Global turtle study highlights extinction risk and roadmap to recovery

JUNE 23, 2020

by Western Sydney University

A Western Sydney University researcher has contributed to the first global and comprehensive assessment of the world's turtle and tortoise species. The study found half of all 360 turtle and tortoise species worldwide face imminent extinction, but action undertaken now could reverse the decline and save many species.

Published today in Current Biology, 51 experts with the International Union for Conservation of Nature's (IUCN) Tortoise and Freshwater Turtle Specialist Group, are calling for the end of the trade of wild turtles for food and pets as key to a global conservation strategy.

Hundreds of thousands of turtles and tortoises are collected for the wildlife trade every year. Turtles and tortoises are long-living and slow-growing species, which means they can't reproduce fast enough to replenish populations that are taken from the wild. Three species of turtles and tortoises have gone extinct in the last two centuries, but that number will climb if the trade isn't curbed.

Co-author, Associate Professor Ricky Spencer from the School of Science at Western Sydney University, said Australia is not immune to the impacts of turtle trading, and attacks from invasive predators, road mortality, habitat destruction and drought, are all factors contributing to the decline of Australia's most common turtle species by up to 91 per cent.

"In Australia, we are seeing no signs of turtles in some areas, where we previously recorded them in huge numbers. Foxes are the main persistent source of predation, with growing urbanisation, poor water quality and habitation destruction compounding the issues turtles face," explained Associate Professor Spencer.

"The exotic pet trade and illegal smuggling of wildlife both in and out of Australia is also a contributing factor. It is big business."

The study reinforces the essential roles turtles play in the world's ecosystems. They provide critical services such as energy flow, nutrient recycling, scavenging, soil dynamics and seed dispersal in the terrestrial, freshwater, and marine ecosystems in which they occur.

"The research we are conducting at the Experimental Wetland Facility on the University's Hawkesbury campus shows that without turtles in our rivers, water quality would reach toxic levels during our hot summers. During the recent fish kills in the Murray-Darling River system, turtles were likely instrumental in cleaning up the river," said Associate Professor Spencer.

The researchers recommend captive breeding and head starting programs as ways to help certain species of turtles and tortoises. But to be effective, there must be natural habitat remaining to release the animals into. Species like the Australian western swamp turtle were rescued from near extinction by captive breeding efforts, but it is difficult to breed some species in captivity.

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