THE UNIVERSITY OF HULL Management of Watergate to Enhance Fisheries In the Nam Kam River System, Thailand being a Thesis submitted for the Degree of Doctor of Philosophy in the University of Hull by Apiradee Hanpongkittikul B.Sc. Fisheries (Kasetsart University) M.Sc. Fisheries Sciences (Kasetsart University) September 2017 TABLE OF CONTENTS Management of Watergate to Enhance Fisheries .................................................... i TABLE OF CONTENTS ............................................................................................. ii LIST OF TABLES ..................................................................................................... vii LIST OF FIGURES ..................................................................................................... x ACRONYMS ............................................................................................................ xiv DECLARATION OF AUTHORSHIP ........................................................................ xv CONFERENCE PRESENTATIONS ...................................................................... xv PART OF THIS WORK HAS BEEN PUBLISH AS ................................................ xvi PART OF THESE WORK HAS BEEN SUBMITTED AS TECHNICAL REPORT .. xvi PARTS OF THIS WORK ARE IN PREPARATION FOR PUBLICATION .............. xvi ACKNOWLEDGEMENT ......................................................................................... xvii ABSTRACT ........................................................................................................... xviii DEFINITION: ........................................................................................................... xix Chapter 1: Introduction ............................................................................................ 1 Background ............................................................................................................. 1 Aims and objectives ................................................................................................ 3 Structure ................................................................................................................. 4 Chapter 2: Literature Review ................................................................................... 6 2.1. Description of the system/ study area ............................................................... 6 2.1.1 The Nam Kam River system ....................................................................... 6 2.1.2 Land used on the vicinity of river ................................................................. 6 2.1.3 The Nam Kam Royal Development project ................................................. 7 2.1.4 Reference river: Songkhram River .............................................................. 9 2.1.5 Diversity and community structure of fishes in the Nam Kam River system. 9 2.2 Migration of freshwater fishes .......................................................................... 10 2.2.1 Migration of fishes in the Mekong River Basin ........................................... 11 2.2.2 Migration of fishes in the Nam Kam River system ..................................... 18 2.3 Hydrological flow in the Mekong mainstream and tributaries ........................... 19 2.3.1 Flood and drought hydrology .................................................................... 22 2.3.2 Influence of hydrological characteristic changes on aquatic biodiversity ... 23 2.4 Impact of dam construction on river systems ................................................... 24 2.4.1 Impact on different habitat types ............................................................... 25 2.4.2 Influence of flow modification on fish populations ...................................... 28 ii 2.4.3 Impact of dam construction on genetic diversity ........................................ 30 2.4.4 Impact of dam construction on fish migration ............................................ 31 2.5 Conclusion ...................................................................................................... 33 Chapter 3: Hydrological change in the Nam Kam River system.......................... 34 3.1 Introduction ..................................................................................................... 34 3.2 Objective ......................................................................................................... 35 3.3 Methodology .................................................................................................... 35 3.3.1 Hydrological data collection and habitat description .................................. 35 3.3.2 Data analysis ............................................................................................ 40 3.4 Results ............................................................................................................ 44 3.4.1 Watergate and fish pass operation in the Nam Kam River system ............ 44 3.4.2 Guidelines for operation ............................................................................ 47 3.4.3 Hydrological changes resulting from watergate operation ......................... 47 3.4.4 Flow and discharge changes .................................................................... 48 3.4.5 Annual water level changes ...................................................................... 59 3.4.6 Habitat characteristics of study sites throughout an annual cycle .............. 62 3.4.7 Rainfall in Nam Kam River Basin .............................................................. 63 3.4.8 Water quality changes .............................................................................. 64 3.4.9 Spatial variation mapping of hydrological alteration at a stream-network scale .................................................................................................................. 66 3.5 Discussion ....................................................................................................... 69 3.5.1 Watergate management in the Nam Kam River system ............................ 69 3.5.2 Impact of watergate operation on hydrological changes of Nam Kam River and its tributary. ................................................................................................. 70 Chapter 4: Population structure and distribution of fish in the Nam Kam River system ..................................................................................................................... 76 4.1 Introduction ..................................................................................................... 76 4.2 Objectives ....................................................................................................... 77 4.3 Methodology .................................................................................................... 78 4.3.1 Sampling and data collection .................................................................... 78 4.3.2 Data analysis ............................................................................................ 79 4.4 Results ............................................................................................................ 80 4.4.1 Hydrology and watergate management during the sampling period .......... 80 4.4.2 Diversity of fishes ...................................................................................... 82 4.4.3 Abundance and fish catches ..................................................................... 85 4.4.4 Spatial variation of fish in the Nam Kam River system and Songkhram River .................................................................................................................. 87 iii 4.4.5 Seasonal variation of fish .......................................................................... 89 4.4.6 Catches and distribution of target species ............................................... 100 4.5 Discussion ..................................................................................................... 101 4.5.1 Do watergate and fish pass operations impact on fish species diversity and population structure in the Nam Kam River system? ........................................ 101 4.5.2 Do watergate and fish pass operations impact on fish distribution? ........ 103 4.5.3 Seasonal variation in fish population structure and watergate operation . 107 4.5.4 Adaptation of fish to hydrological changes and modified habitat in the Nam Kam River system............................................................................................ 109 4.6 Summary ....................................................................................................... 111 Chapter 5: Spawning and nursery grounds in the Nam Kam River system ..... 113 5.1 Introduction ................................................................................................... 113 5.2 Aims and Objectives ...................................................................................... 114 5.3 Methodology .................................................................................................. 115 5.3.1 Sampling and data collection for larval and juvenile fish ......................... 115 5.3.2 Data analysis .......................................................................................... 117 5.4 Results .......................................................................................................... 119 5.4.1 Spatial distribution of larvae and juvenile fish .........................................