Baby Turtles Mysteriously Dying on Australian Island

By Kacey Deamer, Staff Writer | July 7, 2016 07:08am ET

There may be such a thing as too many turtles, according to scientists investigating why so few turtle eggs were hatching on Raine Island, located on the tip of Australiaꞌs Great Barrier Reef.

For more than 1,000 years, green sea turtles have nested on Raine Island, where they dig pits to lay and bury their developing eggs. Yet after a millennia of fruitful nesting seasons, the island has recently had a drop in the rate of successful hatches — now less than 30 percent, even in undisturbed nests.

With protective coral along the broad sandy beaches, and no land-based predators, scientists were stumped as to why an otherwise ideal nesting location would have so few baby turtles hatching from eggs and scuttling down to the water.

Seawater was the first suspect. Scientists thought flooding of the nests during high tides was killing newly laid eggs, which cannot survive underwater. Sand was added to a section of the beach in 2014, raising it by 3 to 5 feet (1 to 1.5 meters), but hatching rates were still extremely low. Then in 2015, hatching success doubled, leaving scientists to question what had changed.

A new theory from researcher David Booth of the University of Queensland suggests that the island's popularity for nesting is to blame for the plunge in hatching success.

Fewer turtles laid nests on the island in 2015, Booth said in a statement. That bit of information suggested that "a density-depending effect was limiting hatching rates even in nests that remained undisturbed throughout incubation, rather than the environmental conditions."

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