Mantas & Stingrays

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.

Giant manta ray. Photo by Scott Bennett
Giant manta ray

How big is it? Drones assisting in manta ray research

A global breakthrough in recording manta ray information has been made by an Auckland University doctoral candidate. In a study entitled “How Big Is That Manta Ray?” published in Drones, Edy Setyawan outlined how a drone camera, with the addition of a PVC pipe in the ocean, can be utilised to accurately measure the world’s largest ray species. “I could see that from the drone there was some size variation, some mantas, they are bigger than the others,” said Setyawan.

A whitespotted eagle ray gliding through the waters
A whitespotted eagle ray gliding through the waters

Where eagle rays spread their wings in US waters

Until recently, the geographic wanderings of the whitespotted eagle ray have always been a mystery.

Now, in a study that took place from 2016 to 2018, a team of researchers have started to unlock some of its movement patterns.

The 54 rays in the study were tagged with acoustic transmitters, along both the Gulf of Mexico and the Atlantic coast of Florida, using collaborative acoustic telemetry networks.

Shark fishing makes pregnant sharks abort

The lead researcher, Kye Adams, a PhD student at the University of Wollongong, said that shark fishermen should be made aware of the danger of inducing abortions in pregnant sharks, rays, or skates. So far, the loss of the young aborted by fished sharks has been ignored by both science and fishermen.

Adams said, "It's quite prevalent across a lot of species and also seems to be not well known by both researchers and recreational fishers. "They don't realise these events are abortions, they think they are witnessing a natural birth."

Spotted eagle rays have been observed in Keys waters, but little is known about where they spend most of their time. (Image above is a unrelated filephoto)

Help keep an eye out for spotted eagle rays

In 2009, Mote Marine Laboratory with the National Aquarium in Baltimore initiated a conservation research program on the life history, reproduction, and population status of the elasmobranch Aetobatus narinari, commonly known as the spotted eagle ray To identify where these rays migrate, Mote has tagged animals with traditional tags and with satellite tags that allow the rays’ movements to be followed as they travel.

We don't know if the rays in the Keys come from Southwest Florida, or perhaps even Mexico or Cuba, and we don't know if rays in the Keys favor particular reefs

—Mote biologist Kim Hull