Save our Seas Foundation study pinpoints manta ray hotspot in remote Seychelles area |03 August 2019

Nothing captures the imagination quite like manta rays; the gentle swoop of their pectoral fins move them like magic carpets through tropical seas.

Captivating as they may be, little is known of where, when, or why these mysterious creatures travel around the remote atolls of the western Indian Ocean.

A new study published by researchers from the Save Our Seas Foundation (SOSF) has illustrated the importance of a remote region of the Seychelles for charismatic reef manta rays – a globally vulnerable species.

The study, published on July 4, 2019 in the journal Marine Ecology Progress Series, examined movement patterns of mantas using a form of fish tracking technology called acoustic telemetry.

Over a four-year period, 42 individual mantas were tagged and tracked through an array of 70 bottom moored acoustic receivers in the waters of D’Arros Island and St Joseph Atoll – one of the few places in the country where SOSF researchers had reliable reports of mantas aggregating frequently.

Each time a tagged manta passed through the array, a coded signal was logged detailing the animal’s location.

On average, tagged manta rays were detected at D’Arros and St Joseph 64% of the days they were tracked, demonstrating high levels of residency.

“I find the high residency rates that we reported for tagged mantas at D’Arros and St Joseph to be really interesting, particularly from a conservation point of view,” marvelled SOSF project leader, Lauren Peel of the University of Western Australia. “We aren’t just seeing juvenile mantas in this area. We see juveniles and adults, males and females, and they are all spending a large amount of time at D’Arros Island. Given that Seychelles is such a vast and remote area, the fact that we are seeing these animals aggregating frequently in this place is really important, not only for understanding the drivers of their behaviour, but for conserving this vulnerable species in Seychelles as a whole.”

According to Manta Trust, SOSF long-term partner, a study like this is timely and necessary for the protection of mantas on a larger scale. Currently, manta rays are heavily sought after and unsustainably fished to supply gill plates for use in Asian medicines despite possessing no medicinal qualities and not being a true traditional ingredient.

They also commonly fall victim to by catch (fisheries targeting other species). As a result, manta populations have been devastated globally in recent decades.

“Currently manta rays are protected on an international scale in Seychelles through conventions like CITES and CMS, but on a national and more local scale, they have no formal protection. That’s why this study was so important,” said Guy Stevens, co-founder of Manta Trust. “In better understanding the crucial significance of D’Arros and St Joseph for mantas, our research can help inform future marine protection efforts within the country.”

Aside from mantas, D’Arros and St Joseph have been identified as critical habitat for a plethora of other marine species. The region houses nurseries for black tip and sickle in lemon sharks, and acts as a haven for turtles, seabirds, and numerous species of fish – including the recent SOSF species discovery,

Eviota dalyi.

SOSF hopes this knowledge will resonate in Seychelles at the community level, so that more Seychellois can get involved in promoting marine conservation in the region.

“Mother nature has been extremely generous to this special country of 115 scattered islands,” said Michael Scholl, chief executive of SOSF.

“The high abundance of marine biodiversity is astounding. As a diver myself, I’ve seen first-hand just how awe-inspiring the waters of D’Arros and St Joseph truly are. The Seychellois can feel a great sense of pride for this pristine place and the captivating manta rays that call it home.”

In addition to Peel and Stevens, this study was coauthored by Ryan Daly, Clare Keating Daly, James Lea, Christopher Clarke, Shaun Collin, and Mark Meekan.

Contributed

About Save Our Seas Foundation

Founded in Geneva, Switzerland in 2003, the Save Our Seas Foundation (SOSF) is a philanthropic organisation aimed at protecting and caring for the world’s oceans. Its support for research, conservation and education projects worldwide focuses primarily on endangered species of sharks, rays and skates. Three permanent SOSF research and education centres reinforce its action in Seychelles, South Africa and the USA.

Over the last 15 years, SOSF has supported some 300 projects worldwide, passionately upholding the founder’s plight to protect the population of sharks,

rays and skates, whose presence is essential to the health and biological diversity of our seas.