Culturing African Lungfish (Protopterus sp) in Uganda: Prospects, Performance in tanks, potential pathogens, and toxicity of salt and formalin by John Kiremerwa Walakira A dissertation submitted to the Graduate Faculty of Auburn University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Auburn, Alabama December 14th, 2013 Keywords: African lungfish, aquaculture, exogenous feed, diseases, Salt and Formalin effects. Copyright 2013 by John Kiremerwa Walakira Approved by Joseph J. Molnar, Co-chair, Professor, Agricultural Economics and Rural Sociology Jeffery S. Terhune, Co-chair, Associate Professor, School of Fisheries, Aquaculture and Aquatic Sciences Ronald P. Phelps, Associate Professor, School of Fisheries, Aquaculture and Aquatic Sciences Curtis M. Jolly, Professor, Agricultural Economics and Rural Sociology Abstract Culturing species resilient to drought and stressful water quality conditions may be a significant part of the future of African aquaculture. Air breathing fishes potentially have a role in low-management culture systems for small farms because dissolved oxygen does not threaten the fish crop. The African lungfish (Protopterus sp) is advantageous because it is: an indigenous fish with good flesh quality, an air-breather, and a biocontrol agent against schistosome vector snails. Wild lungfish stocks are declining and national strategies to protect its natural population are lacking. Lungfish is highly valued as food, has certain nutraceutical benefits and supports livelihoods of many communities in Uganda. A variety of lungfish products on markets include fried pieces (54%), cured/smoked fish (28%), whole fresh gutted fish (10%) and soup (8%). Lungfish products are increasingly found alongside tilapia and Nile perch in rural and urban markets with cured products being exported to Kenya, DRC and Southern Sudan. Its fingerlings are now sold as bait in the Nile perch fishery. Women not only consume lungfish but are actively engaged in its trade. However, some countervailing sociocultural beliefs continue to deter some fish consumers from eating lungfish. Culture performance of wild caught African lungfish fingerlings (9.58 ─ 9.95g) fed at three commercial diets was evaluated. Experimental fish accepted exogenous sinking pellets but marginal increase in average body weight were observed. Mean (± SE) final weight (15.86 ± 0.80g) for fish fed the commercial diet-3 was significantly higher (p < 0.05) than fish which fed ii on diet-1 and diet-2. Specific growth rates (SGR) for diet-2 (0.50 ± 0.06%/d) were significantly higher (p< 0.05) than diet-1 (0.27 ± 0.03%/d), and marginally more (p < 0.05) than diet-2 (0.37 ± 0.04%/d). Feed conversions were similar for fish fed diet-1, 2 and 3. Survivals after an 11-week culture period were relatively low (< 60%) but generally increased (R2 = 0.667, P = 0.0071) with increasing dietary proteins. Diet-3 (57.50 ± 2.85%) had a significant higher survival rate (p < 0.05) than diet-1 (45.83 ± 3.44%) and diet-2 (40.84 ± 2.10%). All water quality parameters were within recommended aquaculture ranges. Poor growth and high mortalities experienced in this study may be due to i) sub-optimum dietary protein levels, ii) cannibalism, iii) disease infections, iii) density, iv) contaminants in the feed and, iv) wrong management protocols. Unless these factors are adequately addressed this fish is not a good aquaculture candidate. Additional studies will be needed to assess the culture potential of African lungfish due to high rates of mortality that occurred in the present study. Common diseases encountered include; bacteria (Aeromonas sp., Flavobacterium columnare and Pseudomonas sp.), fungus (Fusarium spp., Aspergilus sp and Saprolegnia sp) and parasite (Dactylogurus sp, Trichodina sp., Tetrahymena sp, Heterorchis sp. and Cestodes). However, about 60% fungal infections mostly occurred compared to monogenes (9%), tapeworms (25%) and bacteria (6%). Moribund fish were infected with fungal and bacterial infections in the liver, spleen, dermal layer and gastro-intestinal tract. Skin erosion and dermal mycosis were evident in most infected fish but with some indication of regeneration. African lungfish fingerlings (7.78 ± 1.47 g) appear to be sensitive to saline conditions having a LC50 of 2.59 and 1.84 for 24 and 96h, respectively. Lungfish behaves normally at low salt concentrations (0 ─ 1.6 g/L) but become lethargic within 4h when concentrations reach 4 g/L. Juveniles are tolerant to formalin having LC50 of 220.8 and 193.8 mg/L for 24 and 96h, respectively. iii Acknowledgments This study was sponsored by the Aquaculture and Fisheries Collaborative Research Support Program (AquaFish CRSP) under USAID. I would like to thank my advisory committee for their guidance and compassion during my course of studies in Auburn University. Special thanks go to Professors Joseph Molnar and Hilary Egna for their support towards my studies and research in Uganda. I extend my gratitude to National Fisheries Resources Research Institute (Uganda) fraternity for their technical assistance provided. Finally, the comfort and encouragement I received from my family; Rose Nalukwago (Wife), Sons-Mathew Nyanzi and Kevin Mawejje, daughters- Zoe Namuleme and Cindy Ruth Nantume, Mother-Esuka Nakimera, and The Kiremerwa, who constantly sought God‟s intervention, for this time to come. iv Table of Contents Abstract ........................................................................................................................................... ii Acknowledgments.......................................................................................................................... iv Table of Contents ............................................................................................................................ v List of Figures ................................................................................................................................ ix Introduction and Literature Review ............................................................................................ 1 1.0.0 Introduction .................................................................................................................. 1 1.1.0 Problem Statement ........................................................................................................ 3 1.2.0 Objective of the study ................................................................................................... 4 1.2.1 Supporting objectives ................................................................................................... 4 1.2.2 Research questions ....................................................................................................... 4 1.3.0 Significance of the study .............................................................................................. 5 2.0.0 Literature Review ......................................................................................................... 6 2.1.0 Fisheries ........................................................................................................................ 6 2.2.0 Global Aquaculture ....................................................................................................... 7 2.2.1 Aquaculture in Africa ................................................................................................. 10 2.2.2 Fisheries and Aquaculture in Uganda ......................................................................... 11 2.3.0 Climate change ........................................................................................................... 14 2.3.1 Climate change: Fisheries ........................................................................................... 16 2.4.0 Biology of African Lungfish ...................................................................................... 19 2.5.0 Diseases associated with Lungfishes .......................................................................... 26 CHAPTER II ................................................................................................................................. 28 1.0.0 Abstract ....................................................................................................................... 28 2.0.0 Introduction ................................................................................................................ 29 3.0.0 Materials and methods ................................................................................................ 31 3.1.0 Districts covered ......................................................................................................... 32 3.2.0 Assessment of lungfish culture ................................................................................... 33 v 3.3.0 Socio-economics factors ............................................................................................. 33 4.0.0 Results and Discussion ............................................................................................... 33 4.1.0 Lungfish is popular in East Africa .............................................................................. 33 4.2.0 Sources of parent (Brood) stock ................................................................................. 39 4.3.0 African Lungfish Aquaculture .................................................................................... 43 4.4.0 Harvesting and handling methods .............................................................................