Climate affects our marine wildlife.
Climate affects our marine wildlife. Contributed

Why efforts to save our turtles 'may not be enough'

A JAMES Cook University marine scientist has praised action taken between the Bundaberg Regional Council and the State Government to protect loggerhead turtles, saying that it was about time that local governments worked to protect the endangered species.

"Time may tell, it may not be enough," said Townsville based Associate Professor Mark Hamann.

He was referring to efforts to reduce light pollution, as well as the State Government's decision to restrict developments at Bargara to five and six storeys.

According to the Department of Environment and Science, there were 382 Loggerhead turtles (Caretta caretta) nesting on the Woongarra Coast in the summer, with the more significant rookery being Mon Repos.

The hatchling turtles were vulnerable to lighting, but they were also at risk due to climate change because of their sensitivity to temperatures, Dr Hamann said.

When eggs were exposed to warmer temperatures they would likely be born female, but if the temperatures were too high then the eggs would not hatch.

Although storey heights and lighting were not proven to impact temperatures for turtles, developments did have an impact because it increased accessibility to people and frightened the turtles away, or it attracted the hatchlings inland and disorientated them.

Dr Hamann understood that there had been 100 per cent rates of females being born at Mon Repos.

The high rate of females that hatch at Mon Repos is not a new trend, according to the Department of Environment and Science.

A departmental spokeswoman said that mainland beaches, such as Mon Repos, were generally warmer and mostly produced female hatchlings.

"This has been the situation since the commencement of these types of studies in the late 1970s," she said.

"It is the combined hatchling production from the mainland and the Barrier Reef islands that is the important issue, not just hatchling production for an individual beach."

According to a 2013 report by turtle expert Col Limpus, there were six index nesting beaches for monitoring loggerhead turtles in eastern Queensland, with the major nesting population being Mon Repos.

In this report he said there were an estimated 3500 female turtles across these six beaches in the summer of 1976-77.

But by 1999-2000 there was a sharp drop to an estimated 500 females.

The drop had been credited to turtles drowning when captured on prawn trawls.

The maximum temperature for Mon Repos and Heron Island were below 34 degrees which was the lethal limit for turtle eggs, according to data collected in the 1980s.

The minimum temperature that turtle eggs could be exposed to was 24 degrees. The hatching success published in the 1980s was 91 per cent.