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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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WIN a Beuchat Air Light Bag!!!

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For this week’s competition, we’ve teamed up with our good friends at Beuchat to give away an Air Light Bag!

The Air Light Bag from Beuchat is a practical travel bag that takes up minimum storage space.

  • Material: 600 denier and 1,000 denier nylon/PVC
  • Soft roller bag, easily stored in its mesh bag
  • Internal retaining straps
  • Zip fastener with eyelets for padlocks
  • Side compartment for fins
  • Outer document pocket with coated zip and carry strap
  • Backpack style straps concealed behind the foam back-plate
  • Drainage vents
  • Red over-moulded wheels; detachable wheel block

To be in with a chance of winning this awesome prize, all you have to do is answer the following question:

In a recent post on Scubaverse.com (which you can read here), we reported that the Philippines have been recognised as the World’s Leading Dive Destination at the 27th World Travel Awards. In the article it states how many islands make up the Philippines… how many are there?

Is there:

  • A) 7,209
  • B) 7,532
  • C) 7,641

Answer, A, B or C to the question above:

Beuchat Air Light Bag December 2020

Competition
  • Enter the country you live in
  • Terms and Conditions: This competition is open to all visitors to www.scubaverse.com except for members of the Scubaverse team and their families, or employees of Beuchat and their families. A valid answer to the competition’s question must be entered. If no valid answer to the competition’s question is entered, your entry will be invalid. Only one competition entry per entrant permitted (multiple entries will lead to disqualification). Only one prize per winner. All prizes are non-transferable, and no cash alternative will be offered. In the event that the prize cannot be supplied, no liability will be attached to www.scubaverse.com. When prizes are supplied by third parties, www.scubaverse.com is acting as their agents and as such we exclude all liability for loss or damage you may suffer as a result of this competition. This competition closes on 13/01/21. The winner will be notified by email. The Editor-in-Chief’s decision is final.

  • The following fields are optional, however if you fill them in it will help us to determine what prizes to source in the future.

  • Date Format: MM slash DD slash YYYY
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Gear News

Quick Scuba Tips #1: How To Prep A New Mask for Scuba Diving (Watch Video)

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How To Prep A New Mask for Scuba Diving. Can’t I just take my new mask diving straight out of the box? Well, actually, no. It needs a little work to make it dive ready.

In this, the first in our new scuba diving quick hints and tips series, I’m going to show you how to prepare a new mask for scuba diving with three quick techniques, all aimed at stopping your scuba mask from fogging.

Yes, this link is an affiliate link. Purchases made through these links may earn me a small commission at no extra charge to you.

Dive safe, dive often!

James


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