Common threats to sea turtles in Australia and the Pacific

Human-caused threats

Habitat loss

Coastal development in Australia and the Pacific is increasingly destroying nesting beaches and forcing females to find new, and potentially less safe, locations to lay their eggs. Coastal activities such as dredging and runoff pollution from agriculture is damaging sea grass beds where turtles forage. 

Bycatch

Sea turtles are often accidentally caught and drown in discarded and active commercial and recreational fishing gear like crab pots, fishing line, gill nets/ghost nets, trawls, and longlines.

Beach nets

State governments and local councils are using netting on major beaches to protect against shark attacks. Migrating turtles, alongside many other marine species, are often caught up in these nets and subsequently drown if not freed in time.

Pollution

Plastic debris, e.g. balloons and plastic bags, in the water looks like food to sea turtles and is often ingested causing significant health issues or death. Similarly, their health is being impacted by the effect of toxic runoff and oil spills that contaminate the water and food chain leading to death and instability of food resources and habitats.

Poaching and illegal trade

Sea turtles and their eggs are being hunted for meat, for their carapaces, and other by-products.

Climate change

Rising sand temperatures are skewing sex ratios with warmer temperatures producing more females which will impact breeding success rates over time. The rise in sea-level causes coastal erosion and inundates nesting beaches impacting the safety of nests and causing the death of turtles prior to hatching. 

Vessel strikes

Turtles are being hit and injured or killed by boats and ships. The damage is caused by the bottom of the vessel or the propeller leaving a deep gash, often in the turtle’s carapace. Vessel strikes are often fatal, however, if the turtle can be saved, the rehabilitation timeframe is often many months to years.

Light pollution

Lights from coastal development are disorienting to nesting females, deterring them from nesting, and instead causing them to return to the water. Hatchlings automatically head towards light which is often the moon’s reflection over the ocean. Artificial lights on beach promenades or coastal developments such as hotels and apartments, disorient the hatchlings leading them away from the sea and towards danger, e.g. roads and footpaths.

Natural threats

Predation: Sea turtles have natural predators throughout their entire lifespan.

Eggs: Sea turtle eggs have predators including feral animals such as dogs/dingos, pigs, goannas, crabs, and rats.

Hatchlings: From the moment hatchlings come out of the nest, hatchlings are targeted by birds, feral dogs, crabs, baby sharks, and large fish.

Juvenile/Adults: As sea turtles increase in size, they have fewer predators, however, they can be preyed upon by sharks and killer whales while in the ocean and are commonly preyed upon by crocodiles, feral dogs, and feral pigs whilst onshore for nesting.

Disease/Illness: Sea turtles can face many natural diseases, e.g. fibropapillomatosis, and illnesses caused by fungi, and also parasites, such as blood flukes and roundworms.

Fibropapillomatosis is a disease affecting sea turtles characterised by the growth of benign, often debilitating, tumors on their skin, eyes, and internal organs. It is caused by the chelonid herpes virus 5 (ChHV-5) and is most common in green sea turtles although it affects all species. Large tumors can interfere with a turtle’s ability to swim, feed, and see, often leading to death. Currently there is no complete cure for fibropapillomatosis except for removal and management of accessible growths.