Project selected for the Mares de México Award
Conservation of the Giant Manta Ray in Revillagigedo
Identification of gestation and parturition areas of the Giant Manta Ray (Mobula birostris)
The project aims to discover key habitats used by pregnant females in the Revillagigedo Archipelago, Banderas Bay, and the Gulf of California. To achieve this, it will use satellite telemetry, underwater ultrasound, and laser photogrammetry.
Led by Dr. Madalena Cabral and supported by Mares de México, the study aims to deploy satellite tags on oceanic manta rays to track their movements, habitat use, and behavior. The data generated will help identify key areas for gestation and parturition and will be critical for informing conservation and management strategies, including protecting these habitats from threats such as bycatch and supporting the creation or adjustment of marine protected areas.
A collaboration between MMF and Mares de México
Your contribution to this project will allow us to continue generating relevant scientific data to create better public policies and protect this species.
Some populations of giant manta rays around the world have declined by as much as 90%.
Classified as endangered (IUCN) and under special protection in Mexico (NOM-059-SEMARNAT-2010)
SOME RELEVANT RESULTS
Initial satellite data confirm giant manta ray migration corridors outside of Revillagigedo Park
Satellite tracking data indicate that giant oceanic manta rays tagged in Revillagigedo National Park undertake extensive movements beyond the park's boundaries, following key migratory corridors that connect the protected area with international waters, the French Exclusive Economic Zone around Clipperton Island, and important Mexican marine regions such as the Gulf of California and coastal areas of the mainland. Upon leaving the safety of the marine protected area (MPA), these rays frequently enter regions characterized by intense fishing activity, significantly increasing their risk of interaction with fisheries and bycatch. The identification of these migratory corridors highlights the urgent need for collaborative, transboundary management measures and conservation strategies to protect these critical routes and effectively safeguard this highly mobile and vulnerable species.
ALL MANTAS EVENTUALLY LEAVE THE PROTECTED NATURAL AREA; RUNNING THE RISK OF BECOMING VICTIMS OF BYCATCH.
TEAM AND COLLABORATORS
Madalena Cabral
Project Leader
Alonso I. Rodríguez
Photographer and documentary filmmaker
Camilo Thompson
Environmental lawyer
Identification of gestation and parturition areas of the Giant Manta Ray (Mobula birostris) in sites of high biodiversity value in the Revillagigedo Archipelago, Pacific Ocean and Gulf of California
General Objective
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Generate scientific data on Mobula birostris.
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Protect reproductive females.
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Identify key areas (breeding, feeding and gestation zones) inside and outside the Revillagigedo National Park (PNR), in focused areas of the Gulf of California and in the Pacific Ocean.
Specific Objectives
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Expand the database on the distribution, behavior, and population dynamics of the giant manta ray
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Using non-invasive, contactless underwater ultrasound to support manta ray conservation
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Identify critical habitats for pregnant females
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Assess areas at risk of incidental capture and human threats
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Generate information for management policies, protected areas, and specific regulations
Introduction
Giant manta rays (Mobula birostris) are among the most iconic and enigmatic species in the oceans, renowned not only for their imposing size but also for their essential role in maintaining the balance of marine ecosystems. Despite their ecological importance, their reproductive biology and the critical habitats they utilize during the most sensitive stages of their life cycle remain poorly understood, especially in the Eastern Pacific. Regions such as the Revillagigedo Archipelago, Banderas Bay, and the Gulf of California, considered global biodiversity hotspots, offer a unique setting for studying these marine giants and understanding the challenges they face from threats such as bycatch and human impact on their environments.
This project aims to fill these knowledge gaps by using non-invasive, contactless underwater ultrasound to support manta ray conservation, together with satellite telemetry and laser photogrammetry, which will allow researchers to identify gestation, nursery, and feeding areas used by pregnant females. With this information, the project seeks not only to advance the scientific understanding of the species but also to generate evidence that will contribute to the design of more effective conservation strategies, strengthening the protection of these vulnerable populations and promoting the sustainable management of Mexico's marine protected areas.
Justification:
Knowledge gaps
There is limited data on:
Breeding areas
Birthing sites
Distribution of pregnant females
Previous studies at sites such as Nusa Penida or Komodo indicate areas of reproductive use, but similar data are lacking for the Eastern Pacific
Threats :
Classified as endangered (IUCN) and under special protection in Mexico (NOM-059-SEMARNAT-2010).
Incidental catch (tuna purse-seine and gillnets)
Low reproductive rate (1 offspring every 4-5 years for this species)
Habitat degradation due to pollution, unregulated tourism, climate change and bycatch.
Ecological and Economic Importance
Keystone species in marine ecosystems:
Regulates zooplankton populations
Ecosystem health indicator
Important for diving tourism, generating significant income in Baja California Sur and Revillagigedo
Conserving it has implications for the blue economy and marine science in Mexico
Legal and Environmental Aspects.
It links principles of environmental law:
Precautionary
Sustainable development
Intergenerational equity
Scientific Methodologies and Techniques
Satellite Telemetry
Deployment of SPOT and miniPAT satellite tags
They are placed using titanium anchors and metal teathers while scuba diving.
MiniPATs store data about:
Location
Temperature
Depth
It allows the study of migratory routes, habitat use, and birthing areas.
Image 1. Tagging or placement of satellite technology for mobility monitoring.
Images 2 and 3. Satellite technology for mobility monitoring.
Underwater Ultrasound (Duo-Scan: Go Oceanic)
Portable, wireless, and waterproof ultrasound device
It allows you to detect:
Reproductive status
Fetal development
Non-invasive technique and no need for sedation
Real-time images on mobile devices
Goal: to perform 50 ultrasound exams
Image 4. Duo-Scan ultrasound equipment: Go Oceanic
Image 5. Data capture by diver and use of Duo-Scan ultrasound equipment: Go Oceanic
Laser Photogrammetry:
Two parallel lasers allow the wingspan of the blankets to be estimated.
Useful for:
Determine sexual maturity (in females 4 m wingspan)
Identifying individuals by unique ventral spot pattern (photo-ID)
Goal: 50 photogrammetric samples
Image 6. 4K audiovisual camera and two laser measurement modules.
Image 7. Measurement model applied to target species.
Image 8. Natural markings that are digitized by laser and yield specific signs to identify each individual.
Study Sites:
Archipiélago de Revillagigedo (PNR)
Islote La Reina
Isla Cerralvo
Bahía de La Ventana
Ensenada de Muertos
Archipiélago Espíritu Santo
Isla San José, El Pardito, Isla San Francisquito
Image 9. Site map of implementation of scientific methods for monitoring Mobula birostris by satellite tagging, photo ID and ultrasound samples.
Expected Results
Identify critical areas for gestation and parturition
Generate data to support:
Expansions of protected areas
Specific fishing regulations
To contribute scientific knowledge about:
Reproductive cycles
Marine connectivity
Population dynamics of the giant manta ray
Reducing anthropogenic threats and strengthening the conservation of this emblematic species
Academic and Dissemination Relevance
Project supported by top-level researchers and international organizations
Generation of scientific publications
Visual outreach material:
Videos
Underwater photographs
Demonstrative laser photogrammetry
