Quantifying the Development of Small-Scale Fisheries on Coral
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QUANTIFYING THE DEVELOPMENT OF SMALL-SCALE FISHERIES ON CORAL REEFS, AND THEIR IMPACT ON HABITATS by Jennifer Coyle Selgrath B.A., Wesleyan University, 2001 M.Sc., San Diego State University, 2006 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Zoology) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2017 © Jennifer Coyle Selgrath, 2017 Abstract Growing human populations place multiple pressures on social-ecological systems, including coastal oceans. However, the effects of long-term and/or overlapping stressors remain poorly understood, particularly over large spatial scales. My dissertation evaluated how pressures from fishing and co-occurring stressors correspond to current ecological conditions in the Danajon Bank, a coral reef ecosystem in the central Philippines. I used long-term local ecological knowledge (LEK) to map fishing practices (1950-2010) and high spatial resolution satellite imagery to map coastal habitats. This innovative suite of methods enabled me to examine patterns over broader spatial scales and longer time periods than those usually assessed. I met five primary objectives: (1) quantify the spatio-temporal dynamics of fishing effort and gear use; (2) examine the influence of fisheries governance; (3) map the spatial distribution of benthic (seafloor) habitats; (4) model the spatial distribution of living corals in relation to co-occurring stressors and biophysical conditions; and (5) explore the conservation implications of these relationships. While individuals’ fishing practices were fairly consistent over time, this small-scale fishery has changed dramatically. First, total fishing effort (days per year fished by all fishers) accelerated between 1960 and 2010 because of rapid growth in the number of fishers. Aggregate fishing effort increased almost 2.5-fold and spatially-explicit fishing effort increased over 20-fold. Second, the areal extent of fishing grounds expanded greatly. Third, use of fishing gears changed over time. Diversity of fishing gears increased, as did fishing effort with destructive, active, and non-selective gears. Considering the timing of these changes, I found a lasting influence of fishing policies, and small improvements in the sustainability of fishing gears following ii implementation of co-management. Finally, I found that the probability that an area supported living corals was affected by fishing through both long- & short-term mechanisms, and I documented strong coral-landscape relationships. My research demonstrates that to strengthen ocean conservation, it will be essential to reduce the frequency and intensity of stressors, remove some areas from exploitation, foster resilience traits of ecosystems, gather data to better understand systems, and strengthen the institutions that can support these endeavors. iii Lay Summary Fishing provides an essential source of protein for half a billion people, but many fisheries damage ocean ecosystems including coral reefs. I demonstrated that small-scale fisheries in the Philippines shifted from benign to damaging through several mechanisms and had long-term effects on corals. Fishing effort increased 2.5-fold overall, and over 20-fold in some locations. Increases in total fishing effort were driven by a growing number of fishers, rather than by changes in individual fishers’ behaviour. I documented a growing diversity and spatial overlap of fishing gears, with a growing amount of fishing effort dependent upon destructive, non-selective, and illegal fishing gears. Living corals were less prevalent in places that had experienced heavy fishing during the past 30 years, particularly where coral reefs were close to large villages. In contrast, corals were more likely to be present in deeper locations and in areas that were protected from fishing. iv Preface This thesis is comprised of four scientific papers of which I am (or will be) the lead author. I set project scope in collaboration with my first advisor, Dr. Amanda Vincent, with further influence from Dr. Sarah Gergel, after she became my co-advisor. I was primarily responsible for conceptualization, experimental design, collecting information (with help from a team of research assistants), data management, data analysis, interpretation of results, and manuscript preparation. My co-advisors, Dr. Amanda Vincent and Dr. Sarah Gergel were instrumental in helping me improve and refine the questions for each chapter. Additionally they assisted with interview design, provided feedback on data analyses and interpretation, and engaged heavily with the writing of the chapters. Dr. Amanda Vincent facilitated my research in the Philippines, and connected me with the Project Seahorse Foundation team (now ZSL Philippines), which acted as my local partner. For Chapter 4, Dr. Chris Roelfsema created the decision rules to classify the satellite images, provided feedback on analysis, and edited the manuscript. Dr. Roelfsema suggested the addition of the cost analysis. For Chapter 5, Dr. Gergel provided key insights about resilience. I raised the bulk of the funding for fieldwork, and received additional support from Dr. Vincent and Dr. Gergel. Dr. Heather Koldewey (of ZSL, UK) raised a portion of the funding for Chapter 4. Dr. Phillip Molloy provided invaluable help in developing my understanding of how to manage and analyze time-series of data. Carl Walters helped me identify how to estimate trends in spatial fishing effort. v Two publications have resulted from this research: Chapter 3: Selgrath, J.C., Gergel, S.E., and Vincent, A.C.J. (2017) “Incorporating spatial dynamics greatly increases estimates of long-term fishing effort: A participatory mapping approach.” ICES Journal of Marine Science. Chapter 4: Selgrath, J.C., Roelfsema, C., Gergel, S.E., and Vincent, A.C.J. (2016) Mapping for Coral Reef Conservation: Comparing the Value of Participatory and Remote Sensing Approaches. Ecosphere 7(5): e01325. One chapter has been accepted to a journal with major revisions: Chapter 2: Selgrath, J.C., Gergel, S.E., and Vincent, A.C.J. “Shifting Gears: Diversification, intensification and effort increases of small-scale fisheries” (Accepted with major revisions) PLOS One. Chapter 5 will be submitted to a leading scientific journal as a co-authored paper with my advisors S.E. Gergel and A.C.J. Vincent. All fieldwork in this dissertation was approved by UBC’s animal care committee (A07-0076- R004) and UBC’s Human Behavioural Research Ethics Board (H07-00577) and (H06-80484). vi Table of Contents Abstract .......................................................................................................................................... ii Lay Summary ............................................................................................................................... iv Preface .............................................................................................................................................v Table of Contents ........................................................................................................................ vii List of Tables .............................................................................................................................. xvi List of Figures ...............................................................................................................................xx List of Symbols ......................................................................................................................... xxvi List of Abbreviations ............................................................................................................. xxviii Acknowledgements .................................................................................................................. xxix Dedication ................................................................................................................................. xxxi Chapter 1: Introduction ................................................................................................................1 1.1 Rationale ......................................................................................................................... 1 1.2 Background and context ................................................................................................. 3 1.3 Case study ..................................................................................................................... 10 1.4 Context for the field study ............................................................................................ 14 1.5 Research questions ........................................................................................................ 14 1.6 Thesis outline ................................................................................................................ 15 1.6.1 Chapter 2: Shifting gears: Sixty years of diversification, intensification, and effort increases in small-scale fisheries .......................................................................................... 15 1.6.2 Chapter 3: Incorporating spatial dynamics greatly increases estimates of long-term fishing effort: A participatory mapping approach ................................................................ 16 vii 1.6.3 Chapter 4: Mapping for coral reef conservation: Comparing the value of participatory and remote sensing approaches ......................................................................