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The Guanacaste marine area, located
in the northwestern region of Costa Rica, is made up of small islands such as Islas Murciélago (Bat Islands) and Islas Catalinas, both of which are critical habitats for bull sharks and the endangered oceanic manta rays. Guanacaste The Guanacaste marine area, located in the northwestern region of Costa Rica, is made up of small islands such as Islas Murciélago (Bat Islands) and Islas Catalinas, both of which are critical habitats for bull sharks and the endangered oceanic manta rays.
Slide Bull sharks are the only shark species that can live in both saltwater and freshwater Nursey grounds are considered critical habitats for this species, as future generations of reproductive adults depend on the juvenile survival.
Slide Islas Murciélago in the Guanacaste Conservation Area represents a critical habitat for bull sharks, since it is an essential location for their reproductive cycle. Females aggregate in the site where they are selected by males for copulation. Misión Tiburón scientists use acoustic telemetry to study site fidelity and migration patterns of bull sharks in this important area.

Oceanic manta rays visit the Pacific coast of Costa Rica year round, with specific peaks in their numbers being observed in some aggregation sites. Despite being "giant" animals, very little is actually known about this species. At Misión Tiburón, we endeavor to deepen our understanding of this species through further research within the Guanacaste marine area. Pushing for the Conservation of Bull Sharks and Rays Watch our team at
work in Guanacaste
Slide PROJECT Giant Manta PROJECT Bull Shark Andrés López,
founder of Misión Tiburón Studying mobulids at their aggregation sites at cleaning stations and feeding grounds Studying the migration and habitat use by tagging and tracking movements SHARKS Not enough to sustain a healthy ocean. “You don't need to be an expert scientist to understand that if we don't protect juveniles today, we won't have any adults tomorrow”  are there? How many
Slide Bull Shark The aim of this project is to promote the conservation
of bull sharks in Guanacaste, with both local communities and governmental sectors, by studying their population in the Guanacaste Conservation Area and surrounding waters. "Carcharhinus leucas"
Bull sharks are a cosmopolitan tropical and subtropical species commonly found in coastal ecosystems such as estuaries, lagoons and river mouths, thanks to their ability to enter freshwater systems. Similarly to other elasmobranchs, bull sharks use estuaries and river mouths as nurseries. In addition, scientific research has shown that bull sharks also use coastal ecosystems for protection and food during their early stages of life. The permanence of bull sharks in coastal ecosystems makes them a vulnerable species to anthropogenic actions like habitat degradation, pollution, and fishing exploitation. For example, juveniles and adults are occasionally caught by artisanal fishermen. Urban development near these important areas is also considered a substantial threat to bull sharks, due to the fact that this species requires healthy rivers for reproduction, nursing, and protection. The Bull Shark project consisted in tagging bull sharks with acoustic and satellite tags and recording the information with a receiver located on the islet of San Pedrillo, in the Bat Islands archipelago. The data showed a strong fidelity of females to the islands, suggesting a high index of residence for bull sharks at Islas Murciélago; it was also determined that bull sharks prefer to visit the islands during day time rather than at night.
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Slide Educational Activities in Schools Involving Dive Companies Bull sharks currently have a higher economic value as a tourist resource than when targeted in fishing. Local communities benefit directly from SCUBA diving with bull sharks, where divers are able to experience these sharks in a completely natural environment, without the need for baiting. The permanence of bull sharks in coastal ecosystems makes them a vulnerable species to anthropogenic actions like habitat degradation, pollution, and fishing exploitation. During the Bull Shark project, Misión Tiburón carried out educational activities at local schools throughout Guanacaste. We organised several festivals, involving more than 2,000 children. With support from Carlos Hiller, children decorated their school walls with beautiful marine-themed murals. ©David García ©Andres Berrocal The permanence of bull sharks in coastal
ecosystems makes them a vulnerable species to anthropogenic actions like habitat degradation, pollution, and fishing exploitation.
Slide Misión Tiburón scientists regularly carry out studies on oceanic manta rays and devil rays at aggregations sites such as Islas Catalinas and Islas Murcielago. A general lack of research data, compounded by low conservation efforts around the world, including Costa Rica, means that this species is still a mystery to marine scientists. We know some of the places where manta rays congregate, but we have very limited knowledge about their residence, migration patterns and the impact caused by anthropogenic actions. Oceanic Manta Ray Misión Tiburón scientists regularly carry out studies on
oceanic manta rays and devil rays at aggregations sites such as Islas Catalinas and Islas Murcielago. A general lack of research data, compounded by low conservation efforts around the world, including Costa Rica, means that this species is still a mystery to marine scientists. We know some of the places where manta rays congregate, but we have very limited knowledge about their residence, migration patterns and the impact caused by anthropogenic actions. "Mobula birostris"
Rangers ©Andres Berrocal White tip 1 ©Andres Berrocal White tip 3 ©Andres Berrocal White tip 2 Oceanic manta rays and devil rays, known collectively as mobulids, are elasmobranchs (cartilaginous fishes) like sharks. As for the rest of elasmobranchs, mobulids are characterised by slow growth, low reproductive rate and internal fertilization. Because of their biology, they are particularly vulnerable to non-natural mortality. The oceanic manta ray is an endangered species according to the IUCN, and devil rays vary their status from vulnerable to endangered according to the species. The greatest threat to mobulids is, unquestionably, fisheries, both as a target species and as accidental bycatch. Due to fishing, some mobulid populations have declined by more than 80% in recent times. The oceanic manta ray has the largest brain of any fish in comparison to its body weight, and is understood to be a highly social animal, with numerous reports of intra and interspecific interactions. However, there are still many secrets surrounding the life and behaviour of oceanic manta rays. The oceanic manta ray has the largest brain of any fish in comparison to its body weight, and is understood to be a highly social animal, with numerous reports of intra and interspecific interactions. However, there are still many secrets surrounding the life and behaviour of oceanic manta rays. Oceanic manta rays and devil rays, known collectively as mobulids, are elasmobranchs (cartilaginous fishes) like sharks. As for the rest of elasmobranchs, mobulids are characterised by slow growth, low reproductive rate and internal fertilization. Because of their biology, they are particularly vulnerable to non-natural mortality. The oceanic manta ray is an endangered species according to the IUCN, and devil rays vary their status from vulnerable to endangered according to the species. The greatest threat to mobulids is, unquestionably, fisheries, both as a target species and as accidental bycatch. Due to fishing, some mobulid populations have declined by more than 80% in recent times. 
Slide "David Attenborough" The future of
humanity and, indeed,
all life on Earth
depends on us The future of humanity and, indeed, all life on Earth depends on us. "David Attenborough"
Slide The Guanacaste Conservation Area contains important natural habitats for the conservation of biological diversity The Guanacaste Conservation Area
contains important natural habitats for the
conservation of biological diversity The marine habitats of Guanacaste are exposed to seasonal upwelling resulting in significant temperature drops, increased nutrients and lower pH. These unusual oceanographic phenomena have led to the formation of important critical habitats for migratory species, some of them threatened. In particular, the Costa Rica Thermal Dome (CRTD) is a region of high biological productivity off the coast of Guanacaste in the Eastern Tropical Pacific (ETP), which influences the route and movements of migratory species. A Misión Tiburón study carried out in 2018 showed that silky sharks migrate from Isla del Coco National Park to the CRTD. Similarly, the Catalinas Islands are the most important aggregation site in Costa Rica for oceanic giant mantas which visit the area during the upwelling season. These islands form part of the Guanacaste Conservation Area (GCA), which covers 88,000 terrestrial hectares as well as a marine no-take zone of 43,000 marine hectares. The GCA area was declared a UNESCO World Heritage Site in 1999, because of its importance for the conservation of biological diversity on land and at sea; however, such a prestigious designation requires ongoing research, inventories of biodiversity and monitoring of organisms and ecosystems.  Catalinas Islands are the most important aggregation site in Costa Rica for oceanic giant mantas which visit the area during the upwelling season. These islands form part of the Guanacaste Conservation Area (GCA), which covers 88,000 terrestrial hectares as well as a marine no-take zone of 43,000 marine hectares. The GCA area was declared a UNESCO World Heritage Site in 1999, because of its importance for the conservation of biological diversity on land and at sea; however, such a prestigious designation requires ongoing research, inventories of biodiversity and monitoring of organisms and ecosystems.  The marine habitats of Guanacaste are exposed to seasonal upwelling resulting in significant temperature drops, increased nutrients and lower pH. These unusual oceanographic phenomena have led to the formation of important critical habitats for migratory species, some of them threatened. In particular, the Costa Rica Thermal Dome (CRTD) is a region of high biological productivity off the coast of Guanacaste in the Eastern Tropical Pacific (ETP), which influences the route and movements of migratory species. A Misión Tiburón study carried out in 2018 showed that silky sharks migrate from Isla del Coco National Park to the CRTD. Similarly, the
balanced ecosystem ©Charles Pettit balanced ecosystem ©Charles Pettit balanced ecosystem ©Charles Pettit Sanctuary ©Charles Pettit balanced ecosystem ©Charles Pettit balanced ecosystem ©Rolbin Garcia balanced ecosystem ©Rolbin Garcia balanced ecosystem ©Charles Pettit