1. Reef manta rays (Mobula alfredi) are one of the ocean's largest and most charismatic
species. Pressure from targeted and bycatch fisheries coupled with their
conservative life-history traits including slow growth, late maturity, and low
fecundity has led to catastrophic declines of the global population. The species is
now listed as Vulnerable to Extinction on IUCN Red List of Threatened Species.
2. The global M. alfredi population is widely distributed in highly fragmented subpopulations.
The Maldives supports the world's largest known subpopulation that
undergoes seasonal migrations which are thought to be linked to peaks in ocean
productivity induced by the South Asian Monsoon. Although the species is
protected from targeted fisheries in the region, increasing pressures from habitat
degradation and unsustainable tourism activities mean their effective conservation
relies upon knowledge of the species' habitat use, seasonal distribution, and
the environmental influences on such movements.
3. Photo-ID sighting records collected between 2005 and 2017 were used to identify
key aggregation sites throughout the archipelago, and multiple linear regression
and prediction analysis identified the environmental variables affecting
variations in the intra-annual sighting frequency of M. alfredi.
4. Mobula alfredi were recorded at 273 different sites, 48 of which, with >100
sightings at each, were classified as key areas of habitat use. South-west monsoon
winds and chlorophyll-a concentration predominantly affected the monthly percentage
of M. alfredi sighted on the down-current side of the atolls.
5. In a country where climate change and touristic pressure are increasingly threatening
this species and its habitat, the identification of key areas of habitat use and
temporal changes in the use of these sites highlight the areas that should be prioritized
for protection enabling more effective conservation management.info:eu-repo/semantics/publishedVersio
