The large devil skate casts a large shadow as it glides majestically through the water like a spaceship. The species has a “wingspan” of over six meters and catches nutritious crustaceans and plankton in its filtering gap on its underwater journey. Off the coast of Ecuador, a research team has just estimated the number of manta rays (Mobula birostris), also known as “black manta rays”, to be more than 22,0000. The discovery has been published in the scientific journal Marine Ecology Progress. If it’s difficult to take in how large a grouping of 22,000 manta rays is, then you’ll get some help here: The number is ten times higher than in other areas, where the fascinating sea creature otherwise takes its daily swims. – It is clear that there is something new going on here, says Joshua Stewart, associate professor in marine biology, who, together with a handful of ocean-savvy colleagues, is behind the discovery. – This is a rare story, which gives rise to maritime optimism. We typically estimate groupings (of manta rays, editor’s note) at between 1000 and 2000, which makes the species very vulnerable. In this area, we have found more than 22,000, which has not happened before, says Joshua Stewart to Oregon State University’s website. Manta rays can be identified and counted because each one has a pattern of black spots on their bellies that can be compared to the unique fingerprints of humans. Doing unusually well In 2019, the big manta rays made it onto the World Conservation Union’s red list of threatened species, largely because of the threat from commercial fishing. The researchers will now try to find out why the manta rays – which are otherwise extremely vulnerable to human influence on the marine environment (including rising sea temperatures) – are doing so well in Ecuador’s waters. The researchers consider that it is the availability of food that attracts the rays to Ecuador. In addition, the region has cold and nutrient-rich water that rises to the surface, a process called “groundwater upwelling”. – This productive upwelling of groundwater enables the region to house a large number of very large animals, says Joshua Stewart. In addition to a nutrient-rich marine environment, it has been illegal to fish for manta rays in Ecuador since 2010. The same has been the case since 2016 in neighboring Peru. But the rays still face threats from fishing in everyday life. The large rays can become entangled in fishing lines, bump into boats or end their days as bycatch. That’s why it’s important to keep an eye on the number of manta rays off Ecuador’s coast, as climate change and other human activity can make the animal more endangered than it already is, explains Joshua Stewart.
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Ecuador: The Manta Ray’s Paradise | The World’s Best News
