Exploitation of Marine Turtles and Elasmobranchs in Madagascar
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Exploitation of marine turtles and elasmobranchs in Madagascar Submitted by Frances Kate Humber to the University of Exeter as a thesis for the degree of Doctor of Philosophy in Biological Sciences in June 2015. This thesis is available for Library use on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. I certify that all material in this thesis which is not my own work has been identified and that no material has previously been submitted and approved for the award of a degree by this or any other University. Signature: 1 Abstract Small-scale fisheries (SSF) are poorly documented, yet 90% of the 120 million employed in capture fisheries work in the SSF sector and >1 billion people globally rely on fish as an important source of protein. There is a lack of data on the status of the majority of fisheries in Madagascar owing to the difficulty in surveying the vast coastline and large number of small-scale fishers. In Madagascar, marine turtles and elasmobranchs are important culturally and as sources of income and food for many small-scale fishers. However, very little data exist on the status of these two animal groups. The five chapters of this thesis intend to increase our understanding of the status of marine turtles and elasmobranchs in Madagascar. This is achieved through the assessment of the fisheries, legislation and in the case of turtles, the nesting population. I also document community-based methods for monitoring fisheries and marine turtle nesting, that are easily replicable for gathering data across remote regions. Results show that the turtle fishery in Madagascar appears to have remained at the same level since the 1970s, despite being illegal since the 1990s, with landings estimated to be approximately 10,000 to 16,000 turtles.year-1. To further contextualise the take of turtles in Madagascar, by carrying out a global review, I estimate that the worldwide legal take in turtle fisheries to be over 42,000 turtles.year-1. Contrary to reports from fishers, actual numbers of elasmobranchs (the majority of which are sharks) taken by the traditional (non- motorised) fishery has not declined. Results support previous reports that fishing effort has increased, as well changes in fishing gears, to account for declining catch per unit effort (CPUE) to maintain shark landing numbers. Furthermore, the size of some shark species has significantly declined, even across this study. Community-based turtle nesting monitoring and protection in 2 western Madagascar revealed a small, yet potentially significant, nesting population. Across the 17 current nesting sites recorded, the majority of nesting populations in Madagascar have <50 nests.year-1. A further >40 historic nesting sites were recorded. Community-led monitoring methods not only helped to fill a data gap, but were also found to reduce loss of nests through human disturbance. Misinterpretations, poor enforcement and gaps in current legislation mean that both marine turtles and elasmobranchs are effectively unprotected from overexploitation. This thesis provides recommendations for improved legislation and management of both groups of species and demonstrates that participatory monitoring methods can not only reduce data deficiency, but enhance locally-led management and protection, and increase Madagascar’s capacity for improved management and conservation. 3 List of contents Abstract .................................................................................................................2 Acknowledgements ...............................................................................................5 List of Tables and Figures .....................................................................................6 List of Abbreviations, Acronyms and Conversions .............................................. 26 Author’s declaration of contributions to co-authored chapters/research papers .. 27 Introduction.......................................................................................................... 30 Chapter 1: Using community members to assess artisanal fisheries: the marine turtle fishery in Madagascar .................................................................... 42 Chapter 2. So excellent a fishe: a global overview of legal marine turtle fisheries ............................................................................................................... 82 Chapter 3: Assessing the small-scale shark fishery of Madagascar through community-based monitoring and knowledge ................................................... 151 Chapter 4: Placing Madagascar’s marine turtle populations in a regional context using community based monitoring ...................................................... 223 Chapter 5: Endangered, essential and exploited: how extant laws are not enough to protect marine megafauna in Madagascar ....................................... 278 General Discussion ........................................................................................... 354 4 Acknowledgements I would first like to thank the numerous people that have supported me from my colleagues at Blue Ventures Conservation, community members of Madagascar, friends and family, without which this work would not have been possible. Special thanks go to my two supervisors, Annette Broderick and Brendan Godley, for providing guidance, advice and support since 2007. Special thanks also to my particular colleagues at Blue Ventures Conservation, Alasdair Harris, Charlie Gough and Garth Cripps for their support, advice and knowledge. In particular I must thank Thomas Beriziny, a friend and colleague who is no longer with us, but without which much of this work have been impossible due to his relationship with the community in Madagascar, and knowledge of the traditional fisheries. I would like to thank the many fishermen and community data collectors that made this study possible and contributed their time and energy to helping me understand the traditional shark and marine turtle fisheries. Finally I would like to thank those that funded much of this work: The Rufford Foundation, National Geographic Conservation Trust, SeaWorld and Busch Gardens Conservation Fund, British High Commission of Mauritius and The State of the World’s Sea Turtles (SWOT). 5 List of Tables and Figures Chapter 1 Using community members to assess artisanal fisheries: the marine turtle fishery in Madagascar. Table 1. The 12 villages included in the monitoring programme, their population size and the number of months in 2007 during which landed turtles were recorded. The estimated number of turtles landed shows the total if villages had recorded for 12 months. Human population data were from 2006 and 2008 (Epps, 2006; Andriamalala, 2008). Table 2. Breakdown of species of marine turtle landings recorded (1 January– 31 December 2007) with the mean curved carapace length (CCL) and capture method for each species, including loggerhead Caretta caretta and olive ridley Lepidochelys olivacea. No leatherback turtles (Malagasay name: Fano valorozo) were recorded. Table 3. Community member data collectors’ attitudes to changes in the turtle fishery. Table 4. The potential number of turtles landed in artisanal fisheries from data from previous studies. Table 5. Limitations and recommendations for implementing community data collection of turtle harvest. 6 Figure 1. Map showing the location of the 12 villages included in this study and the number of landed turtles recorded. The inset shows the location in Madagascar. Figure 2. Total turtle landings from 1 January to 31 December 2007 for villages that recorded a full year of data. Data from the villages of Morombe, Nosy Lava, Belavenoke and Nosy Hao have been removed. Figure 3. Curved carapace length of green and hawksbill turtles recorded in this study (1 January–31 December 2007). The percentage of potential juveniles and adults at minimum sizes of recorded nesting green (Metcalf et al., 2007) and hawksbill (Alisson, 2008) turtles are shown on the graph. Figure 4. Map showing the location of previous studies on the traditional turtle fishery in Madagascar, the study site (d) and the numbers of turtles estimated in each study. Lengths of boxes are scaled to show the approximate lengths of the coastline covered by the study. *Turtle catch estimated through actual count of landed turtles or carapaces. 7 Chapter 2 So excellent a fishe: a global overview of legal marine turtle fisheries Figure 1. The number of countries or territories that permit the direct take of turtles (as of 1st January 2013) showing type of legislation in place or absence. N = Protection absent; L = Legislation allows for a level of harvest of one or more species of turtles; T = Full protection but traditional hunting exemptions exist; M = Moratorium in place only at present; U = Unable to verify legislation. Figure 2. The current estimate of annual legal take by species (n = 42 countries) (data from 1 January 2010 to 1 January 2013). O. Ridley = Olive Ridley; K. Ridley = Kemp’s Ridley. Figure 3. Estimated current annual legal marine turtle take by country or territory (data from 1 January 2010 to 1 January 2013). Data for the Caribbean (CAR) and Pacific (PAC) regions have been grouped and are shown in further detail in Fig. 4a,b. No take = no known legal or illegal take; Unquantified take = illegal take data found only or take known to occur but no data available. *Country with moratorium. Country