Pond aquaculture spatial distribution, production and productivity determinants in Ghana Iris Ekua Mensimah Fynn Thesis submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Master of Science In Fisheries and Wildlife Emmanuel A. Frimpong, Chair George W. Norton Kathleen A. Alexander November 18th, 2014 Blacksburg, Virginia Keywords: Fish farming, production, pond productivity, site suitability, maps, aquaculture development, Ghana, sub-Saharan Africa Copyright 2014, Iris Ekua Mensimah Fynn Pond aquaculture spatial distribution, production and productivity determinants in Ghana Iris Ekua Mensimah Fynn Abstract The choice of a suitable site for any aquaculture practice is a critical decision to make since it has a large impact on the economic profitability of the venture, considering the fact that location defines the amount of capital needed, production costs, yield and access to market. The limited public and private sector support for small-scale aquaculture can be optimized if farms are zoned into areas with relatively similar performance and needs. Considering the high rate at which aquaculture is increasing globally and its consequent impact on the environment, it is projected that improvements will be made in the practices employed in aquaculture. As these improvements are made, there is the need for the review of the location of aquaculture infrastructure and services in order to increase the productivity of the sector. Also, aquaculture statistics such as location of farms and production estimates are fundamental to policy making and development planning at both national and global levels. Aquaculture statistics are however chronically scanty or unreliable in developing countries such as Ghana. Thus, the goal of this study was to show the relative suitability of areas in Ghana for aquaculture and identify the key variables to be considered in the development (including improvement of existing farms) of the aquaculture sector of the country. I used satellite imagery and GIS data in combination with field observations and questionnaires, to develop a map of the feasibility of pond aquaculture in Ghana and provide a reliable estimate of the number of ponds, their areas, productivity and aggregate production in the country. The main factors that have influenced the current distribution of pond aquaculture in Ghana are population density (indicating the availability of markets, input and labor) and proximity to stream and road networks. My results show a gross underestimation of the number of fish ponds in the country and smaller sizes of ponds than existing records suggest. The average water depth of ponds in Ghana is only half of the recommended depth which explained over 80% of the variation in productivity among farms. I estimated the contribution of ponds to domestic fish production to be two to three times what has been previously reported, but still well below the potential. The results of this study will be vital to current national and international efforts to improve aquaculture enterprises in Ghana. iii Acknowledgements I have been given unique opportunities in Virginia Tech since I arrived here in the summer of 2012, for which I am very grateful to God. This thesis does not only represent the work that I learned to do on my own here but the work of amazing people who helped and encouraged me. I am intensely appreciative of my academic supervisor, Emmanuel Frimpong. He has been my greatest cheerleader, my mentor, a father and a great source of motivation. His patience and encouragement when I was low, has driven me to work harder than I thought I could. To me, he is a jack of all trades and a master of all, and my greatest wish is to be as knowledgeable as he is in future. I appreciate the efforts of my academic committee, Dr. George Norton and Dr. Kathy Alexander, in reviewing my thesis and providing useful contributions to make this study better. I am thankful to all members of the Frimpong team especially Brandon Peoples and Jian Huang for their very necessary suggestions. I am grateful to Yaw Ansah for his willingness to share his field data with me. Dawn Mercer and Caitlin Worsham were extremely helpful with data organization. This work will be incomplete without the help of Gifty Anane-Taabeah, Abigail Tachie and Michael Sasu in the field. This project was partly funded by USAID’s AquaFish Innovation Lab, in collaboration with Virginia Polytechnic Institute and State University, USA and Kwame Nkrumah University of Science and Technology, Ghana. Special thanks goes to Edward Agyapong for his encouragement and support throughout this study. I am grateful for the support and company of my dad, Kojo Fynn. iv Attribution Chapters 1 and 2 are co-authored by Emmanuel Frimpong. Emmanuel’s contributions to the papers include assistance in developing the conceptual framework, evaluation of the analysis, and editing the manuscripts for publication. The manuscripts for both Chapters 1 and 2 are in preparation to be submitted to journals. The manuscripts will be submitted to the International Journal of Sustainable Development and World Ecology and Food Policy, respectively. v Table of contents Abstract ........................................................................................................................................................ ii Acknowledgements .................................................................................................................................... iv Attribution ................................................................................................................................................... v List of Tables ............................................................................................................................................ viii List of Figures ............................................................................................................................................. ix General Introduction ................................................................................................................................... xi Chapter 1: Factors that drive aquaculture and the suitability of districts for aquaculture in Ghana ....... 1 Abstract ........................................................................................................................................................ 1 Introduction .................................................................................................................................................. 3 Methods ........................................................................................................................................................ 5 Study area ................................................................................................................................................. 5 Methodology ............................................................................................................................................. 6 Stream Network ........................................................................................................................................ 7 Markets ..................................................................................................................................................... 8 Roads ......................................................................................................................................................... 8 Elevation and Slope ................................................................................................................................... 9 Population ................................................................................................................................................. 9 Soil ............................................................................................................................................................. 9 Data Analysis........................................................................................................................................... 10 Stream Network ...................................................................................................................................... 12 Markets ................................................................................................................................................... 13 Elevation and Slope ................................................................................................................................. 13 Roads ....................................................................................................................................................... 13 Soil ........................................................................................................................................................... 14 Population, Rural Market and Urban Market ......................................................................................... 14 Determining which variables were most influential in location of pond aquaculture ............................ 15 Determining which districts were most suitable for aquaculture ........................................................... 16 Results......................................................................................................................................................... 17 Discussion ................................................................................................................................................... 20 Stream Network for Ghana ..................................................................................................................... 21 Impact of the stream orders on fish pond locations ............................................................................... 22 vi Slope and Elevation ................................................................................................................................. 23 Soil ........................................................................................................................................................... 24 Roads ...................................................................................................................................................... 25 Market and Population ........................................................................................................................... 25 Raster analysis and calculations ............................................................................................................. 27 Suitable areas for aquaculture in Ghana ................................................................................................ 28 Conclusion .................................................................................................................................................. 29 References .................................................................................................................................................. 51 Chapter 2: Estimating Total Production Capacity of Ponds in Ghana ...................................................... 56 Abstract ...................................................................................................................................................... 56 Introduction ................................................................................................................................................ 58 Methods ...................................................................................................................................................... 61 Study Area ............................................................................................................................................... 61 Field Methods .......................................................................................................................................... 62 Data analysis ........................................................................................................................................... 63 Measuring Productivity ........................................................................................................................... 67 Depth as a measure of productivity ........................................................................................................ 68 Determining correlation between reported data, GIS measurements and field measurements ............ 68 Results......................................................................................................................................................... 69 Discussion ................................................................................................................................................... 71 GIS in Aquaculture ................................................................................................................................... 74 Productivity of fish farms in Ghana ......................................................................................................... 75 Influence of pond water depth on the productivity of farms .................................................................. 76 Conclusion .................................................................................................................................................. 77 References .................................................................................................................................................. 90 Summary and Recommendations .............................................................................................................. 92 Additional References .............................................................................................................................. 110 Appendix A ............................................................................................................................................... 111 vii List of Tables Table 1.1 Summary features of major themes used in site suitability and planning analysis .................... 32 Table 1.2 Soils of Ghana ranked according to suitability for aquaculture .................................................. 38 Table 1.3 Urban and Rural Market. * represents what was reported in Asmah (2008). All others were inferred or calculated…………………………………………………………………………………………………………………………….41 Table 1.4. Suitability of districts in southern Ghana for aquaculture………………………………………………………47 Table 2.1. Estimated number and area of ponds in southern Ghana………………………………………………………80 Table 2.2. Comparative means of the productivity of farmers in Ghana…………………………………………………84 Table 2.3. Results of the regression showing the relationship between depth and productivity of ponds in Ghana. The low p-value of 0.00158 shows that there is a strong quadratic relationship between Depth and Productivity…………………………………………………………………………………………………………………………………….89 Table 3.1. Degree of constraints faced by districts that are highly suitable for aquaculture in Ghana….105 viii List of Figures Figure 1.1. A map of Ghana showing the ten regions and their capitals. Ghana’s neighboring countries are also shown. The south of Ghana is bordered by the Gulf of Guinea. ................................................... 31 Figure 1.2. Developing a spatial framework for aquaculture in Ghana. Spatial analysis begins with knowledge of the locations of farms, biophysical and socioeconomic characteristics of locations with and without farms, and basic infrastructure. .................................................................................................... 33 Figure 1.3. Main fish markets in Southern Ghana. Total number of markets used in the analysis is 176 because the district capitals were included as urban markets. .................................................................. 34 Figure 1.4. Road Network of Southern Ghana. The main roads are comparatively fewer than the trails. 35 Figure 1.5. Slope and Elevation of Ghana. The map on the left shows the elevation of the country with the highest elevation recorded in the south and eastern parts of the country. The right map shows that the slope of the country is generally between 0 and 3%. .......................................................................... 36 Figure 1.6. Population per district in Ghana. Highest populations are recorded in the Kumasi and the Accra metropolitan districts........................................................................................................................ 37 Figure 1.7. Stream Network of Ghana. Streams of the highest order are located in the eastern part of the country. ....................................................................................................................................................... 39 Figure 1.8. Ranking the soil types in Ghana according to their suitability for aquaculture. The southern and western parts of the country generally have the most suitable soil for aquaculture. ........................ 40 Figure 1.9. The importance of the variables used in the analysis as ranked by a boosted regression tree (BRT) model. Markets by far has the highest influence. The relatively low influence of the urban and rural markets justified its exclusion. ........................................................................................................... 41 Figure 1.10. Partial dependency plots of the variables in the boosted regression tree model. The percentages show their relative influence. The graphs also show the thresholds of dependence of pond presence on each variable. ......................................................................................................................... 42 Figure 1.11. Distance from the randomly sampled locations to markets (n=176). Markets here include the district capitals and the six main fish markets. Majority of the areas are within 40 km of markets but a significant number of areas are quite far from markets. ......................................................................... 43 Figure 1.12. Slope in Ghana (n=2187). Few parts of the country recorded high slope percent rise with the average slope percent rise at 3% ................................................................................................................ 44 Figure 1.13. Distance from randomly sampled areas to roads (n=2187). The average distance of the areas sampled to roads is about 5 km. ....................................................................................................... 44 Figure 1.14. The elevation of randomly sampled locations in southern Ghana (n=2187). ........................ 45 Figure 1.15. Southern Ghana’s suitability for Aquaculture. ...................................................................... 46 Figure 1.16. Strategic placement of markets and hatcheries could improve the suitability of areas for aquaculture in Ghana. Markets are the main fish sale points in the country. Hatcheries are the locations where fingerlings are bred. ......................................................................................................................... 50 Figure 2.1. Map of Ghana with colored areas showing the regions included in analysis. The hollow areas practice very little pond aquaculture in Ghana .......................................................................................... 79 Figure 2.2. Explanation of how water depths were recorded. Water depths at the edges of the ponds ix Figure 2.3. The distribution of ponds in the country. The highest number of ponds was recorded in the Ashanti region and the lowest in the Greater-Accra region ....................................................................... 81 Figure 2.4. Representation of the areas of the ponds in the different regions in southern Ghana. The lines drawn on the vertical bars is an indication of the 95% lower and upper confidence boundaries of the estimates .............................................................................................................................................. 82 Figure 2.5. Comparative total area measurements of farms. Farmers report higher pond areas in survey. GIS measurements are similar to field measurements............................................................................... 83 Figure 2.6. Comparative productivity measurements of farms for tilapia. ................................................ 84 Figure 2.7. Comparative productivity measurements of farms for all species combined. ........................ 85 Figure 2.8. Annual Productivity of farms in Ghana (n= 40). ....................................................................... 86 Figure 2.9. Average water depth of ponds in Ghana measured on 39 farms and 114 ponds. The average depth of water in ponds in Ghana was about 0.6 m. ................................................................................. 87 Figure 2.10. Relationship between pond depth and productivity of farms in Ghana (n=25) .................... 88 Figure 3.1. Relationship between the pond density in a district and the suitability of the district for pond aquaculture. Each point represents a district. Generally, the more suitable a district is for pond aquaculture, the more ponds are expected in the district. ...................................................................... 104 Figure 3.2. The effect of low population density on the practice of aquaculture in districts with high suitability for aquaculture in Ghana. ........................................................................................................ 107 Figure 3.3. The effect of low road density on the practice of aquaculture in districts with high suitability for aquaculture in Ghana .......................................................................................................................... 107 Figure 3.4. The effect of forest reserves on the practice of aquaculture in districts with high suitability for aquaculture in Ghana. ......................................................................................................................... 108 Figure 3.5. Improving the production of fish farms across the country by the strategic establishment of hatcheries. ................................................................................................................................................ 109 x