Mantas & Stingrays

pregnant shark
A pregnant reef shark (Ila France Porcher)

pH Threshold Unlocks Reproductive Maturity in Sharks and Rays

For fish and other water-breathing animals like sharks and rays, reaching reproductive maturity is a crucial milestone that impacts their entire life history. The size at which they reach maturity, coupled with their subsequent growth rate, affects their longevity and reproductive capacity. Now, researchers have pinpointed a specific pH threshold, termed the "reproductive respiration threshold" (RRT), which kickstarts the hormonal processes leading to maturation.

Aellopobatis bavarica: The newly discovered species, complete fossils are only known from Germany. This species is also the largest species of all and can grow up to 170 cm in size.

Scientists Discover 150 Million-Year-Old Species of Rays

In a groundbreaking study led by the University of Vienna, researchers have unearthed evidence suggesting that the seas of the Jurassic era, some 150 million years ago, teemed with a diversity of ray species far beyond what was previously understood. The discovery of a new species, named Aellopobatis bavarica, provides fascinating insights into the evolutionary history of these ancient marine animals.

A quick pass into view.

Enigmatic World of Shark and Ray Behaviour Unveiled

Elasmobranchs have become lucrative targets with the depletion of traditional fish stocks and the surge in the shark fin trade. Although, in recent decades, much scientific evidence has challenged traditional misconceptions, stereotyped media portrayals persist, and they hinder conservation efforts. So, this special issue was created to highlight the complex behaviour and cognition of sharks and rays.

Tiger shark
Tiger shark

Shark and ray populations in Northwestern Atlantic are recovering

The shark and ray population in the north Atlantic are in recovery, according to a recent study published in the Proceedings of the National Academy of Sciences (PNAS) journal.

Lead author Nathan Pacoureau, postdoctoral research fellow at Simon Fraser University (SFU), and his team came to this conclusion after analyzing trends in fishing pressure, fisheries management and population status for wide-ranging coastal sharks and rays in the western Atlantic Ocean. 

A manta ray near Isla de la Plata off the coast of Ecuador. Photo courtesy Fundacion Megafauna Marina del Ecuador.
A manta ray near Isla de la Plata off the coast of Ecuador

Largest known manta ray population is thriving off the coast of Ecuador

Although manta rays are readily capable of long-distance movements of hundreds if not thousands of kilometres, most populations appear to be philopatric (tending to return to or remain near a particular site or area—ed.) with few examples of long-distance dispersal.

Oceanic manta rays, the largest ray species, were listed as threatened under the U.S. Endangered Species Act in 2018. In 2019, their threat category increased from vulnerable to endangered on the International Union for the Conservation of Nature’s Red List.

Sorting out the Stingrays

The bluespotted ribbontail ray is easy to distinguish from other small rays with blue spots by its oval shape. This one was found sheltering under a wreck in the Red Sea. Photo by Nigel Marsh.

Gliding slowly over the rocky reef, I was mesmerised, watching all the colourful reef fishes going about their daily activities. I was so entranced that I was startled to look up and find I was on a collision course with a massive stingray. This was the first stingray I had ever seen, and the giant creature terrified me. In the second it took my panicking brain to work out what to do, the stingray suddenly saw me and also got a shock.