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Setyawan E, Erdmann MV, Mambrasar R, Ambafen O, Hasan AW, Izuan M, Mofu I, Putra MIH, Sianipar AB, Constantine R, Stevenson BC, Jaine FRA. Spatial connectivity of reef manta rays across the Raja Ampat archipelago, Indonesia. ROYAL SOCIETY OPEN SCIENCE 2024; 11:230895. [PMID: 38601035 PMCID: PMC11004681 DOI: 10.1098/rsos.230895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 09/22/2023] [Accepted: 02/05/2024] [Indexed: 04/12/2024]
Abstract
The reef manta ray Mobula alfredi is present throughout most island groups that form the Raja Ampat archipelago, Indonesia. The species is protected regionally and nationally and is currently managed as a single homogeneous population within the 6.7 million ha archipelago. However, scientific evidence is currently lacking regarding the spatial connectivity and population structure of M. alfredi within this archipelago. Using network analysis and an array of 34 acoustic receivers deployed throughout Raja Ampat between February 2016 and September 2021, we examined the movements of 72 subadult and adult M. alfredi tagged in seven regions of Raja Ampat. A total of 1094 M. alfredi movements were recorded and were primarily concentrated between nearby receiver stations, highlighting frequent local movements within, and limited long-distance movements between regional acoustic receiver arrays. Network analysis revealed highly connected nodes acting as hubs important for M. alfredi movements. A community detection algorithm further indicated clusters within the network. Our results suggest the existence of a metapopulation comprising three demographically and geographically distinct subpopulations within the archipelago. They also reveal the importance of Eagle Rock as a critical node in the M. alfredi movement network, justifying the urgent inclusion of this site within the Raja Ampat marine protected area network.
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Affiliation(s)
- Edy Setyawan
- Institute of Marine Science, University of Auckland, Auckland1010, New Zealand
| | - Mark V. Erdmann
- Conservation International Aotearoa, University of Auckland, Auckland1010, New Zealand
| | - Ronald Mambrasar
- West Papua Program, Konservasi Indonesia, Sorong, Papua Barat98417, Indonesia
| | - Orgenes Ambafen
- BLUD UPTD Pengelolaan KKP Kepulauan Raja Ampat, Waisai, Papua Barat98417, Indonesia
| | - Abdi W. Hasan
- West Papua Program, Konservasi Indonesia, Sorong, Papua Barat98417, Indonesia
| | - Muhamad Izuan
- West Papua Program, Konservasi Indonesia, Sorong, Papua Barat98417, Indonesia
| | - Imanuel Mofu
- BLUD UPTD Pengelolaan KKP Kepulauan Raja Ampat, Waisai, Papua Barat98417, Indonesia
| | - Mochamad I. H. Putra
- Elasmobranch and Charismatic Species Program, Konservasi Indonesia, Jakarta12550, Indonesia
| | - Abraham B. Sianipar
- School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia6150, Australia
| | - Rochelle Constantine
- Institute of Marine Science, University of Auckland, Auckland1010, New Zealand
- School of Biological Sciences, University of Auckland, Auckland1010, New Zealand
| | - Ben C. Stevenson
- Department of Statistics, University of Auckland, Auckland1010, New Zealand
| | - Fabrice R. A. Jaine
- Integrated Marine Observing System (IMOS) Animal Tracking Facility, Sydney Institute of Marine Science, Mosman, New South Wales2088, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales2109, Australia
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2
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Humble E, Hosegood J, Carvalho G, de Bruyn M, Creer S, Stevens GMW, Armstrong A, Bonfil R, Deakos M, Fernando D, Froman N, Peel LR, Pollett S, Ponzo A, Stewart JD, Wintner S, Ogden R. Comparative population genomics of manta rays has global implications for management. Mol Ecol 2023. [PMID: 37994168 DOI: 10.1111/mec.17220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/24/2023]
Abstract
Understanding population connectivity and genetic diversity is of fundamental importance to conservation. However, in globally threatened marine megafauna, challenges remain due to their elusive nature and wide-ranging distributions. As overexploitation continues to threaten biodiversity across the globe, such knowledge gaps compromise both the suitability and effectiveness of management actions. Here, we use a comparative framework to investigate genetic differentiation and diversity of manta rays, one of the most iconic yet vulnerable groups of elasmobranchs on the planet. Despite their recent divergence, we show how oceanic manta rays (Mobula birostris) display significantly higher heterozygosity than reef manta rays (Mobula alfredi) and that M. birostris populations display higher connectivity worldwide. Through inferring modes of colonization, we reveal how both contemporary and historical forces have likely influenced these patterns, with important implications for population management. Our findings highlight the potential for fisheries to disrupt population dynamics at both local and global scales and therefore have direct relevance for international conservation of marine species.
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Affiliation(s)
- Emily Humble
- Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Edinburgh, UK
- The Manta Trust, Catemwood House, Dorset, UK
| | - Jane Hosegood
- The Manta Trust, Catemwood House, Dorset, UK
- Molecular Ecology and Evolution Group, Bangor University, Bangor, UK
| | - Gary Carvalho
- Molecular Ecology and Evolution Group, Bangor University, Bangor, UK
| | - Mark de Bruyn
- Molecular Ecology and Evolution Group, Bangor University, Bangor, UK
- Australian Research Centre for Human Evolution, Griffith University, Nathan, Queensland, Australia
| | - Simon Creer
- Molecular Ecology and Evolution Group, Bangor University, Bangor, UK
| | | | - Amelia Armstrong
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Ramon Bonfil
- Océanos Vivientes AC, Mexico City, Mexico
- Consejo Nacional de Humanidades Ciencia y Tecnología (CONAHCyT), Mexico City, Mexico
- El Colegio de la Frontera Sur, Unidad Chetumal, Chetumal, Mexico
| | - Mark Deakos
- Hawai'i Association for Marine Education and Research, Lahaina, USA
| | - Daniel Fernando
- The Manta Trust, Catemwood House, Dorset, UK
- Blue Resources Trust, Colombo, Sri Lanka
| | - Niv Froman
- The Manta Trust, Catemwood House, Dorset, UK
| | - Lauren R Peel
- The Manta Trust, Catemwood House, Dorset, UK
- Save Our Seas Foundation - D'Arros Research Centre, Geneva, Switzerland
- School of Biological Sciences, Oceans Institute and Oceans Graduate School, The University of Western Australia, Crawley, Western Australia, Australia
| | | | - Alessandro Ponzo
- Large Marine Vertebrates Research Institute Philippines, Jagna, Philippines
| | - Joshua D Stewart
- The Manta Trust, Catemwood House, Dorset, UK
- Ocean Ecology Lab, Marine Mammal Institute, Department of Fisheries, Wildlife & Conservation Sciences, Oregon State University, Newport, Oregon, USA
| | - Sabine Wintner
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Rob Ogden
- Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Edinburgh, UK
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3
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Butler G, Ross K, Beaman J, Hoepner C, Baring R, Burke da Silva K. Utilising tourist-generated citizen science data in response to environmental challenges: A systematic literature review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 339:117889. [PMID: 37058928 DOI: 10.1016/j.jenvman.2023.117889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 03/06/2023] [Accepted: 04/05/2023] [Indexed: 05/03/2023]
Abstract
There has been a proliferation of studies that have examined the impacts of public participation in Citizen Science (CS) that respond to environmental challenges and the recovery of ecosystems, endangered species or other important natural assets. However, comparatively few studies have explored how tourists may play a critical role in the generation of CS data and thus it has been posited that many potential opportunities remain unrealised. By systematically analysing studies that have utilised tourist-generated data in response to environmental challenges or issues, this paper seeks to establish an appraisal of what has so far been established in extant literature and to identify future possibilities for the inclusion of tourists in CS. Via our literature search, a total of 45 peer-reviewed studies were identified via the PRISMA search protocol. Our findings reveal numerous positive outcomes were reported that highlight the significant, yet largely untapped, potential of tourist integration in CS, with studies also offering a range of recommendations on how tourists could be included more effectively to expand scientific knowledge. Notwithstanding, several limitations were observed, and it is critical that future CS projects that utilise tourists for data collection purposes are acutely aware of the challenges they may encounter.
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Affiliation(s)
- Gareth Butler
- College of Humanities, Arts and Social Sciences, Flinders University, Sturt Road, Bedford Park, SA5042, Australia; Faculty of Management, University of Johannesburg, Bunting Road, Cottesloe, Gauteng, 2092, South Africa.
| | - Kirstin Ross
- College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, SA5042, Australia.
| | - Julian Beaman
- College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, SA5042, Australia.
| | - Cassie Hoepner
- College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, SA5042, Australia.
| | - Ryan Baring
- College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, SA5042, Australia.
| | - Karen Burke da Silva
- College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, SA5042, Australia.
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4
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Rambahiniarison J, Agustines A, Alexopoulos K, Araujo G, Armstrong AO, Arnold S, Barruga A, Cañete T, Conales S, Delijero K, Enolva NP, Flam AL, Keane E, Labaja J, Legaspi CG, Murie C, Murray R, Oliver SP, Pierce SJ, Ponzo A, Rohner CA, Schifferer R, Snow S, Spakowski M, Stevens GMW, Tilgel T, Wong JNC, Yaptinchay AA, Barr Y. Distribution of the reef manta ray Mobula alfredi and the oceanic manta ray Mobula birostris in the Philippines: a collaborative effort for conservation. JOURNAL OF FISH BIOLOGY 2023; 102:492-503. [PMID: 36451613 DOI: 10.1111/jfb.15283] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 11/21/2022] [Indexed: 06/17/2023]
Abstract
Little is known about manta ray population size, structure and connectivity in the Philippines. In collaboration with dive operators, non-governmental organizations and authorities, sightings of manta rays were collated into a single national database. Using in-water photographs and videos gathered through citizen science and dedicated research efforts, this study compiled sightings between 2004 and 2020, showing 22 separate sites throughout the archipelago with manta rays present. A total of 392 individual reef manta rays (Mobula alfredi) and 107 oceanic manta rays (Mobula birostris) were identified from the collected footage. Four specific sites in the provinces of Masbate and Palawan together hosted 89% of all identified individuals and accounted for 95% of sightings, highlighting these areas are key aggregation sites. This study also reports the movements of M. birostris within the Philippines, based on photo-identification of three individuals moving 150 km between Cebu and Masbate. Despite the growing number of recreational divers in Daanbantayan and San Jacinto, an 80% decline in M. birostris sightings was observed at these sites. To ensure effective future conservation, it is recommended that efforts focus on the identification and protection of manta ray hotspots and migratory corridors, the creation of a sustainable tourism framework and, most important, the implementation of mitigation strategies to reduce fisheries interactions.
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Affiliation(s)
- Joshua Rambahiniarison
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
- Coastal Oceans Research and Development - Indian Ocean East Africa, Mombasa, Kenya
| | - Ariana Agustines
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | | | - Gonzalo Araujo
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
- Marine Research and Conservation Foundation, Lydeard St Lawrence, Somerset, UK
| | - Asia O Armstrong
- Project Manta, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Shannon Arnold
- The Manta Trust, Catemwood House, Norwood Lane, Dorset, UK
| | - Aldrin Barruga
- Ticao-Burias Pass Protected Seascape, Department of Environment and Natural Resources V, Provincial Environment and Natural Resources Office, Masbate City, Philippines
| | - Titus Cañete
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | - Segundo Conales
- Tubbataha Management Office, Puerto Princesa City, Philippines
| | - Kymry Delijero
- World Wildlife Fund Philippines, Puerto Princesa City, Philippines
| | - Nonie P Enolva
- Bureau of Fisheries and Aquatic Resources - Region 5, Department of Agriculture, Camarines Sur, Philippines
| | - Anna L Flam
- Marine Megafauna Foundation, West Palm Beach, Florida, USA
| | - Eliya Keane
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | - Jessica Labaja
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | | | - Calum Murie
- The Department of Biological Sciences, University of Chester, Chester, UK
- The Underwater Africa Foundation, Inhambane, Mozambique
| | - Ryan Murray
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | - Simon P Oliver
- The Department of Biological Sciences, University of Chester, Chester, UK
| | - Simon J Pierce
- Marine Megafauna Foundation, West Palm Beach, Florida, USA
| | - Alessandro Ponzo
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | | | | | - Sally Snow
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | - Martina Spakowski
- Large Marine Vertebrates Research Institute Philippines, Bohol, Philippines
| | | | | | | | | | - Yotam Barr
- School of Zoology, Tel Aviv University, Tel Aviv, Israel
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5
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Azevedo OM, Correia AM, Micarelli P, Reinero FR, Rijllo G, Giglio G, Sperone E. Sex Differences in the Individual Behaviour of Bait-Attracted White Sharks ( Carcharodon carcharias, Linnaeus, 1758) Are Linked to Different Environmental Factors in South Africa. BIOLOGY 2022; 11:biology11121735. [PMID: 36552245 PMCID: PMC9774687 DOI: 10.3390/biology11121735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 12/05/2022]
Abstract
The white shark (Carcharodon carcharias) is a charismatic species and, consequently, one of the most studied and protected sharks. This species can be found in a wide range of temperatures and depths, showing site fidelity and migrating across the oceans. This offers a challenge to understanding the processes influencing their lifecycle and, more importantly, assessing anthropogenic disturbances to their populations. These predators' behaviour has been linked to diverse abiotic factors. Here, an ethological approach was used to understand the influence of environmental variables on white shark behaviour. A different environmental impact was found between the activity of females and males toward the bait. Females performed a higher number of behaviours under daylight, lower sea surface temperatures, short wavelets, clear and cloudy skies, under La Niña events, elevated moonlight and high tides. Males behaved with more complexity at dawn, medium sea surface temperatures, large wavelets, few clouds, high tides, and elevated moonlight. The world's aquatic habitats are experiencing significant physiochemical shifts due to human-induced climate change. Knowledge about how white sharks respond to environmental factors is essential to guide management and conservation actions.
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Affiliation(s)
- Olga Mouteira Azevedo
- Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, 87036 Rende, Italy
- Correspondence: (O.M.A.); (E.S.)
| | - Ana Mafalda Correia
- Coastal Biodiversity Laboratory, Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), 4450-208 Matosinhos, Portugal
- Department of Biology, Faculty of Sciences, University of Porto (FCUP), 4169-007 Porto, Portugal
| | - Primo Micarelli
- The Sharks Studies Centre—Scientific Institute, 58024 Massa Marittima, Italy
| | | | - Giuseppe Rijllo
- Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, 87036 Rende, Italy
| | - Gianni Giglio
- Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, 87036 Rende, Italy
| | - Emilio Sperone
- Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, 87036 Rende, Italy
- Correspondence: (O.M.A.); (E.S.)
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6
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Carpenter M, Cullain N, Venables SK, Tibiriçá Y, Griffiths C, Marshall AD. Evidence of Závora Bay as a critical site for reef manta rays, Mobula alfredi, in southern Mozambique. JOURNAL OF FISH BIOLOGY 2022; 101:628-639. [PMID: 35691006 PMCID: PMC9544570 DOI: 10.1111/jfb.15132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
The largest known reef manta ray (Mobula alfredi) population in Africa has been monitored for more than 20 years at several locations on the coast of the Inhambane Province in southern Mozambique. Nonetheless, before this study, little had been reported on the population dynamics of M. alfredi from Závora, a remote bay in the region. Photographic mark-recapture was used to investigate the size and structure of M. alfredi that aggregate at "Red Sands," a reef cleaning station in Závora Bay. An 11 year photographic data set was used to identify 583 M. alfredi individuals between 2010 and 2021. More than half of M. alfredi individuals were resighted at least once, with most encounters (up to 18 for one individual) occurring during the peak sighting period in July-November each year. An even sex ratio was observed, 44% females and 50% males, with no significant difference in resightings between the sexes. Pollock's robust design population models were used to estimate annual abundance, emigration, annual apparent survival and capture probability at Red Sands from July to November over a 6 year period (2016-2021). Abundance estimates varied year to year, ranging from 35 (95% c.i. [30, 45]) up to 233 (95% c.i. [224, 249]) M. alfredi individuals. Given the seasonal affinity of M. alfredi observed at Red Sands, this study highlights the importance of understanding fine-scale site use within the larger home range of this population to develop local management strategies.
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Affiliation(s)
- Michelle Carpenter
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
| | - Nakia Cullain
- Marine Megafauna FoundationWest Palm BeachFloridaUSA
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | | | - Yara Tibiriçá
- Departamento de Biología, Facultad de Ciencias del Mar y AmbientalesUniversidad de CádizCádizSpain
| | - Charles Griffiths
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
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7
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Farmer NA, Garrison LP, Horn C, Miller M, Gowan T, Kenney RD, Vukovich M, Willmott JR, Pate J, Harry Webb D, Mullican TJ, Stewart JD, Bassos-Hull K, Jones C, Adams D, Pelletier NA, Waldron J, Kajiura S. The distribution of manta rays in the western North Atlantic Ocean off the eastern United States. Sci Rep 2022; 12:6544. [PMID: 35449381 PMCID: PMC9023537 DOI: 10.1038/s41598-022-10482-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 01/19/2022] [Indexed: 01/22/2023] Open
Abstract
In 2018, the giant manta ray was listed as threatened under the U.S. Endangered Species Act. We integrated decades of sightings and survey effort data from multiple sources in a comprehensive species distribution modeling (SDM) framework to evaluate the distribution of giant manta rays off the eastern United States, including the Gulf of Mexico. Manta rays were most commonly detected at productive nearshore and shelf-edge upwelling zones at surface thermal frontal boundaries within a temperature range of approximately 20–30 °C. SDMs predicted highest nearshore occurrence off northeastern Florida during April, with the distribution extending northward along the shelf-edge as temperatures warm, leading to higher occurrences north of Cape Hatteras, North Carolina from June to October, and then south of Savannah, Georgia from November to March as temperatures cool. In the Gulf of Mexico, the highest nearshore occurrence was predicted around the Mississippi River delta from April to June and again from October to November. SDM predictions will allow resource managers to more effectively protect manta rays from fisheries bycatch, boat strikes, oil and gas activities, contaminants and pollutants, and other threats.
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Affiliation(s)
- Nicholas A Farmer
- NOAA/National Marine Fisheries Service, Southeast Regional Office, 263 13th Ave S., St. Petersburg, FL, 33701, USA.
| | - Lance P Garrison
- NOAA/National Marine Fisheries Service, Southeast Fisheries Science Center, 75 Virginia Beach Dr., Miami, FL, 33149, USA
| | - Calusa Horn
- NOAA/National Marine Fisheries Service, Southeast Regional Office, 263 13th Ave S., St. Petersburg, FL, 33701, USA
| | - Margaret Miller
- NOAA/National Marine Fisheries Service, Office of Protected Resources, 1315 East-West Highway, Silver Spring, MD, 20910, USA
| | - Timothy Gowan
- Florida Fish and Wildlife Research Institute, 100 8th Ave SE, St. Petersburg, FL, 33701, USA
| | - Robert D Kenney
- Graduate School of Oceanography, University of Rhode Island, Bay Campus Box 40, 215 South Ferry Rd., Narragansett, RI, 02882, USA
| | - Michelle Vukovich
- Normandeau Associates Inc., 4581 NW 6th Street, Suite H, Gainesville, FL, 32609, USA
| | | | - Jessica Pate
- Marine Megafauna Foundation, 7750 Okeechobee Blvd, Ste 4-3038, West Palm Beach, FL, 33411, USA
| | - D Harry Webb
- Georgia Aquarium, 225 Baker St. NW, Atlanta, GA, 30313, USA
| | | | - Joshua D Stewart
- The Manta Trust, Catemwood House, Corscombe, Dorchester, Dorset, DT2 0NT, UK.,NOAA/National Marine Fisheries Service, Southwest Fisheries Science Center, La Jolla Shores Drive, La Jolla, CA, 92037, USA
| | - Kim Bassos-Hull
- Sharks and Rays Conservation Research Program, Mote Marine Laboratory, 1600 Ken Thompson Pkwy, Sarasota, FL, 34236, USA
| | - Christian Jones
- NOAA/National Marine Fisheries Service, Southeast Fisheries Science Center, 3209 Frederic Street, Pascagoula, MS, 39567-4112, USA
| | - Delaney Adams
- Western Washington University, 516 High Street, Bellingham, WA, 98225, USA
| | - Nicole A Pelletier
- The Manta Trust, Catemwood House, Corscombe, Dorchester, Dorset, DT2 0NT, UK
| | - Jordan Waldron
- Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Stephen Kajiura
- Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
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8
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How Big Is That Manta Ray? A Novel and Non-Invasive Method for Measuring Reef Manta Rays Using Small Drones. DRONES 2022. [DOI: 10.3390/drones6030063] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This study explores the application of small, commercially available drones to determine morphometric the measurements and record key demographic parameters of reef manta rays (Mobula alfredi) in Raja Ampat, Indonesia. DJI Mavic 2 Pro drones were used to obtain videos of surface-feeding M. alfredi with a floating, known-length PVC pipe as a reference scale—thus avoiding the need to utilize altitude readings, which are known to be unreliable in small drones, in our photogrammetry approach. Three dimensions (disc length (DL), disc width (DW), and cranial width (CW)) from 86 different individuals were measured. A hierarchical multivariate model was used to estimate the true measurements of these three dimensions and their population-level multivariate distributions. The estimated true measurements of these dimensions were highly accurate and precise, with the measurement of CW more accurate than that of DL and, especially, of DW. Each pairing of these dimensions exhibited strong linear relationships, with estimated correlation coefficients ranging from 0.98–0.99. Given these, our model allows us to accurately calculate DW (as the standard measure of body size for mobulid rays) using the more accurate CW and DL measurements. We estimate that the smallest mature M. alfredi of each sex we measured were 274.8 cm (males, n = 30) and 323.5 cm DW (females, n = 8). We conclude that small drones are useful for providing an accurate “snapshot” of the size distribution of surface-feeding M. alfredi aggregations and for determining the sex and maturity of larger individuals, all with minimal impact on this vulnerable species.
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9
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Fernando D, Stewart JD. High bycatch rates of manta and devil rays in the "small-scale" artisanal fisheries of Sri Lanka. PeerJ 2021; 9:e11994. [PMID: 34589295 PMCID: PMC8434810 DOI: 10.7717/peerj.11994] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/27/2021] [Indexed: 01/05/2023] Open
Abstract
Background Expanding fisheries in developing nations like Sri Lanka have a significant impact on threatened marine species such as elasmobranchs. Manta and devil (mobulid) rays have some of the most conservative life history strategies of any elasmobranch, and even low to moderate levels of bycatch from gillnet fisheries may lead to significant population declines. A lack of information on life history, demographics, population trends, and fisheries impacts hinders effective management measures for these species. Method We report on mobulid fishery landings over nine years between 2011 and 2020 across 38 landing sites in Sri Lanka. We collected data on catch numbers, body sizes, sex, and maturity status for five mobulid species. We used a Bayesian state-space model to estimate monthly country-wide catch rates and total annual landings of mobulid rays. We used catch curve analyses to estimate total mortality for Mobula mobular, and evaluated trends in recorded body sizes across the study period for M. mobular, M. birostris, M. tarapacana and M. thurstoni. Results We find that catch rates have declined an order of magnitude for all species across the study period, and that total annual captures of mobulid rays by the Sri Lankan artisanal fishing fleet exceed the estimated annual captures of mobulids in all global, industrial purse seine fisheries combined. Catch curve analyses suggest that M. mobular is being fished at rates far above the species' intrinsic population growth rate, and the average sizes of all mobulids in the fishery except for M. birostris are declining. Collectively, these findings suggest overfishing of mobulid ray populations in the northern Indian Ocean by Sri Lankan artisanal fisheries. We recommend strengthening the management of these species through improved implementation of CITES, CMS, and regional fisheries management actions. In addition, we report on the demographic characteristics of mobulids landed in Sri Lanka and provide the first record of M. eregoodoo in the country.
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Affiliation(s)
- Daniel Fernando
- Blue Resources Trust, Colombo, Sri Lanka.,The Manta Trust, Dorchester, United Kingdom.,Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
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10
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Osgood GJ, White ER, Baum JK. Effects of climate-change-driven gradual and acute temperature changes on shark and ray species. J Anim Ecol 2021; 90:2547-2559. [PMID: 34145907 DOI: 10.1111/1365-2656.13560] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 04/07/2021] [Indexed: 11/29/2022]
Abstract
Climate change is altering distributions and abundances of marine species through both gradual and acute changes in temperature and productivity. Due to their high mobility and metabolic rates, elasmobranchs (sharks and rays) are likely to redistribute across latitudes and depths as they thermoregulate, but little is known about their responses to these climatic changes, which could vary widely across this diverse group of species. Here, we assessed how species with differing mobility and ecology responded to gradual changes in daily sea surface temperature (SST) and acute temperature anomalies, caused by the El Niño-Southern Oscillation (ENSO), at Cocos Island, Costa Rica, the site of multiple marine heatwaves. We used generalized linear mixed models to analyse 34,342 records of relative abundance or frequency of occurrence for seven shark and ray species collected in 27 years (1993-2019) by a dive company. We compared effect sizes for SST and the Oceanic Niño Index across the different species, which vary widely in body size and mobility. Large, mobile species responded strongly but inconsistently to temperature. For scalloped hammerhead sharks Sphyrna lewini, a 1℃ rise in SST reduced counts by over 14%, and dropped the occurrence of their large schools by almost one-fifth (19.4%). Mobula ray occurrence also declined substantially with a few degrees rise in SST, whereas tiger shark Galeocerdo cuvier occurrence sharply increased. These species also had divergent responses to the ENSO: S. lewini and G. cuvier were sighted with greater frequency during La Niña events, and their abundance dropped considerably during El Niño events-over a twofold decline between a strong La Niña and strong El Niño for S. lewini. In contrast, Mobula rays showed little response to ENSO. The smaller and sedentary Triaenodon obesus exhibited the weakest response of all species to both SST and the ENSO, reflecting its lower metabolic rates and mobility. Climate change will continue to impact elasmobranchs, even for smaller and more localized species, with the potential to impact the effectiveness of marine protected areas (MPAs). Our results compel further work on the diversity of elasmobranch responses to environmental change.
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Affiliation(s)
| | - Easton R White
- Department of Biological Sciences, University of New Hampshire, Durham, NH, USA.,Gund Institute for Environment, University of Vermont, Burlington, VT, USA
| | - Julia K Baum
- Department of Biology, University of Victoria, Victoria, BC, Canada
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Venables SK, Marshall AD, Germanov ES, Perryman RJY, Tapilatu RF, Hendrawan IG, Flam AL, van Keulen M, Tomkins JL, Kennington WJ. It's not all black and white: investigating colour polymorphism in manta rays across Indo-Pacific populations. Proc Biol Sci 2019; 286:20191879. [PMID: 31594509 PMCID: PMC6790782 DOI: 10.1098/rspb.2019.1879] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 09/18/2019] [Indexed: 11/12/2022] Open
Abstract
Intraspecific colour polymorphisms have been the focus of numerous studies, yet processes affecting melanism in the marine environment remain poorly understood. Arguably, the most prominent example of melanism in marine species occurs in manta rays (Mobula birostris and Mobula alfredi). Here, we use long-term photo identification catalogues to document the frequency variation of melanism across Indo-Pacific manta ray populations and test for evidence of selection by predation acting on colour morph variants. We use mark-recapture modelling to compare survivorship of typical and melanistic colour morphs in three M. alfredi populations and assess the relationship between frequency variation and geographical distance. While there were large differences in melanism frequencies among populations of both species (0-40.70%), apparent survival estimates revealed no difference in survivorship between colour morphs. We found a significant association between phenotypic and geographical distance in M. birostris, but not in M. alfredi. Our results suggest that melanism is not under selection by predation in the tested M. alfredi populations, and that frequency differences across populations of both species are a consequence of neutral genetic processes. As genetic colour polymorphisms are often subjected to complex selection mechanisms, our findings only begin to elucidate the underlying evolutionary processes responsible for the maintenance and frequency variation of melanism in manta ray populations.
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Affiliation(s)
- Stephanie K. Venables
- Centre for Evolutionary Biology, School of Biological Sciences, the University of Western Australia, Crawley, Western Australia, Australia
- Marine Megafauna Foundation, Truckee, CA, USA
| | | | - Elitza S. Germanov
- Marine Megafauna Foundation, Truckee, CA, USA
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Robert J. Y. Perryman
- Marine Megafauna Foundation, Truckee, CA, USA
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ricardo F. Tapilatu
- Research Center for Pacific Marine Resources, Universitas Papua, Manokwari, Papua Barat, Indonesia
| | - I Gede Hendrawan
- Department of Marine Sciences, Faculty of Marine Sciences and Fisheries, Udayana University, Bali, Indonesia
| | | | - Mike van Keulen
- Environmental and Conservation Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Joseph L. Tomkins
- Centre for Evolutionary Biology, School of Biological Sciences, the University of Western Australia, Crawley, Western Australia, Australia
| | - W. Jason Kennington
- Centre for Evolutionary Biology, School of Biological Sciences, the University of Western Australia, Crawley, Western Australia, Australia
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