Flatback sea turtle

The hatchlings begin to leave the nests during the beginning of December, and the clutches will continue to hatch until late March.[12] The peak of hatchling emergence can be seen during February.[12] A flatback sea turtle hatchling is larger than other sea turtle hatchlings with its carapace length averaging 60 mm (2.4 in).[6] Its large size helps protect it from some of the predators after hatching, and allows it to also be a stronger swimmers.[6] The hatchlings tend to stay close to shore and lack the pelagic phase of other sea turtles.[6][10] The hatchlings will feed on the macroplankton present in their surface-dwelling environment.

A flatback turtle hatchling on its way to the sea.

A flatback sea turtle is sexually mature anywhere between 7–50 years of age, and an adult female will nest every two to three years.[6][11] Mating occurs while the male and female are out at sea; therefore, the males will never return to shore after they hatch.[11] The flatback nesting sites can only be found along the coast of Australia within the slopes of the dunes.[7] A female will return to the same beach for her subsequent clutches within the same nesting season. She will return for other nesting seasons, as well.[12] Depending on the area of the nesting site, the nesting season can go from November to January or can last the entire year.[7] Females are able to lay up to four times throughout the nesting season, and the intervals between nesting can be 13–18 days.[7] While using her front flippers to dig, the female will clear away the dry sand located at the top.[11] After she clears the sand, the female will create an egg chamber using her back flippers.[11] After she has laid her eggs, she will then cover the nest again using her back flippers, while also tossing sand back with her front flippers.[11]

The number of eggs in a flatback sea turtle's clutch are fewer than other sea turtles.[6] It will have an average of 50 eggs laid each time in a clutch, while other sea turtles may lay up to 100-150 eggs in a clutch.[6][7] The eggs are about 55 mm (2.2 in) long within these clutches.[6] The sex of the flatback turtle hatchling is determined by the temperature of the sand that the egg is in.[10] If the temperature is below 29 °C (84 °F), the hatchling will be a male, and if the temperature is above this 29 °C it will be female.[10]

The flatback sea turtle is an omnivorous species, but predominantly eats a carnivorous diet. It feeds mostly on the prey found within the shallow waters where it swims.[6] It has been found to feed on soft corals, sea cucumbers, shrimp, jellyfish, mollusks, and other invertebrates.[6][7][11] It will also occasionally feed on seagrasses, even though it rarely feeds on vegetation.[6][11]

A fox, which is a terrestrial predator of the flatback sea turtle.

The flatback sea turtle is preyed upon by both terrestrial and aquatic organisms. The terrestrial predators it must face are dingos, invasive red foxes, feral dogs, and feral pigs.[7] The aquatic predators to this turtle are sharks.[6][10] The hatchlings also face predation from crabs, sea birds, and juvenille saltwater crocodiles on their journey to the waters.[10] Once in the water, the hatchlings can be preyed upon by big fish and even sharks.[10] Due to their large size when they are born and their strong swimming skills, the likelihood of capture is lowered.[6]

An example of gillnets, which are a threat to the flatback sea turtle.

On the International Union for the Conservation of Nature or the IUCN's official website the flatback sea turtle is listed as data deficient.[13] However, the flatback sea turtle is listed as vulnerable nationally in Australia.[5] It is the least endangered of all of the sea turtles.[6] Unlike other sea turtles, there is not a big human demand for the meat of the flatback sea turtle.[6] It does not swim far from shore; thus, it does not get caught in nets as often as other sea turtles.[6] These reasons can contribute to why it is not in more danger of extinction.

All marine turtles are faced with threats such as habitat loss, the wildlife trade, collection of eggs, collection of meat, by-catch, pollution, and climate change.[7] The flatback sea turtle is specifically threatened by the direct harvest of eggs and meat by the indigenous people of Australia for traditional hunting.[9][10] These people are given the right to harvest by the government, but only if for non-commercial purposes.[10] Another threat is the destruction of nesting beaches due to coastal development and the destruction of feeding sites at coral reefs and the shallow areas near the shore.[9] Camping on these beaches compacts the sand and contributes to dune erosion,[10] and the wheel ruts caused by vehicles driving on the beaches can trap the hatchlings on their journey to the sea.[10] Coastal development contributes to barriers that make it difficult or impossible for adult turtles to reach nesting and feeding sites.[10] The flatback sea turtle also falls prey to incidental capture. It is caught by fishermen, particularly by trawling, gillnet fishing, ghost nets, and crab pots.[10] Lastly, pollution is a concern for this creature.[9] Pollution can affect the timing of egg laying, how it chooses its nesting site, how hatchlings find the sea after emerging, and how adult turtles find the beaches.[10]

Historically climate change was thought to be an influential factor affecting the success of flatback sea turtle development, however, through recent research, performed on a select group of turtles, this was found to be untrue. Researchers have studied whether increased nest temperatures would be detrimental to embryos, whether through embryo death or negatively adapted phenotypes.[14] However, the increased nest temperature did not reduce the success of the hatchlings, the hatchling body size, but it did accelerate the development of the embryo.[14] It was also discovered that there was a high 'pivotal sex-determining temperature' in the specific flatback population, which shows that some populations may had adapted to maintain large number of hatchlings of both sexes even under the effects of climate change.[14]

In 2003, a recovery plan was set in place nationally to help this species along with other sea turtles. This plan aims to reduce mortality rates through actions within commercial fisheries and to maintain a sustainable harvest by Indigenous people. Monitoring programs are being developed and integrated, along with managing factors that affect the reproductive success of this species. In Kakadu National Park, a monitoring program has already been set up for this species. This species' critical habitat is being identified for protection. There are also efforts to enhance the spread of information about the flatback sea turtle as well as cooperation and actions internationally.[5]

There is an important turtle rookery on Avoid Island, in the Flat Isles of the Northumberland Islands group, which is a nature refuge owned by the Queensland Trust for Nature since 2006. There has been a monitoring program in place since 2013, and researchers use the facilities to collect data for various projects about the species.[15][16][17]