The conservation status of the giant (or oceanic) manta ray (Mobula birostris) has been uplisted to Endangered on the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. An endangered listing is reserved for species with grave conservation concerns. The announcement serves to confirm what we have long suspected – this gentle marine giant is finding it hard to cope with intensifying anthropogenic pressures around the globe. The giant manta ray now joins over 16,000 endangered species to be assessed with this serious threat level. At this stage, 30% of sharks and rays are now threatened with extinction.
The announcement marks the end of a devastating two decades for this species. Targeted for their gill plates – which they use to filter feed on small zooplankton from the water column – the unrelenting and increasing demand for their body parts has fueled both existing and emerging target fisheries. The relatively new Asian-based trade seems to be impacting the giant manta more than other species of manta ray, with the unsustainable harvesting decimating their populations across the globe.
Dr. Andrea Marshall, who lead-authored this newest assessment for the IUCN, has been involved in their assessments since 2003. “The giant manta ray is a classic example of a species that is quickly succumbing to human-induced pressures. When we first assessed manta rays in 2003 there simply was not enough information on the species to determine their conservation status and they were listed as ‘Data Deficient’, but on each of the subsequent assessments, their conservation status increased steadily from Near-Threatened, to Vulnerable and now to Endangered. Their current status is a direct result of unsustainable pressure from fishing, which now threatens to destabilise their populations across the globe.”
To curb the burgeoning trade in their body parts to Asia and to encourage more comprehensive conservation strategies for their populations around the world, the giant manta ray was listed on two of the most important global conservation treaties, the Convention on Migratory Species (CMS) in 2011 and the Convention on the International Trade in Endangered Species (CITES) in 2013.
Sadly, their numbers have continued to decline. “Manta rays simply cannot withstand such pressures on their populations,” Dr. Marshall explains. “They have an extremely conservative reproductive strategy. They reach sexual maturity relatively late in life, they give birth to a single offspring every few years in the wild, they do not look after or defend their young and the offspring themselves are vulnerable when they are small and may not survive. In other words, as a species, they simply cannot reproduce fast enough to build back their numbers once they are depleted.”
This iconic species is not only extremely important from an ecological perspective, giant mantas also provide vast economic benefits to tourism industries around the world. “Interactions with manta rays are highly sought after by dive and snorkel tourists globally and contribute millions of dollars to tourism economies each year, particularly in developing nations. At this pivotal time, recognising their economic value may help to encourage the protection of this enigmatic and now endangered species” explained Dr. Stephanie Venables, a Senior Scientist and manta ray expert at MMF.
The giant manta ray was only formally described (the process of gathering enough scientific evidence to provide a taxonomic description of a newly discovered species) by Dr. Marshall and colleagues in 2009. At the time it was one of the largest species to be described in our oceans and the announcement was met with excitement around the globe. The discovery was covered by the BBC that year in the first-ever documentary on manta rays.
“It is such an honour to have been able to study and describe this species. The realisation that the giant manta ray is now in danger of extinction is a hard pill to swallow”, Dr. Marshall admits. “We are still busy learning about this extraordinary creature and we have only scratched the surface. There is so much more we need to understand, but at this stage, we have put that all aside in favour of protecting the last remaining populations of giant mantas across the globe.”
Header image: Jon Hanson, Flickr, CC BY-SA 2.0, Wikimedia Commons.