Green Turtle Conservation Project Final Scientific Report
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This report is published in partnership with MRF GREEN TURTLE CONSERVATION PROJECT FINAL SCIENTIFIC REPORT ARABIAN REGION ABOUT EMIRATES NATURE-WWF Emirates Nature-WWF is a UAE environmental non-governmental organisation, established in 2001 under the patronage of H.H. Sheikh Hamdan bin Zayed Al Nahyan, Ruler’s representative in Al Dhafra Region and Chairman of Environment Agency - Abu Dhabi (EAD). For almost two decades, Emirates Nature–WWF has been a prominent and active partner in environmental conservation in the region. Being part of the global WWF network, which has a 50-year legacy, Emirates Nature-WWF has implemented several conservation and education projects in the region since 2001. Emirates Nature-WWF works federally and in the region with offices in Abu Dhabi, Dubai and Fujairah and is governed by a local board of directors. ABOUT THE MARINE RESEARCH FOUNDATION (MRF) The Marine Research Foundation is non-profit research foundation based in Kota Kinabalu, Malaysia and is incorporated under the Malaysian Trustees Act of 1951. Established to further the understanding of marine ecosystems and their associated diverse flora and fauna in Southeast Asia and other Indo-Pacific sites, the Foundation carries out a number of projects related to biodiversity assessment and conservation and seeks to provide management-oriented solutions to Government administrations and conservationists. EWS-WWF DISCLAIMER The designation of geographical entities in this report, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of Emirates Nature- WWF concerning the legal status of any country, territory, or area, or of its authorities or concerning the delimitation of its frontiers or boundaries. PROJECT PARTNERS Published in December 2019 by Emirates Nature in Association with WWF (Emirates Nature-WWF), Abu Dhabi, United Arab Emirates For more information please visit: www.emiratesnaturewwf.ae: Email: [email protected] Text: © 2019 Emirates Nature-WWF & Marine Research Foundation Cover photograph: © Emirates Nature-WWF and Nicolas Pilcher, Marine Research Foundation Any reproduction in full or in part of this publication must acknowledge the above mentioned published as copyright holders and use the suggested citation below. Pilcher NJ, C.J Rodriguez-Zarate, M Antonopoulou. 2019. Green Turtle Conservation Project 2016-2019: Final Scientific Report. Emirates Nature-WWF. Abu Dhabi, United Arab Emirates. 78 pp. GREEN TURTLE CONSERVATION PROJECT | FINAL SCIENTIFIC REPORT CONTENTS 3. RESULTS 19 3.1 Data Quality & Limitations 19 3.2 Tracking Data Longevity 20 List of Tables vi 3.3 Turtle Morphometrics 22 List of Figures vi 3.4 Sex Ratios & Age Classes 23 Executive Summary viii 3.5 Proportion of Adult Turtles Ready to Breed 24 1. INTRODUCTION 1 3.6 Migrations 25 1.1 Conservation Status of Green Turtles 2 3.6a Nesting Migrations 31 1.2 Threats to Sea Turtles 4 3.6b Post-Nesting Migrations 32 1.3 Ecological Roles of Sea Turtles 5 3.6c Foraging–Nesting–Foraging Migration Loops 34 1.4 Sea Turtle Life Cycle 6 3.6d Looping Migrations 36 1.5 Project Rationale 7 3.6e Courtship Migrations 38 1.6 Geographical Scope 8 3.7 Foraging Grounds 39 1.7 Project Objectives 9 4. DISCUSSION 42 1.8 Project Partners 9 4.1 Conservation Status 43 2. METHODS 10 4.2 Population Dynamics 44 2.1 Project Locations 11 4.3 Data Quality and Interpretation 45 2.2 Turtle Capture and Selection 12 4.4 Migration Behaviour 46 2.3 Satellite Transmitter Attachment Protocols 14 4.5 Nesting Habitats 49 2.4 Data Acquisition & Processing 15 4.6 Foraging Ground Extent 49 2.5 Data Analysis & Filtering 16 4.7 Important Turtle Areas (ITAs) 50 2.5.a Stage-States 17 4.8 Overlap of Foraging Grounds with Mapped Seagrass Habitat 51 2.5.b GIS Mapping & Home Range Density Analysis 17 5. PROJECT VALUES 52 2.5.c Habitat Bathymetry 18 5.1 Potential Conservation / Management Areas 52 5.2 Data Uses & Contributions 56 6. CONCLUSIONS 58 7. ACKNOWLEDGEMENTS 60 ANNEX A. INDIVIDUAL MIGRATION TRACKS 61 EMIRATES NATURE–WWF GREEN TURTLE CONSERVATION PROJECT | FINAL SCIENTIFIC REPORT Figure 6. Affixing a satellite transmitter to Figure 18: Complete movement track (left) Figure 29: Relationship between location LIST OF TABLES a green sea turtle using epoxy. 14 and close up (right) of final foraging ground markers and seagrass habitats for green for green turtle 163501. 34 turtles tracked during the Green Turtle Figure 7. An example of a ‘heat ramp’ Table I. Turtle tracking metadata 2016- Project. Top panel: clear use of seagrass depiction of location point density for Figure 19: Complete movement track (left) 2019. Deployment locations: BT = Bu habitats by turtles at Bu Tinah; Bottom foraging turtles off Ras Al Khaimah, with and close up (right) of final foraging ground Tinah; RAK = Ras Al Khaimah; panel: lack of overlap between location the most dense accumulation of points in for turtle 160246. 34 RAH = Ras Al Hadd. 20 markers and seagrass habitats between Abu the red zone and the least accumulation of Figure 20. Migration loops for three Al Abyad and Al Mirfa. 51 Table II. Summary of curved carapace points out toward the blue and turtles deployed from Bu Tinah in 2018 that length for different age classes and purple zones. 18 Figure 30. Filtered location points off nested in Oman. 35 sex groups among green turtles. 22 the coast of Ras Al Khaimah in relation to Figure 8. Fine-scale bathymetry of the Figure 21: Looping movements by green the proposed Khor Mahzani reserve (while Table III. Summary of age class structure southwestern Arabian Gulf, depicting the sea turtles in the Arabian Gulf that did not at present the exact boundaries remain and male : female distribution among green 20 m (grey), the 10 m (blue), and the 8 stop at either secondary foraging grounds, unknown, the area highlighted in red turtles. 23 m depth contours (red). Green polygons courtship areas or nesting sites. 37 encompassed the general area represent known and mapped Table IV. Proportion of male and in question) 54 female turtles in breeding condition by seagrass habitats. 18 Figure 22: Movements of turtles 169433 (left) and 169436 (right) that may be Figure 31. Filtered location points for Ras deployment year. 24 Figure 9. Age class and sex ratios for green indicative of courtship areas. 38 Al Khaimah foraging turtles indicating use turtles. Patterned lines represents males. Table V. Proportional capture of turtle age of the waters west of Al Marjan island. 54 classes by location. 44 Green = adult; Yellow = subadult; Figure 23: Location markers for turtles in Orange = juvenile. 23 the vicinity of Marawah Marine Biosphere Figure 32. Filtered location points off the Reserve between 2016 and 2019. Light blue coast of Abu Dhabi indicating substantial Figure 10. Proportion of adult turtles in shape depicts the Reserve and the dense use of the waters off Saadiyat Island. 55 breeding condition. Orange = female; Blue accumulation of points is close to = male. 24 Figure 33. Filtered location points by five Bu Tinah. 39 turtles off the coast Abu Dhabi highlighting Figure 11. Composite graphic of all Figure 24: Foraging area location all use of waters around Abu Al Abyad Island. LIST OF FIGURES post-nesting migrations from Oman (6) markers off Ras Al Khaimah showing two Green line marks the eastern boundary of Figure 1: Generalised life cycle of sea and movements within and from foraging important feeding areas (clusters). 40 the Marawah Marine turtles. 6 grounds from Ras Al Khaimah (6) and Bu Biosphere Reserve. 55 Figure 25: Locations of foraging grounds Figure 2. Geographical scope of the Green Tinah (12). Thin blue line depicts the 10m off Ras Al Khaimah Top panel: raw data Turtle Project between 2016 and 2019. depth contour. 26 showing all points from foraging turtles. Key nesting sites depicted include Ras Al Figure 12. Migration tracks for 10 turtles Bottom panel: 90% home range (50.1 km2) Hadd in Oman (green circle), Karan & deployed from Bu Tinah and Ras Al and 30% core habitat (1.84 km2). 41 Jana Islands in Saudi Arabia, and Mukalla Khaimah in 2017. Thin blue line depicts the in Yemen (black circles). Key foraging 10m depth contour. 27 Figure 26: Northwest movements of male grounds where transmitters were deployed green turtle 169440 from Bu Tinah in Figure 13. Migration tracks for 11 turtles include Ras Al Khaimah (yellow circle) Abu Dhabi. 47 deployed from Bu Tinah and Ras Al and Bu Tinah (red circle) in the United Khaimah in 2018. Thin blue line depicts the Figure 27: An example of sea surface Arab Emirates. Key foraging destinations 10m depth contour. 28 temperatures in the Gulf on (clockwise from identified through this project include top left) 03, 06, 09 and 12 September 2019 the Gulf of Kutch in India and the Dahlak Figure 14. Migration tracks for five turtles indicating a lack of temperature gradient archipelago in Eritrea. Country names point deployed at Bu Tinah in 2019 (blue line during the looping migration by to the general location and do not constitute depicts the 10m depth contour). 30 turtle 169443. 48 any indication of political borders. 8 Figure 15. Migration tracks for six turtles Figure 28: Location points from all Figure 3. An aerial view of Bu Tinah Island deployed from Bu Tinah in 2018 that nested turtles tracked in the southwest Arabian – Marawah Marine Biosphere Reserve, in Oman (partial track for turtle 170124 is Gulf between 2016 and 2019. Movement looking eastward at sunrise. 11 excluded for simplicity). Depth contours are lines have been removed for clarity. Red shown for 10m (blue) and 20m (grey). 31 Figure 4. Catching sea turtles on foraging markers: 2016 deployments; Blue markers: grounds off Bu Tinah.