Endangered species choke on plastic

Green sea turtles are swallowing plastic at twice the rate they did 25 years ago, according to a University of Queensland study.

Researchers from the School of Biological Sciences and CSIRO’s Wealth from Oceans Flagship analysed global research data from the past 25 years and found green and leatherback turtles are eating more plastic than ever before.

The main food that green and leatherback turtles eat is jellyfish. The leatherback, the largest turtle and third largest living reptile, feeds only on jellyfish.

Plastic bags or pieces of plastic floating in the ocean resemble jellyfish.

Because of their anatomy, turtles cannot regurgitate the plastic bags when they mistakenly eat them. The backward facing spines in their throats, which have evolved to help them hold onto jellyfish while they eat them, catch onto plastic bags in a similar way - what goes down stays down.

Study leader and PhD candidate Qamar Schuyler said turtles ate more plastic than any other form of debris.

“Our research revealed that young ocean-going turtles were more likely to eat plastic than their older, coastal-dwelling relatives,” Schuyler said.

The study found that stranded turtles in areas with high concentrations of marine debris did not experience a correspondingly high probability of debris ingestion.

“Amazingly, turtles found adjacent to the heavily populated New York city area showed little or no evidence of debris ingestion, while all of the turtles found near an undeveloped area of southern Brazil had eaten debris,” Schuyler said.

“This means conducting coastal clean-ups is not the single answer to the problem of debris ingestion for local sea turtle populations, although it is an important step in preventing marine debris input into the ocean.

“Results from this global analysis indicate oceanic leatherback turtles and green turtles are at the greatest risk of being killed or harmed from ingested marine debris.

“To reduce this risk, man-made debris must be managed at a global level, from the manufacturers through to the consumers - before debris reaches the ocean.”

An estimated 80% of debris comes from land-based sources, so it is critical to have effective waste management strategies and to engage with industry to create appropriate innovations and controls to assist in decreasing marine debris.

Australia is home to six of the seven species of sea turtle, all of which are endangered.

The findings from the study have been published in the journal Conservation Biology.