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First study of world’s largest marine stingray reveals long-distance migration

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Scientists use images and videos submitted by tourists to track rare species in Africa

Smalleye stingrays are the largest marine stingrays on record, reaching disc widths of up to 222 cm, and yet almost nothing is known about them. Scientists from the Marine Megafauna Foundation have for the first time used photo IDs to study this elusive animal in southern Mozambique, one of the only locations where it is regularly seen in the wild. Their findings were published in the journal PeerJ.

“We reported the first sightings of smalleye stingray in 2004 and have since been racing against the clock to learn more about their ecology before it is too late”, said Dr Andrea Marshall, co-founder and principal scientist of the Marine Megafauna Foundation. 31 percent of the world’s sharks and rays are threatened with extinction according to the IUCN Red List of Threatened Species ‒ due to lack of scientific effort and information, it has not been possible to evaluable the conservation status of smalleye stingrays to date. “This species of ray is likely in trouble too but we can’t protect what we don’t know much about. Our study is an important first step in understanding more about the animal’s ecology and behaviour“, she added.

These mysterious giants are thought to be patchily distributed across the Indian Ocean and Western Pacific, but southern Mozambique is probably the best location to encounter them on inshore reefs”, Marshall added.

Diver and smalleye stingray (c) Andrea Marshall, Marine Megafauna Foundation

The marine biologists tested whether photographs of the stingrays’ (Megatrygon microps) white dorsal spots could be used to distinguish and track individuals over long periods.

Through local dive centers, we called on tourists to help us collect images of this solitary stingray. Fortunately for us, southern Mozambique and its rich marine life attract many passionate scuba divers, most of which own GoPros or other lightweight cameras and will happily make their images and footage available for research”, said Atlantine Boggio-Pasqua who volunteered with the Tofo-based foundation.

She added: “Their contributions proved immensely valuable, we managed to gather more than 140 photographs suitable for comparison and identification, with some images dating as far back as 2003.

The team was able to visually identify 70 different individuals, including 15 that had been seen on several occasions in the area. The dorsal spot patterns looked unchanged over the years indicating they may be permanent markings like in manta rays.

Boggio-Pasqua said: “Smalleye stingrays may look intimidating at first glance with their large, razor-sharp tail spines, but they’re actually really charismatic and easy to approach. We hope to receive many photo and video contributions from citizen scientists in future. They could tell us more about the species’ habitat preference as well as feeding and cleaning behavior.”

The encountered stingrays were often spotted at cleaning stations where reef bannerfish and other small fish appeared to be removing parasites from the rays’ skin.

The photographic study also provided a glimpse into the migratory behaviour of Megatrygon microps. Some individuals traveled hundreds of kilometers along the coastline, including a near-term pregnant female which traveled from Tofo to the Bazaruto Archipelago and back (200km in a minimum of 102 days and  a total 400km return trip). She returned to Tofo, no longer visibly pregnant, suggesting this individual had pupped during her journey.

This proved to be the longest straight-line distance ever recorded for any species of whiptail stingrays (Dasyatidae family). Unlike other stingrays, smalleye stingrays are rarely seen resting on the seabed and are thought to be semi-pelagic.

Fishermen with smalleye stingray (c) Andrea Marshall, Marine Megafauna Foundation

Smalleye stingrays are likely under threat from increasing fishing pressures. Targeted and incidental catch in coastal gillnets and industrial purse seiners operating offshore are an ongoing issue in Mozambique.

There are so many questions that remain unanswered about this rare species. Where do they live, how fast do they mature and how do they reproduce? Filling these knowledge gaps is crucial to figuring out how to protect them properly in Mozambique and other parts of the Indian Ocean”, concluded Dr Marshall.

Addressing the lack of available data will eventually allow scientists to formally assess the species’ conservation status in the IUCN Red List and inform management practices.

The study by Atlantine Boggio-Pasqua, Anna Flam and Andrea Marshall, titled ‘Spotting the “small eyes”: using photo-ID methodology to study a wild population of smalleye stingrays (Megatrygon microps) in southern Mozambique’ is published in the journal PeerJ on 11 June 2019 and is freely available here.

For more information about the work of the Marine Megafauna Foundation visit their website by clicking here.

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Four opportunities to go pro in 2024 with Dive Friends Bonaire

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Dive Friends teaches the Instructor Development Course (IDC) several times a year to students who are eager to share their passion for diving with the world.

Dive Friends is known for the personal approach throughout the course. Their in-house course director will lead the students through every essential step, mentoring them to achieve their fullest potential as a dive instructor.

Applications for the following IDC start dates are now open:

  • 12 April
  • 5 July,
  • 20 September
  • 29 November

Partnership with Casita Palma

If the student opts for the IDC-Deluxe or IDC-Supreme package, their accommodation will be arranged for them at Casita Palma. This small and quiet resort is within walking distance from Dive Friends Bonaire’s main dive shop location and has everything you need to relax after an intense day of IDC training. Breakfast is included, so the student will always be fuelled and ready for their day.

Contact Dive Friends Bonaire’s Course Director Eddy for more information: coursedirector@divefriendsbonaire.com.

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SOMABAY: Scubaverse Trip Review (Watch Video)

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In a video created exclusively for Scubaverse.com, Jeff Goodman visits SOMABAY in the Egyptian Red Sea to experience the diving on offer there.

Book your next Red Sea dive adventure with SOMABAY! For more information, visit www.somabay.com.

Stay at the Breakers Diving & Surfing Lodge when you visit! For more information, visit  www.thebreakers-somabay.com.

Find out more about ORCA Dive Clubs at SOMABAY at www.orca-diveclubs.com/en/soma-bay-en.

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Experience the Red Sea in May with Bella Eriny Liveaboard! As the weather warms up, there’s no better time to dive into the crystal clear waters of the Red Sea. Join us on Bella Eriny, your premier choice for Red Sea liveaboards, this May for an unforgettable underwater adventure. Explore vibrant marine life and stunning coral reefs Enjoy comfortable accommodation in our spacious cabins Savor delicious meals prepared by our onboard chef Benefit from the expertise of our professional dive guides Visit our website for more information and to secure your spot: www.scubatravel.com/BellaEriny or call 01483 411590 More Less

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