Talk about earning your Ph.D.: A Scripps Oceanography graduate student, Joshua Stewart, along with colleagues from NOAA’s Office of National Marine Sanctuaries, recently discovered the world’s first known manta ray nursery off the coast of Texas, somewhat by accident. Publishing a paper on his discovery in Marine Biology on Monday, he and his team have also become the first to ever describe a juvenile manta ray habitat in a scientific study.
Stewart, a marine biology Ph.D. candidate and lead author of the paper, has spent the last seven years studying manta rays. He noticed the juvenile mantas while recently conducting research on manta population structure at Flower Garden Banks National Marine Sanctuary, though he and his colleague Emma Hickerson, a research coordinator at the sanctuary, had at first thought the manta rays were just unusually small.
In a recent interview with Inverse, Hickerson said that she and Stewart didn’t know the region was basically a nursery for young manta rays until they looked more closely and realized their mistake. “[They’re] babies,” Hickerson said. “That was kind of a revelation for us.” Through their research, outlined in the paper, they discovered that the area may be an important nursery habitat for manta rays, specifically for the for Manta birostris and Manta sp. cf. birostris species.
After seeing more small mantas in the area, Stewart worked with marine sanctuary staff to analyze 25 years of dive log and photo identification data collected by divers. Using those photos and observational data, Stewart and sanctuary staff eventually figured out that about 95 percent of the manta rays that visit Flower Garden Banks are juveniles, not just smaller versions of the creatures.
In the study, Stewart and his colleagues explain what makes this a particularly exciting discovery.
While studies of oceanic mantas have increased substantially in the past decade, major knowledge gaps remain in their basic biology, ecology and life history. The juvenile stage in particular is virtually unstudied, as juvenile oceanic mantas are rarely observed in the wild and are known primarily from fisheries and captive individuals.
In the press release, Stewart noted the importance of the nursery discovery when he said:
There’s so much we don’t know about mantas and that’s exciting from a science perspective because it means there are so many questions still waiting to be answered. From a conservation perspective, it means that a lot of the questions that you get to answer will actually be meaningful and have an impact on management.
Oceanic mantas are hard to study, and baby mantas are “virtually absent” from nearly all manta populations worldwide, so scientists don’t know a ton about their juvenile life stage. With this discovery, that may change. Plus, just imagine baby manta rays for a moment. Who wouldn’t want the chance to study those cuties as much as possible?