julius Kipkemboi All rights reserved. No part of this publication or the information contained herein may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without written prior permission from the publishers. Although all care is taken to ensure integrity and the quality of this publication and the information herein, no responsibility is assumed by the publishers nor the author for any damage to the property or persons as a result of operation or use of this publication and/or the information contained herein. Published by: Taylor & Francis/Balkema PO Box 447, 2300 AK Leiden, The Netherlands e-mail: [email protected] www.balkema.nl, www.taylorandfrancis.co.uk, www.crcpress.com ISBN10 0-415-41696-5 (Taylor & Francis Group) ISBN13 978-0-415-41696-2 (Taylor & Francis Group) ISBN 90-8504-497-9 (Wageningen University) Table of Contents Abstract vii Chapter 1 General introduction 1 Chapter 2 Biophysical suitability of smallholder integrated 17 aquaculture-agriculture systems (Fingerponds) in East Africa’s Lake Victoria freshwater wetlands Chapter 3 Effects of soil characteristics and hydrology on the 29 functioning of smallholderwetland aquaculture- agriculture systems (Fingerponds) at the shores of Lake Victoria, Kenya Chapter 4 The effects of livestock manure on nutrient dynamics, 49 water quality and fish yields in seasonal wetland fish ponds (Fingerponds) at the edge of Lake Victoria, Kenya Chapter 5 A quantitative assessment of nutrient flows in an 73 integrated agriculture-aquaculture farming system at the shores of Lake Victoria, Kenya Chapter 6 Integration of smallholder wetland aquaculture- 95 agriculture systems (Fingerponds) into riparian farming systems at the shores of Lake Victoria, Kenya: socio- economics and livelihoods Chapter 7 Smallholder integrated aquaculture (Fingerponds) in the 119 wetlands of Lake Victoria, Kenya: assessing the environmental impacts with the aid of Bayesian networks Chapter 8 Synthesis and conclusion 145 Summary 159 Samenvatting 162 Acknowledgements 165 Curriculum Vitae 167 Abstract Natural wetlands around Lake Victoria are threatened by unsustainable exploitation. Poverty and unreliable terrestrial production have led to increased dependence on natural wetlands for livelihoods. The main objectives of this study were to (1) explore the potential of enhancing food production from natural wetlands through a simple and appropriate technology; and (2) investigate the integration of this technology into sustainable floodplain and littoral wetlands farming systems. Fishponds were dug in the wetlands and the excavated soils were used to create raised bed gardens beside the ponds. The ponds were supplied with water and fish stocks naturally by the annual wetland floods. Water balance studies determined the effects of seasonal hydrological patterns on the functioning of the ponds. A trophic model was constructed using Ecopath to evaluate the agroecosystem performance in terms of nutrient flows. The importance of household activities (including Fingerponds) was determined using the sustainable livelihood approach (SLA). Economic analysis determined the performance of fingerponds vis à vis other farming system activities. Annual floods provided adequate stocks of fish (≥3 fish/m2). Water supply depended on natural processes and in a good year the functional period of the ponds is about 5–6 months. A Fingerpond of about 200 m2 provided an additional per capita fish supply of 3.4 kg to a household of 7 people. The potential protein supply is about 200 kg/ha, higher than most other farming activities. This can be increased if pond management is further improved. The wetlands support biomass production activities that are nutritionally and financially important to the households. Trophic and economic assessments revealed that Fingerponds promoted nutrient recycling, enhanced food security and increased the gross margin of an average household by 11%. With discounted fixed costs, the return to household labour per person day was 12.49 euros/ha. There was no evidence of negative impacts on the wetland environment in terms of eutrophication of groundwater. Wetlands resources dominate the livelihood assets of many riparian households. To prevent further encroachment upon them, the productivity of farming needs to be increased to add value to the existing biomass harvesting. Fingerponds contribute to this through their high protein supply per hectare and increased overall yields. This has a potential significance particularly in a region beset by poverty, hunger and malnutrition. The dependence on natural wetland processes (flooding, fish stocking) makes them economically attractive but present uncertainty and high spatio- temporal variability. The investment needed for pond construction may limit adoption by poor households. Institutional support, particularly from the government, NGOs and other local community support groups is required. Further development requires institutional collaboration through multi-stakeholder partnerships; participatory research on integration into existing farming systems, up- scaling and technology improvement; and translation of research results into wetland policies with clear guidelines for communities and decision-makers. vii Chapter 1 General introduction Introduction This thesis investigates the potential of integrating aquaculture ponds (Fingerponds) into smallholder riparian farming systems at the shores of Lake Victoria, Kenya. The overall aim is to contribute to a strategy for the wise use of the wetlands, i.e., to enhance the existing wetland fishery and seasonal agriculture without compromising ecosystem integrity (Davis, 1993). If successful, this would increase the overall value of the wetland by increasing the use values (fish, crops) while maintaining the non-use values (e.g., biodiversity). This introductory chapter provides a background of wetland uses and values, resource trends, integrated farming system concepts, and introduces the study sites and setting of the experimental Fingerpond systems in Kenya. Natural wetlands and uses Wetlands include all forms of landscape characterized by wetness. A number of definitions have been put forward in an attempt to delineate these ecosystems more precisely. The Ramsar Convention on Wetlands of 1971 defines wetlands as “areas of marsh, fen, peat land or water, whether natural or artificial, with water that is static, brackish or salt including areas of marine water, the depth of which at low tide does not exceed 6 metres”. This definition encompasses a wide range of diverse landscapes whereby three inherent components of a wetland are manifested: water, hydric soils and hydrophytic vegetation. Wetlands are often the zone of transition between dry land and a water body (lake, river or sea). Often, they support high primary and secondary productivity and biodiversity. Wetlands have multiple functions and attributes representing values to humanity (Chabwela, 1992; Denny, 1995; Rogeri, 1995; Kairu, 2001). They not only support a rich diversity of flora and fauna but also support the human populations living around them through provision of goods and services. Wetlands are indeed the lifeline for the riparian communities (Silvius et al., 2000). In many developing countries, including those in sub-Saharan Africa, living around a wetland is considered a blessing. Despite being associated with endemic diseases such as malaria and schistosomiasis and livestock parasites such as liver flukes, wetlands provide food for the people and pasture for the livestock during periods of scarcity. For decades, communities at the edges of natural wetlands have cultivated vegetables to meet the household’s demands during the dry season and to augment cash income through market sales. Livestock graze along the wetland margins. Table 2 FINGERPONDS 1.1 shows the economic values of some African wetlands and their contribution to agriculture and fish production. Estimates from West and Central Africa show that the main rivers and floodplains in the region produce an annual fish catch of about 570,000 tonnes and provide employment for about 0.5 million people (Béné, 2005). The diversity of resources explains why Lake Victoria and its catchment can support over 30 million people (Bugenyi, 2001).
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