Researchers have identified several independent stocks of flatback populations in Australia .
Genetic research has shown that (and this is true of other species also) these stocks or populations within the species do not interbreed. What this means is, if one of the stocks is threatened and numbers fall there may be no recovery.
The stocks for the flatback have been identified as:
• The East Australian population, centred in the Southern Barrier Reef with approx. 1000 nesting females annually.
• The Northeastern Gulf of Carpentaria population. Approx 3000 nesting females annually.
• The Southern Gulf of Carpentaria population. Approx. 1000 nesting females annually.
• The Eastern Arnhem Land population. Imprecise count ?1000s nesting females annually.
• The Western Arnhem Land population. Imprecise count possibly 7000 nesting females annually.
• The Northwest Shelf population. Imprecise count possibly in the hundreds nesting females annually.
Looking at the above information it can be seen that the number of nesting flatbacks on mainland beaches in the Mackay district represent approx. 10% of the East Australian population.
Research has shown that incubation temperature determines the sex of the hatchling. At a certain temperature (The pivotal temperature) a nest will produce 50% male and 50% female hatchlings. (not as precise as that) the sex of the hatchlings will be biased one way or the other. In the case of sea turtles the cooler the temperature more males will be produced and the hotter the temperature more females will be produced.
Our records of the past 19/20 years, indicates that the mainland beaches in this area are producing predominately female hatchlings. Preliminary information in regard to the offshore island sites, indicate that at least some of them may be producing predominately male hatchlings. More temperature research on the offshore island sites needs to be completed.