In South Florida, researcher Christina Coppenrath took this photo while freediving with a small manta ray.
Photograph by BETHANY AUGLIERE
On Juno Beach, Florida, Jessica Pate drives an all-terrain vehicle back and forth across the beach, searching for traces of endangered sea turtles, when she notices a huge black shadow moving in shallow water.
When I looked closer, it turned out to be a manta ray. A biologist and avid diver, Pate has seen people swimming with these big fish in Indonesia or Hawaii — but never in the busy coastal waters of southern Florida, where there are more than 6 million people.
The 2010 encounter piqued Paate's interest, and she began searching for scientific literature on the number of manta rays in South Florida, but found only one 1998 paper. So she set out to change that.
Over a period of more than three years, from 2016 to 2019, Pate surveyed these elegant swimmers in South Florida waters and finally identified 59 individuals, which the researchers called "urban manta rays."
"We've seen manta rays swim in front of President Trump's Mar-a-Lago estate and Jimmy Buffett's Margaritaville Resort," Pate said. In addition, high-rise condominium residents in Miami reported seeing several manta rays swimming in the sea at home during the outbreak.
A manta ray swims through the bay, which is frequented by boats.
Photo by BRYANT TURFFS, COURTESY MARINE MEGAFAUNA FOUNDATION
A manta ray wanders away from the resort of Margaritaville. Most of the manta rays studied were photographed in water about 2.75 meters deep.
摄影：JESSICA PATE, COURTESY MARINE MEGAFAUNA FOUNDATION
In addition to their cosmopolitan lifestyle, Florida manta rays are almost always juveniles because females have no mating scars on their bodies and males have small genitalia.
In a new study published this week in the journal Endangered Species Survey, Pate and colleagues provide strong evidence that there is a manta ray nursery in South Florida — the third to be found to date. Manta rays tend to have a rich diet and are relatively free of predators, which is conducive to the safe growth of their cubs.
The manta ray, named Stevie Nicks, crossed under a patch of seaweed as it cruised along the southern Florida coastline.
Paate, founder and chief scientist of the Florida Manta Ray Project, said: "This is an unexpected discovery, and two other nurseries in Indonesia and the Gulf of Mexico were also discovered in 2018 and 2019."
"We know very little about manta rays," she added, such as where they give birth, how long they live, and how they choose their spouses. As a result, the newly discovered nursery could reveal more about this little-known creature and let us know how to protect them.
According to the International Union for Conservation of Nature, two species of manta rays in the genus Anterior manta rays, the double-snouted manta ray (up to 9 meters wide) and the Acetohus manta ray, are easily extinct. In 2018, the United States listed the double-snouted manta ray as endangered under the Endangered Species Act.
Pate added that genetic evidence is provided in a forthcoming paper suggesting that the Florida manta rays belong to a third species, a new species of manta ray.
"Right under our noses"
To study, Pate borrowed his grandfather's fishing boat and spent a long time searching the shallow water between Jupiter Island and Boynton Beach. As the boat moved slowly forward, Pate stood on the bow of the boat, looking for the huge black figure moving on the white sand beach.
"It's no exaggeration to say that I've identified every manta ray-shaped rock in South Florida," she quipped. Later, she also incorporated aerial photographs of drones and small planes into her survey data.
Over the years, several of these 59 manta rays have been frequented in Patte's eyes, including one that she and her colleagues named Stevie Nicks, and a manta ray called Gillie, which appears 23 times.
Pate said the unusually high number of manta ray juveniles recurs in the same place, indicating the presence of nurseries. It's also possible that the warm, shallow waters of South Florida help these critters regulate their body temperature, so they grow faster.
"When studying manta rays, areas where juvenile manta rays are found are rarely seen. It's very rare to see juvenile fish in only one area, like we saw in southeast Florida," she said.
Still, manta rays excel at long-distance travel, so the only way to confirm the existence of nurseries in South Florida is to install satellite and acoustic labels on young manta rays, and Pate has begun working with the National Oceanic and Atmospheric Administration (NOAA). (No one has ever seen manta rays give birth in the wild, and their breeding habits remain largely a mystery.) )
"This study confirms that we really don't know much about these animals," adds Csilla Ari, a professor at the University of South Florida who also works at the Manta Ray Pacific Research Foundation. "They're right under our noses, in such a densely populated area, and they've been ignored for so long."
Human conflict
Environmental ecologist and National Geographic explorer Joshua Stewart, who was involved in discovering the potential manta ray nursery in the Gulf of Mexico, was also surprised by how close the possible nursery was to humans.
A manta ray named Ginger had bait glued to it. Nearly half of the manta rays studied were injuries related to the fishing or yachting industry.
Photographed by BETHANY AUGLIERE
"We talk a lot about the human impact on manta rays, and there's really some evidence to prove it where I work," said Stewart, deputy director of the Manta Ray Foundation. "But it's really shocking to see manta rays cruising along Florida's coastal waterways, with huge yachts passing by them."
Many Florida residents have boat licenses, which explains why many of Florida's manta rays bear traces of conflict with humans. According to Patte's study, 27 percent of the manta rays studied had been entangled in fishing lines, and 46 percent had been injured or scarred by boat propellers, fishing equipment or other unexplained causes.
Net-net entanglement and overfishing are major threats to manta rays, with female manta rays not reaching sexual maturity until they are 8 or 10 years old, reproducing slowly, and producing one or two juvenile manta rays every few years.
But once they reach adulthood, manta rays face a much smaller threat because they have grown too big for most predators. So "protecting these young manta rays is very important for the viability of the entire population," Pate said.
Given these weaknesses, Pate hopes her research will eventually prompt the U.S. government to designate an important manta ray habitat in South Florida.
"These manta rays and millions of people live in South Florida, so it's not easy to protect them," Pate said. "But with manta rays dwindling worldwide, this is crucial for the conservation of this species."
(Translator: Strange Flowers Blossom)