Bertarelli-Annual-Report-2024-LR - Flipbook - Page 23
Projects
Mobulid Conservation in
the Chagos Archipelago
Lead Investigator: Dr. Joanna Harris,
University of Plymouth
Another expansion for 2023, this project uses data from
satellite tracking, acoustic telemetry, photographic
identification and confiscated catches from illegal fishing
to build a picture of manta rays (Mobula alfredi) and devil
rays (Mobula mobular) in the Chagos Archipelago. With ten
mobulid species in existence, all of them threatened, the
Chagos populations could be a stronghold, but much more
needs to be known about the extent of illegal exploitation.
Marine Science 2023
21
recorded by an array of 14 acoustic receivers positioned
across Egmont Atoll. With more than 300,000 detections
over 2.5 years the project team has been able to build a
fascinating picture of the highly resident aggregations of
mantas – spending up to 77% of their time on the shallow
reefs off the atoll. This year, these data were used to
inform the designation of an IUCN Important Shark and
Ray Area (ISRA) for manta rays around Egmont Atoll.
At a broader scale, satellite-enabled tags have revealed
previously unknown areas of foraging for mantas on
submerged banks in the south-west of the archipelago.
These data are valuable for marine spatial planning and can
enable more informed conservation of habitats crucial to
the health of this valuable population.
Using photographic identification of the abdominal spot
pattern of individual mantas the current documented
population size is 315. Of this group, 42 have been fitted
with acoustic transmitter tags and their movements
Reef manta ray, Maldives © Umeed Mistry, Ocean Image Bank
