New research has found baby turtles making their first swim out to sea are more likely to become fish food if the nest they emerged from is too near a jetty.
The study took place on Thevenard Island, off the coast of Onslow in north Western Australia, where 61 flatback turtle hatchlings were tracked using small tags the size of Tic Tacs.
It was expected the hatchlings would swim straight out to safer open waters.
"Normally when we have tracked the baby turtles, once they enter the water, they swim very quickly offshore because the near-shore zone is where all the predators are hanging out and wanting to eat them," said co-author Dr Michele Thums from the Australian Institute of Marine Science.
Instead, the tracking devices showed the hatchlings were spending more time near the shoreline at night and spending the day underneath a nearby jetty.
It was then researchers made a surprising discovery — they we no longer tracking hatchlings but the fish that had eaten them.
"It was a turtle inside the stomach of a fish," Dr Thums said.
Predatory fish such as mangrove jack were residing underneath the jetty during the day and ventured out at night to hunt.
"We did expect to have some predation, normally of around ten per cent, but our predation was about seventy per cent," Dr Thums said.
"It is worrying because the turtle hatchlings represent the next generation and they're a really long-lived species.
"They don't return to nest for about 20 years so we're not really sure at this stage how high predation can be before it will affect the next generation."
Dr Thums and University of Western Australia PhD candidate Phillipa Wilson, who led the study, said more research was needed on the impact jetties may have on the animals.
"When any development happens near turtle nesting sites it's important that we pay attention for the types of lighting on the types of infrastructure that are there," Dr Thums said.
"In terms of infrastructure like jetties, we're not sure yet what mitigation might be needed.
"Future research will help us pinpoint that in in a better way than we can right now."
The study was published in scientific journal Biological Conservation.
