Current methods and best practice recommendations for skate and ray (Batoidea) research: capture, handling, anaesthesia, euthanasia, and tag attachment

Reviews in Fish Biology and Fisheries, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 28, 2025

Language: Английский

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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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Closing the air gap: the use of drones for studying wildlife ecophysiology

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 17, 2025

ABSTRACT Techniques for non‐invasive sampling of ecophysiological data in wild animals have been developed response to challenges associated with studying captive or using invasive methods. Of these, drones, also known as Unoccupied Aerial Vehicles (UAVs), and their sensors, emerged a promising tool the ecophysiology toolkit. In this review, we synthesise research scoping review on use drones wildlife PRISMA‐SCr checklist identify where efforts focused knowledge gaps remain. We these results explore current best practices provide recommendations future use. 136 studies published since 2010, aided animal body condition morphometrics, kinematics biomechanics, bioenergetics, health (e.g. microbiomes, endocrinology, disease) both aquatic terrestrial environments. Focal taxa are biased towards marine mammals, particularly cetaceans. While conducted globally, is primarily led by institutions based North America, Oceania, Europe. The obtain morphometric through standard colour sensors single camera photogrammetry predominates. such video tracking thermal imaging allowed insights into other aspects ecophysiology, when combined external techniques biologgers. most used commercially available multirotor platforms modification collect samples, integration techniques, multidisciplinary integrate suite remote sensing methods more fully. outline how technological advances will play key role delivery novel improved data. recommend that researchers prepare influx drone‐assisted advancements cross‐institutional collaborations. describe diversify across species environments sources technologies comprehensive results.

Language: Английский

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Staying Close to Home: Horizontal Movements of Satellite-Tracked Reef Manta Rays Mobula alfredi (Krefft, 1868) in the World’s Largest Manta Sanctuary

Fishes, Journal Year: 2025, Volume and Issue: 10(2), P. 66 - 66

Published: Feb. 5, 2025

Indonesia is home to significant populations of globally vulnerable reef manta rays (Mobula alfredi) in at least four key regions: Berau, Nusa Penida, Komodo, and Raja Ampat. Despite detailed population studies each these regions, little known about their horizontal movement patterns. Our study used satellite telemetry investigate rays’ habitat use ranges. A total 33 were tagged with SPLASH10F-321A tags across the Berau (n = 5), Penida 8), Komodo 6), Ampat 14), yielding usable data from 25 tags. The tracked for 7 118 days (mean ± SD 50 30) July 2014 2022. results showed localized movements, strong residency near tagging sites, high site fidelity as evidenced by area-restricted search (ARS) behaviors frequent revisitations. Most restricted ranges region, no connectivity between regions. Across individuals, range (95% utilization distributions) varied significantly, ranging 19 48,294 km2 4667 10,354). These findings offer important insights into spatial patterns Indonesia, allowing formulation more effective management strategies.

Language: Английский

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Residency and Use of an Important Nursery Habitat, Raja Ampat’s Wayag Lagoon, by Juvenile Reef Manta Rays (Mobula alfredi)

Frontiers in Marine Science, Journal Year: 2022, Volume and Issue: 9

Published: May 26, 2022

The behaviour and spatial use patterns of juvenile manta rays within their critical nursery habitats remain largely undocumented. Here, we report on the horizontal movements residency reef ( Mobula alfredi ) at a recently discovered site in Wayag lagoon, Raja Ampat, Indonesia. Using multi-disciplinary approach, provide further corroborative evidence that lagoon serves as an important M. nursery. A total 34 were photo-identified from 47 sightings sheltered between 2013–2021. Five (14.7%) these individuals resighted for least 486 days (~1.3 years), including two juveniles after 641 649 (~1.7 still using Visually estimated (n=34) disc widths (DW) ranged 150–240 cm (mean ± SD: 199 19), DW measured drones 218 219 cm. tracked GPS-enabled satellite transmitters 12–69 37 22) 2015 2017, nine passive acoustic 69–439 182 109) May 2019–September 2021. Satellite-tracked exhibited restricted lagoon. minimum core activity space (50% Utilisation Distribution-UD) five 1.1–181.8 km 2 extent (95% UD) 5.3–1,195.4 area. All acoustically tagged displayed high area, with no detections recorded outside broader Ampat region. These detected by receivers throughout 24 h diel cycle, more night different day night. observed long-term provides compelling is area this globally vulnerable species. findings have been used to underpin formulation management strategies specifically protect which will be instrumental survival recovery populations

Language: Английский

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First Documented Courtship Behavior between Mobula birostris and M. alfredi at a Coral Reef Cleaning Station in Misool, Raja Ampat

Diversity, Journal Year: 2024, Volume and Issue: 16(6), P. 319 - 319

Published: May 27, 2024

Though a previous study in Sudan confirmed the existence of living hybrid an oceanic manta ray (Mobula birostris) and reef (M. alfredi), courtship behaviors between two closely related species have never been documented. Here we report first observation male M. birostris female alfredi at cleaning station on shallow coral seamount Misool, Raja Ampat, Indonesia. The observed event lasted for approximately 45 min involved one actively chasing mature around repeatedly bumping her left wing tip with his right cephalic lobe, while second continuously flanked to seemingly prevent retreat from potential evasion pursuing male. Notably, exhibited rapid coloration change, likely indicative courtship-related stress, transitioning striking pale hue she throughout activity normal chevron pattern once males departed.

Language: Английский

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Automated body length and body condition measurements of whales from drone videos for rapid assessment of population health

Marine Mammal Science, Journal Year: 2024, Volume and Issue: 40(4)

Published: May 10, 2024

Abstract Monitoring body length and condition of individuals helps determine overall population health assess adaptation to environmental changes. Aerial photogrammetry from drone‐based videos is a valuable method for obtaining measurements cetaceans. However, the laborious manual processing select frames measure animals ultimately delays assessment hinders conservation actions. Here, we apply deep learning methods expedite improve efficiency important morphological whales. We develop two user‐friendly models automatically (1) detect output containing whales (“DeteX”) (2) extract input (“XtraX”). use gray compare versus automated ( n = 86). Our results show reduced times by one‐ninth, while achieving similar accuracy as (mean coefficient variation <5%). also demonstrate how these are adaptable other species identify remaining challenges help further in future. Importantly, tools greatly speed up key data maintaining accuracy, which critical effectively monitoring health.

Language: Английский

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The Effects of Depth and Altitude on Image-Based Shark Size Measurements Using UAV Surveillance

Drones, Journal Year: 2024, Volume and Issue: 8(10), P. 547 - 547

Published: Oct. 2, 2024

Drones are an ecological tool used increasingly in shark research over the past decade. Due to their high-resolution camera and GPS systems, they have been estimate sizes of animals using drone-based photogrammetry. Previous studies drone altitude measure target size accuracy objects at surface; however, depth its interaction with not studied. We DJI Mavic 3 video (3960 × 2160 pixel) images (5280 3960 autonomous underwater vehicle known traveling six progressively deeper depths assess how sizing from a 10 m 80 is affected. Drone altitudes below 40 2 led underestimation 76%. provide evidence that accounting for drone’s can significantly increase 5% or less. Methods described this study be free-swimming, submerged rivals hand-measuring methods.

Language: Английский

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Using Drones with Thermal Imaging to Estimate Population Counts of European Hare (<em>Lepus europaeus</em>) in Denmark

Published: Oct. 20, 2022

Drones equipped with thermal cameras have recently become readily available, broadening the possibilities for monitoring wildlife. The European hare (Lepus europaeus) is a nocturnal mammal that closely monitored in Denmark due to populations declining since mid-1900s. limitations of current population assessment methods, such as spotlight counts and hunting game statistics, could be overcome by relying on drone surveys imaging counts. aim this study was investigate use DJI Mavic 2 Enterprise Advanced tool Danish population. Multiple test flights were conducted over agricultural areas spring 2022, testing various flight altitudes, camera settings, recording methods. used suggest method identifying counting hare. applied methodology then evaluated through case survey had an area 242 ha. Hare detected at altitudes up 80 m it possible fly low 40 without observing direct behavior changes. Thermal images taken these also provided enough detail differentiate between species animal body size proved good indicator. confirmed based identify conduct counts, thus, indicating suggested viable alternative traditional

Language: Английский

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Allometric Growth of the Enigmatic Deep-Sea Megamouth Shark Megachasma pelagios Taylor, Compagno, and Struhsaker, 1983 (Lamniformes, Megachasmidae)

Fishes, Journal Year: 2023, Volume and Issue: 8(6), P. 300 - 300

Published: June 3, 2023

Megamouth sharks Megachasma pelagios Taylor, Compagno, and Struhsaker, 1983, are a large-bodied, planktivorous, deep-sea species with peculiar morphology. Since their initial description in the late 20th century, many individuals of different sizes have been reported, but few studies examined ontogenetic changes body shapes. Here, we assess growth heads fins based on length measurements from nine different-sized (177–544 cm total length). Bivariate analyses showed that head becomes larger relative to increasing size (i.e., positive allometry), whereas caudal fin remains constant isometric growth). This trend differs basking apparently resembles whale some baleen whales, although they all large-bodied filter feeders. Given mouth is linked feeding modes, our results suggest megamouth modes ram-feeding may similarity suction-feeding engulfment-feeding whales.

Language: Английский

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