Young and vulnerable Jordi Chias/Naturepl.com

Put it down to a combination of inexperience, mistaking plastic for food, or maybe swimming where most plastic waste collects. Whatever the reasons, new evidence shows that young turtles off Australia’s Queensland coast are more at risk than their elders of swallowing plastic waste.

Fresh autopsies on 246 sea turtles that washed up dead on beaches across Queensland showed that 58 had ingested between one and 329 fragments of plastic, which might have contributed to their deaths. The rest died of other causes, such as boat collisions. But of the 58 plastic consumers, only four were full or near adults. Most – 41 – were juveniles. Very young “post-hatchlings” seemed particularly at risk: of the 246 dead sea turtles, 24 of them were post-hatchlings – and 13 of them had eaten plastic.

One explanation is that young turtles swim nearer the surface in offshore waters where plastic floats, and drift with plastic-rich prevailing currents.


“It may be that they are less selective than adults and encounter higher concentrations of debris,” says Britta Denise Hardesty of the Commonwealth Scientific and Industrial Research Organisation in Hobart, Australia, and head of the survey. “Plastics, particularly balloons, can resemble jellyfish and squid, as well as crustaceans and sponges,” she says.

From the autopsy data, the team worked out how the risk of a turtle’s death escalated as plastic load in its gut increased. For instance, half of the young turtles about 45 centimetres would be expected to die if they swallowed 17 plastic items. Even swallowing just one piece of plastic raised the risk of death by 22 per cent, the team calculated, with the potential to kill through gut blockage or perforation.

“Turtles can live 80 years or more, but if they eat something that blocks their intestines, even a single piece of plastic, it can be deadly,” says Hardesty. She hopes the results will discourage careless disposal of waste, adding that plastics have been found in hundreds of marine species, including fish eaten by humans.

Journal reference: Scientific Reports, DOI: 10.1038/s41598-018-30038-z