June 19 (UPI) -- Researchers have discovered the world's first known manta ray nursery. Scientists found the nursery in the Flower Garden Banks National Marine Sanctuary located off the coast of Texas in the Gulf of Mexico.
The nursery of juvenile mantra rays was first observed by Joshua Stewart, a marine biology PhD student at Scripps Institution of Oceanography at the University of California, San Diego.
"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," Stewart said in a news release. "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."
Stewart is the executive director of Manta Trust, a conservation program dedicated to protecting manta rays around the globe.
"This discovery is a major advancement in our understanding of the species and the importance of different habitats throughout their lives," he said.
Stewart worked with researchers at Scripps and NOAA's Office of National Marine Sanctuaries to document the nursery.
Oceanic manta rays, or giant oceanic manta rays, Mobula birostris, are found in tropical and subtropical waters. They typically congregate in areas far from the coast, making them difficult to find and study. The plankton-eating rays live in the open ocean. Adults can grow wingspans of up to 23 feet.
Most of scientific literature on manta rays concerns adults. Until now, little was known about juveniles.
After initially spotting the juveniles, scientists regularly monitored the marine reserve, documenting the rays behavior. They found 95 percent of the rays visiting the Flower Garden Banks were juveniles. The young rays had an average wingspan of just over seven feet.
Because each ray has a unique pattern of spots on their underside, divers were able to keep track of the different rays visiting the reserve's banks.
Scientists described their observation of the manta nursery in the journal Marine Biology.
In the near future, researchers hope to begin tagging and tracking the juvenile rays as they travel to and from the banks. Biologists believe the nursery's proximity to deep, cold water, where plankton are abundant, may explain the rays' presence. The young mantas can seek refuge among the warm, shallow water near the banks after foraging.
Scientists say the discovery is a reminder of the importance of marine reserves for vulnerable marine species. Earlier this year, giant manta rays were declared "threatened" under the U.S. Endangered Species Act.
"Nowhere else in the world has a manta ray nursery area been recognized -- which heightens the importance of the sanctuary for these pelagic species," said George P. Schmahl, superintendent of Flower Garden Banks National Marine Sanctuary. "The discovery of the sanctuary as a nursery area for the species raises many more questions, some of which we can hopefully start studying with Josh Stewart and other partners."