Mystery surrounds the origin of turtle hatchlings that shocked the island last summer.

Described by some as Bermuda’s “natural history event of the century”, almost 90 green turtles hatched last August at Builder’s Bay — the first recorded turtle hatching on the island for more than 90 years.

Despite genetic testing of several hatchlings who died before reaching the water, the origin of the turtle remains unknown.

Some believed that the hatchlings were the delayed result of the Operation Green Turtle transplant operation between 1968 and 1978, in which turtle eggs were brought to the island from Costa Rica by David Wingate.

Conservationists had hoped the turtles would return to Bermuda to nest when mature. Female turtles reach sexual maturity between the age of 25 and 35, but a turtle laying eggs for the first time at the age of 40 is not impossible.

Meanwhile, a second theory was that the female turtle could have come from the Florida population, which has boomed in recent years as the state has increased its own conservation efforts

However, according to a recent article in Hakai Magazine, genetic tests have found that there is a less than ten per cent chance the turtles descended from either Floridian or Costa Rican stocks.

Ann Meylan, a Florida-based sea turtle biologist who was on the island at the time of the hatching, working with the Bermuda Turtle Project, told the magazine that she collected tissue from three dead hatchlings, sending the samples to a genetics expert at the University of Georgia.

Dr Meylan suggested to the magazine that the turtles might have migrated from Mexico, which also saw an increase in turtle hatchings last year, but added: “The female turtle’s origin will have to remain a mystery for the time being.”

Green turtles were once very common in Bermuda, but use of the turtles for food and the increase of pests like rats severely diminished their numbers.

The hatchlings were first discovered by a member of the public, who noticed one turtle attempting to cross the road near the beach. He took the animal to the Bermuda Aquarium Museum and Zoo, and a search of the area revealed almost a dozen of the animals struggling in long grass.

Researchers later found a total of 87 eggs buried in the beach, the majority of which appeared to have successfully hatched.