New study reveals key areas for shark and ray conservation in the Maldives
A new study published in Frontiers in Marine Science reveals that sanctuary status alone is not enough to ensure that all essential areas for sharks and rays are identified and integrated into conservation strategies.
The research, led by Rui Rosa, professor at CIÊNCIAS Lisboa and researcher at MARE | ARNET, together with his team, Margarida Vizeu-Pinheiro, Sebastião Farias, and Maria Lourie, analysed seven years of data collected at Lhaviyani Atoll, in the Maldives, one of the world's richest archipelagos for marine megafauna.
With data from across more than 12,700 dives at 94 sampling sites between 2017 and 2024, the team recorded approximately 143,000 observations of sharks and rays. In total, 25 species were identified, of which 23 are listed as threatened on the IUCN Red List. Four are Critically Endangered: the great hammerhead shark (Sphyrna mokarran), the giant guitarfish (Rhynchobatus djiddensis), the bowmouth guitarfish (Rhina ancylostoma), and the ornate eagle ray (Aetomylaeus vespertilio).
The study identified four hotspots along the northern edge of the atoll, two of which were already integrated within the internationally recognised Important Shark and Ray Areas (ISRAs). The other two fall outside these boundaries, despite recording some of the highest occurrences of Critically Endangered species in the entire study, raising serious concerns about the adequacy of current protection boundaries.
The researchers also found a clear link with the monsoon cycle: the abundance and diversity of sharks and rays peak at the end of the southwest monsoon, between August and September, when currents favour productivity and prey concentration. During the transition to the northeast monsoon, between December and March, numbers decline.
Despite sharing the same ocean, sharks and rays do not occupy the same spaces. Sharks favour areas of greater geomorphological complexity, such as exposed reef slopes and strong-current channels. Rays are more frequent in lagoons and sheltered areas, often associated with cleaning stations, where small fish remove parasites from larger species.
For sharks, dissolved oxygen and chlorophyll are also key drivers of abundance. Rays are influenced by temperature, oxygen, and current velocity.
Elasmobranchs are key players in marine ecosystems, exerting top-down control over food chains as apex predators. But their value extends beyond ecology. In the Maldives, shark-watching tourism generated 2.3 million dollars in a single year, with a single grey reef shark valued at up to 35,000 dollars annually at the most popular dive sites. By 2010, shark-based ecotourism accounted for 30% of the national GDP, prompting a nationwide ban on shark fishing that same year.
However, in November 2025, the Maldives reversed that decision, reopening fishing for the gulper shark (Centrophorus granulosus) after 15 years of protection. In response, the researchers advocate for expanding marine protected areas, strengthening fisheries regulation, integrating hotspots into marine spatial planning, and maintaining continuous monitoring of these populations through citizen science.
Researcher Rui Rosa leaves a clear warning: "Even the world's largest sanctuaries are not immune to the effects of human activity. Protecting sharks and rays means protecting the future of our oceans."
Read the full paper here.