The Great Barrier Reef authority will analyse data on green turtle nesting numbers to look for signs the population is bouncing back almost three years after Cyclone Yasi. 

Great Barrier Reef Marine Park Authority species conservation manager Mark Read said data on the number of female green turtles that nest will provide valuable information on the health of this vulnerable species.

The cyclone and related extensive flooding destroyed the Great Barrier Reef's seagrass supplies, the major food source for the herbivorous green turtle species.

November and December mark the peak period in the Great Barrier Reef where female turtles lay their eggs on a beach in the region where they were born.

“The number of females able to breed also tends to plummet when there’s a decline in seagrass or algae.

“Usually there’s a time lag of about two to three years after a severe weather event before the proportion of nesting females bounces back, so this year’s nesting season will be important in showing whether numbers are returning to normal levels.”

A range of government agencies, Traditional Owner groups, researchers and volunteers conduct annual surveys during turtle nesting season, with the largest counts taking place on Raine Island, the Capricorn Bunker group of islands near Bundaberg and Gladstone, and the mainland beaches around central Queensland.

Dr Read said turtles converging on the Marine Park are coming from as far away as Indonesia, Papua New Guinea, New Caledonia, Fiji and Vanuatu.

“The sea journey for a large number of turtles will take many weeks, and some will even end up doing a 5000 kilometre round trip,” Dr Read.

“Interestingly, they don’t stop for food along the way. They store their entire energy reserves as fat which is enough to last them for their trip to the Reef and back home again — all while producing up to 1000 eggs within their bodies.

“It really is an amazing feat.”

Some marine turtle species can nest up to seven times in the one season, with each clutch containing about 120 eggs.

The temperature of the nest during incubation determines the sex of the hatchlings. Warm, dark sand produces mostly females, while eggs laid in cooler, white sand results mostly in males.

To give eggs the best chance of survival, beach users are asked to stay clear of nesting turtles, as well as their eggs or hatchlings.

The use of artificial light should also be limited as it can confuse hatchlings and cause them to lose direction as they attempt to make their way to the ocean.
Local turtle nesting activity can be reported through the Eye on the Reef phone app available at www.gbrmpa.gov.au.

To report sick, injured, stranded or dead turtles please call 1300 ANIMAL (1300 264 625).

Read related story:

• 'Christmas comes early for stranded turtles', November 22, 2013