Manta and devil ray aggregations: conservation challenges and developments in the field

Frontiers in Marine Science, Journal Year: 2023, Volume and Issue: 10

Published: April 17, 2023

Manta and devil rays (mobulids) are filter feeding elasmobranchs with extreme K-selective life histories found circumglobally from temperate to tropical waters. Their vulnerability fisheries exploitation, bycatch, boat collisions, entanglement unregulated tourism is exacerbated by their aggregative behavior. Studies have identified aggregation sites around the world for all nine mobulid species, these groupings varying a few individuals thousands. However, terminology used define aggregations drivers underpinning them remain unclear, hindering development of effective management conservation strategies. Here, we analyze behavior providing consistent definitions grouping events summarizing existing research on environmental factors triggering events. We find that behaviors facilitate socializing key history functions in mobulids, including feeding, courtship mating, predation avoidance, cleaning, thermoregulation. Conservation threats mitigation opportunities associated include fisheries, tourism, spatial protection, climate change. Finally, highlight knowledge gaps future prioritization developments field identification sites, study size demographics timing aggregations.

Language: Английский

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Preliminary insights into manta ray (Mobula alfredi and M. birostris) population demographics and distribution in South Africa

Environmental Biology of Fishes, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 8, 2025

Abstract Both the reef manta ray, Mobula alfredi and oceanic ray M. birostris , are repeatedly observed in South Africa, yet little is known about distributions of either species. In this study, we collated citizen science observations since 2003 to reveal six areas KwaZulu-Natal (KZN) Eastern Cape provinces, where rays have been sighted across multiple years. Using their unique ventral spot patterning, 184 individuals were photo-identified, comprising 139 45 . Most photo-identified encountered iSimangaliso Wetland Park (IWP) KZN (89%; n = 119) for Aliwal Shoal (48%; 22). We identified 32 new transboundary records 28 also photographed Inhambane Province, Mozambique, demonstrating connectivity, specifically Závora ( 27). One individual traveled times between IWP Závora, totaling 1305 km, another from Pondoland MPA a distance over 600 km. Further, extend southern range Africa by 500 km Mdumbi Beach Port Ngqura, Cape. These collective findings represent Africa’s first in-water assessment aggregations, showing particular be critical habitat movements documented here suggest population one most mobile globally. hope baseline data provided will drive increased research management along coastlines.

Language: Английский

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Occurrence of mobulid rays in Northwest Madagascar

Environmental Biology of Fishes, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 5, 2025

Language: Английский

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Potential nursery area for the endangered oceanic manta ray in the Gulf of California, México

Environmental Biology of Fishes, Journal Year: 2025, Volume and Issue: unknown

Published: April 22, 2025

Language: Английский

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Insights into the visitations of oceanic manta rays at cleaning stations on coral reefs in the Bird's Head Seascape, eastern Indonesia

Frontiers in Fish Science, Journal Year: 2024, Volume and Issue: 2

Published: Aug. 16, 2024

The globally endangered oceanic manta ray Mobula birostris is believed to spend significantly more time in the open ocean than coastal areas. Nonetheless, Bird's Head Seascape (BHS) eastern Indonesia hosts a large population of this species (over 850 individuals), frequently sighted at coral reef cleaning stations and forming vital asset for marine tourism region. Despite this, detailed understanding movements habitat use wide-ranging within shallow (< 30 m) ecosystems remains limited. Addressing knowledge gap urgently required sustainable management ray-focused Here, we report results an initial passive acoustic telemetry study investigating by rays. Forty-one rays were acoustically tracked from February 2016 August 2019 array 28 receivers deployed known hypothesized transit points across BHS (including regions Raja Ampat, Fakfak, Kaimana). A total 5,822 detections recorded 16 all tagged individuals, 421 visitation events documented 37 out 41 providing valuable insights into their patterns stations. Tagged individuals detected receiver durations ranging 0.2 427.0 min (mean ± SD = 48 64 min). Notably, 94% during daylight hours (reaching peak noon), underscoring apparent diurnal pattern spent around frequent short-range between adjacent (5–12 km apart), with two-thirds 191 occurring neighboring southern Ampat. repeatedly three which previously only hosting rays, suggesting likely also utilize these Our provides important visitations local stations, will inform effective conservation efforts BHS.

Language: Английский

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Occupancy of acoustically tagged oceanic manta rays, Mobula birostris, in Bahia de Banderas, Mexico

Marine Biology, Journal Year: 2023, Volume and Issue: 170(10)

Published: Sept. 1, 2023

Abstract The oceanic manta ray ( Mobula birostris ) is an endangered species commonly seen at islands and seamounts; however, seasonal aggregations have been described in highly productive, coastal areas. Oceanic rays are found high numbers seasonally Bahía de Banderas, Mexico, a unique nearshore aggregation site for the species. We used acoustic telemetry to examine influence of environmental variables on occurrence 66 tagged over seven-year period from 2015 2021. Seasonal trends showed peak detections January March, another May early October. were present when temperature ranged between 25 °C 29 °C, southward wind speeds 3 5 m s –1 , westward speed 2.5 4.5 . Furthermore, rays’ presence was higher low tides Chlorophyll-a values 7 mg m3-1. Results also suggest that El Niño Southern Oscillation (ENSO) had strong effect bay, which consistent with previous studies. south greater morning hours, suggesting during night they may move deeper waters, similar other reported studies devil rays. Our model suggested tag retention time 300 days. This study serves as baseline future management plans minimize impacts this population human activities occurring close proximity sites.

Language: Английский

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Comparative population genomics of manta rays has global implications for management

Molecular Ecology, Journal Year: 2023, Volume and Issue: unknown

Published: Nov. 23, 2023

Understanding population connectivity and genetic diversity is of fundamental importance to conservation. However, in globally threatened marine megafauna, challenges remain due their elusive nature wide-ranging distributions. As overexploitation continues threaten biodiversity across the globe, such knowledge gaps compromise both suitability effectiveness management actions. Here, we use a comparative framework investigate differentiation manta rays, one most iconic yet vulnerable groups elasmobranchs on planet. Despite recent divergence, show how oceanic rays (Mobula birostris) display significantly higher heterozygosity than reef alfredi) that M. birostris populations worldwide. Through inferring modes colonization, reveal contemporary historical forces have likely influenced these patterns, with important implications for management. Our findings highlight potential fisheries disrupt dynamics at local global scales therefore direct relevance international conservation species.

Language: Английский

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Characteristics, residency and site fidelity of photo-identified reef manta rays (Mobula alfredi) population in New Caledonia

Marine Biology, Journal Year: 2024, Volume and Issue: 171(8)

Published: June 28, 2024

Language: Английский

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Novel use of deep neural networks on photographic identification of epaulette sharks (Hemiscyllium ocellatum) across life stages

Journal of Fish Biology, Journal Year: 2024, Volume and Issue: unknown

Published: Aug. 10, 2024

Photographic identification (photo ID) is an established method that used to count animals and track individuals' movements. This performs well with some species of elasmobranchs (i.e., sharks, skates, rays) where individuals have distinctive skin patterns. However, the unique patterns for ID must be stable through time allow re-identification in future sampling events. More recently, artificial intelligence (AI) models substantially decreased labor-intensive process matching photos extensive photo libraries increased reliability ID. Here, AI are first identify epaulette sharks (Hemiscyllium ocellatum) at different life stages approximately 2 years. An model was developed assess compare human-classified juvenile neonate sharks. The also tested persistence adult Results indicate immature unreliable pattern identification, using both human approaches, due plasticity these subadult growth forms. Mature maintain their can identified by 86% accuracy. approach outlined this study has potential validating stability time; however, testing on wild populations long-term datasets needed. study's novel deep neural network development strategy offers a streamlined accessible framework generating reliable from small data set, without requiring high-performance computing. Since many studies commence limited resources, presents practical solutions such constraints. Overall, address challenges associated sets application shark identification.

Language: Английский

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Comparative population genomics of manta rays has global implications for management

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: June 21, 2023

Abstract Understanding population connectivity and genetic diversity is of fundamental importance to conservation. However, in globally threatened marine megafauna, challenges remain due their elusive nature wide-ranging distributions. As overexploitation continues threaten biodiversity across the globe, such knowledge gaps compromise both suitability effectiveness management actions. Here, we use a comparative framework investigate differentiation manta rays, one most iconic yet vulnerable groups elasmobranchs on planet. Despite recent divergence, show how oceanic rays ( Mobula birostris ) display significantly higher heterozygosity than reef alfredi that M. populations worldwide. Through inferring modes colonisation, reveal contemporary historical forces have likely influenced these patterns, with important implications for management. Our findings highlight potential fisheries disrupt dynamics at local global scales therefore direct relevance international conservation species.

Language: Английский

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