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In Maputo Bay

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In Maputo Bay 1 Aspects of the Biology, Ecology and Fishery of the Beaked Clam 2 Eumarcia paupercula (Holten, 1802), in Maputo Bay 3 Eulália D. Mugabe 4 This thesis is submitted in fulfilment of the degree of Doctor of Philosophy 5 Department of Biological Sciences, Faculty of Science 6 University of Cape Town University of Cape Town 7 Submission date: 19th August 2015 8 Corrections submitted: 31st May 2016 9 Supervisor: Emeritus Prof. Charles L. Griffiths i The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or non- commercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. University of Cape Town 10 For Domingos Mugabe and Felismina Sitoi 11 “My dearly beloved parents... my major strength” ii 12 Declaration 13 I, Eulália Mugabe, hereby declare that I know the meaning of plagiarism and that 14 all of the work presented in this thesis is my own, except where otherwise stated 15 and acknowledged in the text. This thesis has not been submitted in whole or in 16 part for a degree at any other university. 17 Signed: Signature removed 18 Date: 19 19th August 2015 iii 20 Contents 21 Dedication .................................................................................................................................................... ii 22 Declaration.................................................................................................................................................. iii 23 Acknowledgements .................................................................................................................................... vi 24 Abstract ..................................................................................................................................................... viii 25 List of Acronyms ........................................................................................................................................ ix 26 CHAPTER 1: INTRODUCTION ............................................................................................................ 10 27 Introduction to the Veneridae ................................................................................................................. 11 28 Clams fisheries globally .......................................................................................................................... 21 29 Social aspects of small-scale clam fisheries ........................................................................................... 27 30 Review of some biological aspects of clams .......................................................................................... 30 31 Outline of chapters .................................................................................................................................. 36 32 CHAPTER 2: MAPUTO BAY, STUDY SITE AND GENERAL METHODS ................................... 38 33 Introduction ............................................................................................................................................. 38 34 General Methods ..................................................................................................................................... 51 35 CHAPTER 3: SPATIAL AND TEMPORAL PATTERNS IN DENSITY AND SIZE 36 DISTRIBUTION OF Eumarcia paupercula IN MAPUTO BAY .......................................................... 55 37 Introduction ............................................................................................................................................. 55 38 Methods .................................................................................................................................................. 60 39 Results ..................................................................................................................................................... 62 40 Discussion ............................................................................................................................................... 75 41 Conclusion .............................................................................................................................................. 83 iv 42 CHAPTER 4: SOCIO-ECONOMIC ASPECTS OF Eumarcia paupercula COLLECTION ........... 84 43 Introduction ............................................................................................................................................. 84 44 Methods .................................................................................................................................................. 87 45 Results ..................................................................................................................................................... 91 46 Discussion ............................................................................................................................................. 104 47 Conclusion ............................................................................................................................................ 113 48 Appendix: Questionnaire ...................................................................................................................... 115 49 Chapter 5: REPRODUCTIVE BIOLOGY OF Eumarcia paupercula ............................................... 117 50 Introduction ........................................................................................................................................... 117 51 Methods ................................................................................................................................................ 120 52 Results ................................................................................................................................................... 123 53 Discussion ............................................................................................................................................. 127 54 Conclusion ............................................................................................................................................ 134 55 CHAPTER 6: GROWTH ESTIMATIONS OF Eumarcia paupercula .............................................. 135 56 Introduction ........................................................................................................................................... 136 57 Methods ................................................................................................................................................ 139 58 Results ................................................................................................................................................... 147 59 Discussion ............................................................................................................................................. 154 60 Conclusion ............................................................................................................................................ 168 61 Chapter 7: SYNTHESIS AND MANAGEMENT RECOMMENDATIONS .................................... 169 62 Management recommendations ........................................................................................................... 170 63 Further research directions .................................................................................................................... 173 64 REFERENCES ........................................................................................................................................ 175 65 v 66 Acknowledgements 67 I wish to acknowledge the contributions of the following persons and entities in my effort to 68 complete this thesis: 69 Clam collectors: My huge khanimambo (thank you) for granting me interviews and openly 70 sharing your stories and daily experiences on clam digging. Thank you also for contributing to 71 the growth experiment by spreading the word about the on-going work at Costa do Sol. 72 Centro Comunitário de Pescas (CCP) of Costa do Sol and its president, Mr Rafael Pacule, for 73 assistance provided. 74 Emeritus Professor Charles Griffiths, my supervisor, for his support, constructive criticism and 75 encouragement. Professor Adriano Macia, my co-supervisor at the initial stages of this project 76 and mentor, for assisting with logistics in Maputo. Without the guidance of both this project 77 would not have been possible. Thank you. 78 “Eumarcians”, for making our sampling events possible and memorable. Sara Tembe and 79 Carlota Amoda for assistance with sampling and processing; and Dona Flora for invaluable 80 mediation with collectors and for helping with identifying clam grounds around Maputo Bay. 81 This project would not have been the same without you. 82 Department of Biological Sciences at the Eduardo Mondlane University (DCB-UEM) for the 83 facilities provided in the Marine and Aquatic Ecology Lab and B8. Special thanks to João 84 Tsimbane, João Cuna, Santos Mucave and Luciano Cuna for the technical assistance provided. 85 The completion of this thesis is also in part the result of collective efforts from numerous people 86 during the four-year duration project. Dr Sergio Rosendo assisted with the interview design and 87 provided comments on the socio-economic aspect of the study. Dr Dawit Yemane assisted
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