Home Science 59 giant oceanic manta rays found in Florida face fight for survival

59 giant oceanic manta rays found in Florida face fight for survival

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Dozens of baby manta rays found swimming in South Florida have led researchers to believe the area is home to a rare nursery for the threatened species. 

Manta nurseries are usually free from predators and have abundant food sources – only two others have ever been found and neither are in Florida.

Researchers believe the creatures are a new species of giant oceanic manta ray and are set to investigate this case. 

However, the urban environment has a number of potential dangers for these creatures including, boat propellers, toxic sewage and beachgoers also threaten their healthy development. 

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Researchers in South Florida have identified 59 individual manta rays, 95 percent of which were juveniles. They believe this points to the area being a nursery for the creatures, which spend most of their adult life out at sea

Researchers in South Florida have identified 59 individual manta rays, 95 percent of which were juveniles. They believe this points to the area being a nursery for the creatures, which spend most of their adult life out at sea 

After a surprise encounter with a young manta in Juno Beach, marine biologist Jessica Pate spent more than three years scouring South Florida for more. 

Scientists have spotted giant manta rays swimming in front of President Trump’s Mar-a-Lago resort and Jimmy Buffett’s Margaritaville, Pate, said founder of the Florida Manta Project.

It’s the first time a nursery has been discovered in such a highly developed urban area. 

‘In many places, manta rays are seen at remote cleaning stations along coral reefs systems or feeding offshore.,’ Pate said in a statement. 

Only two other manta ray nurseries have ever been discovered before, and never in such a highly developed urban area

Only two other manta ray nurseries have ever been discovered before, and never in such a highly developed urban area

‘Here in Florida, we regularly see manta rays swimming in 5 feet of water over the sand in front of multi-million dollar mansions or high rise hotels and apartment blocks … [and]  feed at the mouths of inlets which have heavy boat traffic.’ 

Her team has identified 59 individuals so far, and given them colorful names like Gillie, Ginger and Stevie Nicks.

They believe the rays they’ve encountered are juveniles, based on the lack of mating scars on the females.

In addition, the males have relatively small claspers, or genitalia.

Ocean mantas spend most of their lives out to sea. 

In a report this week in the journal Endangered Species Research, Pate says their repeated presence in southeastern Florida points to the area being a nursery for young mantas.

If correct, it would be only the third such creche ever found.

The others, identified in the past two years, are in Indonesia and the Gulf of Mexico.

A juvenile manta with a fishing lure still embedded. The warm, shallow waters protect rays from predators and offer an ample food supply. But they leave them open to injuries from fishing equipment and boat propellers

A juvenile manta with a fishing lure still embedded. The warm, shallow waters protect rays from predators and offer an ample food supply. But they leave them open to injuries from fishing equipment and boat propellers

‘It was amazing because it was an unexpected finding,’ Pate told National Geographic. 

Little is known about giant oceanic manta rays, which are larger than reef mantas – their fins pan can reach nearly 30 feet – and have a darker dorsal area. 

They were listed as a threatened species in 2018 but, according to Pate’s report, there’s not enough data on their populations in America to identify critical habitats.

Mantas have been threatened by pollution and fishing, though their own biology works against them, too.

Female mantas don’t reach sexual maturity until eight or 10 years old and only give birth to one or two pups every two years or so.

Female mantas don't reach sexual maturity until eight or 10 years old and only give birth to one or two pups every two years or so

Female mantas don’t reach sexual maturity until eight or 10 years old and only give birth to one or two pups every two years or so

Gestation can last up to 13 months, though no manta rays have ever been seen giving birth in the wild.

In addition to scanning the shallow waters between Jupiter Island and Boynton Beach in her grandfather’s fishing boat, Pate deployed drones to take aerial photos of the 30-mile region. 

‘In many areas where manta rays are studied, it is uncommon to see juvenile manta rays,’ she said. It is very rare to see almost exclusively juveniles in one area, as we do in southeast Florida.’ 

The young mantas have been spotted near Mar-a-Lago and Margaritaville. Researchers say they frequently see them swimming in 5 feet of water over the sand in front of multimillion-dollar mansions

The young mantas have been spotted near Mar-a-Lago and Margaritaville. Researchers say they frequently see them swimming in 5 feet of water over the sand in front of multimillion-dollar mansions

Ocean manta spend most of their time out at sea, so their presence so close to shore supports the idea of a nursery. 

In addition to keeping them safe from attack, the warm, shallow water may help pups regulate their body temperature.

Most of the mantas were spotted swimming in less than nine feet of water and Pate believes the ‘urban mantas’ they discovered may actually be a distinct species.

To learn more, she’s begun tagging the juvenile mantas. 

In addition to giving a better understanding of the manta’s reproductive and parenting habits, Pate hopes her research encourages officials to designate the nursery a critical habitat.

More than a quarter of the rays researchers studied had been caught in fishing nets, according to the report, and almost a third bore scars from boat propellers.

One still had a fishing lure stuck to her body. 

The areas where the manta congregate are also popular with tourists, making safeguarding them difficult.

 ‘They face so many threats in this area, intense boat traffic, recreational fishing, raw sewage and toxic algal blooms. The list goes on and on,’ said Marine Megafauna Foundation co-founder Andrea Marshall, who first discovered this potential new species off the waters of Mexico in 2010. 

‘It is tragic to think that the Floridian population, one of their largest we currently know about, is subject to so many anthropogenic pressures.’ 

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