Flatback Sea Turtle: An Overview
The flatback sea turtle, Natator depressus, is a unique marine reptile with a flattened carapace (shell), unlike other sea turtle species. Its shell is olive-green to grey with pale brown or yellow tones and features large, non-overlapping scales (scutes). Adults measure up to 99 cm (3.25 ft) in carapace length and weigh around 90 kg (198 lbs). Its shell is relatively thin, and its head has a single pair of prefrontal scutes, unlike other sea turtles.
Conservation Status
The International Union for Conservation of Nature (IUCN) Red List categorizes the flatback sea turtle as “Data Deficient.” This indicates insufficient scientific information to assess extinction risk. The international status reflects a lack of recent comprehensive research; a new assessment is underway. Domestically, Australia lists the flatback as “Vulnerable” under its Environment Protection and Biodiversity Conservation Act, indicating a high risk of endangerment without sustained conservation.
Where Flatback Sea Turtles Live
The flatback sea turtle has the most restricted geographic range of all sea turtle species, primarily inhabiting Australia’s continental shelf and shallow coastal waters. They also feed in coastal Papua New Guinea and Indonesia. They prefer turbid, inshore environments like bays, estuaries, and shallow, soft-bottomed seabeds, typically in waters less than 60 m (200 ft) deep. Flatbacks do not undergo an oceanic phase, spending their entire lives in continental shelf waters close to shore, unlike most other sea turtles. All known nesting sites are on sandy beaches across northern Australia.
Major Threats
Flatbacks face numerous threats. Bycatch is a significant concern, as turtles become entangled in fishing gear like trawl nets and gillnets. Habitat degradation also poses a risk from coastal development, pollution (including plastic and oil spills), and loss of nesting and foraging areas. Industrial operations like mining and gas extraction contribute to habitat loss through dredging and port construction; their light pollution can disorient hatchlings.
Climate change presents another challenge, with rising global temperatures affecting hatchling sex ratios and increasing extreme weather events like cyclones that can destroy nests and degrade nesting beaches. Marine debris, particularly abandoned fishing nets, endangers flatbacks through entanglement, leading to hundreds of deaths annually in areas like the Arafura Sea. Historical hunting for meat and eggs contributed to population declines, and natural predators like saltwater crocodiles, dingoes, foxes, and feral pigs still prey on eggs and hatchlings.
Protection and Recovery Efforts
Various initiatives protect flatbacks and support their recovery. Legal protections are in place through Australian national and state legislation, safeguarding the species. Fisheries management strategies aim to reduce bycatch through measures like mandatory Turtle Excluder Devices (TEDs) in trawl fisheries and time and area closures.
Habitat protection efforts include establishing marine protected areas to conserve nesting and foraging grounds, managing coastal development, and controlling pollution. Programs also focus on reducing light pollution near nesting beaches and controlling feral animal populations that prey on eggs and hatchlings. Research and monitoring programs track population trends, nesting success, and migration patterns to inform conservation strategies. Community engagement and education initiatives raise public awareness and encourage responsible practices to aid their survival.