UCSD student discovers world’s first known manta ray nursery

SAN DIEGO — A graduate student at the University of California San Diego’s Scripps Institution of Oceanography has discovered the world’s first known manta ray nursery in the Gulf of Mexico.

Joshua Stewart, a marine biology doctorate candidate, saw the juvenile mantas while conducting research at NOAA’s Flower Garden Banks National Marine Sanctuary off the Texas coast. The habitat is the first of its kind to be described in a scientific study, according to a news release from the Scripps Institution of Oceanography.

Little is known about the juvenile life stage of mantas because baby mantas are virtually absent from nearly all manta populations around the world, which makes the discovery is an important one, researchers said.

“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. This discovery is a major advancement in our understanding of the species and the importance of different habitats throughout their lives.”

After Stewart observed multiple small mantas, he checked with the sanctuary staff to see if such sightings were common. Stewart and staff looked through 25 years of dive log and photo identification data collected by divers and determined that about 95 percent of the mantas that visit the sanctuary are juveniles.

The new study, “Important juvenile manta ray habitat at Flower Garden Banks National Marine Sanctuary in the northwestern Gulf of Mexico, was published Friday in the journal Marine Biology.

“This is exciting news for the manta rays in the northwestern Gulf of Mexico,” said George P. Schmahl, superintendent of the sanctuary. “The understanding that the mantas are utilizing the Flower Garden Banks National Marine Sanctuary, and possibly other reefs and banks in the region, as a nursery has increased the value of this habitat for their existence. Nowhere else in the world has a manta ray nursery area been recognized–which heightens the importance of the sanctuary for these pelagic species. 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.”’