Rare Baby Manta Ray Habitat Discovery Could Help Protect Threatened Species

As he drifted through the water in the northwestern Gulf of Mexico, marine biologist Joshua Stewart spotted something few people will ever see in their lives: a young manta ray.

"I was incredibly surprised because I had only seen a juvenile manta once before, and they're very rare in most field studies," said Stewart, a graduate student at the Scripps Institution of Oceanography at the University of California in San Diego, in a statement.

On a dive off the coast of Texas, he stumbled upon a place in the tropical waters that ocean experts now believe is the first ever-documented manta ray nursery that humans have come into contact with. The environment there is teeming with young mantas, newborns through adolescents of the giant oceanic manta species, Manta birostris. Scientists think this significant finding could help them study these gentle giants of the sea more closely than ever before, since mantas typically live out of reach, far from coastal areas, making their populations hard to access.

Observing young mantas has been even more of a challenge since they are rarely observed in the wild, and humans have not had much luck finding where the young mantas congregate during their first days on Earth, according to a statement from the National Marine Sanctuaries.

When he first dove in @fgbnms, Joshua Stewart was shocked to see a juvenile manta ray. What he didn't know is that young mantas are common there.

Now, Stewart & collaborators have shown that the sanctuary is the 1st documented manta nursery in the world: https://t.co/sQ9RVWMM9M pic.twitter.com/e14BO6Iz3V

— Sanctuaries (NOAA) (@sanctuaries) June 20, 2018

"The juvenile life stage for oceanic mantas has been a bit of a black box for us since we're so rarely able to observe them," said Stewart.

"Identifying this area as a nursery highlights its importance for conservation and management, but it also gives us the opportunity to focus on the juveniles and learn about them," he added. "This discovery is a major advancement in our understanding of the species and the importance of different habitats throughout their lives."

Stewart collaborated with colleagues from the National Oceanic and Atmospheric Administration's Office of National Marine Sanctuaries to publish the discovery in the journal Marine Biology in June.

He discovered the juvenile mantas while conducting research on manta population structure at an underwater preserve, Flower Garden Banks National Marine Sanctuary, one of several underwater parks protected by the Office of National Marine Sanctuaries.

Research on the life cycle of oceanic manta rays is more important than ever because they were recently listed as threatened under the Endangered Species Act, which was passed in the 1970s to protect the habitats of threatened and endangered species. Little is known about these rays, including where their critical habitats exist in U.S. waters, making it difficult to determine how best to protect them. Scientists think that knowing the location of a nursery could make a difference in preserving the species.

"This is exciting news for the manta rays in the northwestern Gulf of Mexico," says Emma Hickerson, the Flower Garden Banks National Marine Sanctuary's research coordinator and a co-author of the paper. "Nowhere else in the world has a manta ray nursery area been recognized, which heightens our understanding of just how important the sanctuary is for these iconic species."