Marine turtles - Threats

Under threat before they even hatch

Habitat loss and degradation
Uncontrolled development has led directly to the destruction of critically important marine turtle nesting beaches. Lights from roads and buildings attract hatchlings and disorient them away from the sea. Instead of finding the ocean, the hatchlings fall prey to predators or die the following day from the heat of the sun. Furthermore, vehicle traffic on beaches compacts the sand and makes it impossible for female turtles to dig nests.

Sea walls and jetties change long-shore drift patterns and can cause erosion or destruction of entire beach sections. Beach restoration projects aimed at protecting seaside buildings, through dredging and sand filling continue to destroy important nearshore feeding grounds and alter nesting beaches.

Additionally, important marine turtle feeding habitats such as coral reefs and seagrass beds are continuously being damaged or entirely destroyed as a result of sedimentation, nutrient run-off from the land, insensitive tourist development, destructive fishing techniques and climate change.
Find out more about habitat loss and degradation

Directed take
Hunting and egg collection for consumption are major causes of the drastic decline in marine turtle populations around the world. Green turtles are caught for their meat, eggs and calipee. Calipee is the green body fat that has given the turtle its name and it is the main ingredient in turtle soup.

Researchers estimate that each year poachers take 30,000 green turtles in Baja California and that more than 50,000 marine turtles are killed in Southeast Asia and the South Pacific. Leatherback turtles are killed in some places for their meat and ovaries although in most countries only their eggs are consumed.

Olive ridley turtles have been pursued for eggs and their skin used for leather production. In the 1960s, over one million olive ridley turtles were butchered each year on Mexico's Pacific coast. In many countries, juvenile marine turtles are caught, stuffed and sold as curios to tourists. Marine turtle eggs are considered an aphrodisiac in some countries and eaten raw or sold as snacks in bars and restaurants. In 1996, Mexican authorities seized a truck containing 500,000 olive ridley eggs collected illegally from an important marine turtle rookery.

Trade
International trade in products such as tortoiseshell from hawksbill turtles, green turtle calipee and leather from olive ridley turtles has exacerbated the quantity of directed take of marine turtles.

During colonial times, European countries were the major importers of marine turtle products. Over the past decades, Japan has emerged as the principal country buying shell (known as Bekko) from tropical countries to produce costly handicrafts.

All marine turtle species are currently listed on Appendix I of CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) which prohibits any commercial trade by more than the 166 signatory countries. Even so, trade between non-signatory countries and illegal trade persist.
Find out more about wildlife trade

Indirect take
Each year, tens of thousands of olive ridley, Kemp's ridley, loggerhead green and leatherback turtles are trapped in shrimping operations. Marine turtles are reptiles and have lungs so when they cannot reach the surface to breathe, they drown.

Gill nets and long-line fisheries are also principal causes of marine turtle mortality. Worldwide, hundreds of thousands of marine turtles are caught annually in trawls, on long-line hooks and in fishing nets.
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Climate change
Changing climate and global warming have the potential to seriously impact marine turtle populations. Marine turtles have temperature-dependent sex determination, meaning that an increase in global temperatures could change the proportion of female and male turtle hatchlings and could result in marine turtle populations becoming unstable.

A higher frequency of tropical storms caused by climate change will result in increased nest loss.

Similarly, rising sea water levels threaten to wash out or erode entire nesting beaches. Key marine turtle habitats such as coral reefs are particularly vulnerable to increases in sea temperature. An increase of only a couple of degrees in water temperature is enough to cause bleaching that kills corals and threatens the foundation on which entire communities of species such as marine turtles depend. The 1998 coral bleaching incident is the worst on record, with reports of degradation from countries across all of the world's oceans.

Other stresses such as pollution and sedimentation are likely to compound this threat. Seagrass beds are also increasingly impacted by climate change. Fewer coral reefs and seagrass beds mean less food and refuge for marine turtles so their populations will decline further.
Find out more about the impacts of climate change

Pollution
Marine turtles can mistake floating plastic materials for jellyfish and choke to death when they try to eat them. Discarded fishing gear entangles marine turtles and can drown or render a turtle unable to feed or swim. Rubbish on beaches can trap hatchlings and prevent them from reaching the ocean. Oil spills can poison marine turtles of all ages.
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Disease
Many types of diseases have been observed in marine turtles. Recents reports of a rise in the occurrence of fibropapillomas, a tumorous disease that can kill marine turtles, is of great concern. It has been suggested that the increased occurrence may be the result of run-off from land or marine pollution that may weaken the turtles' immune system, rendering them more susceptible to infection by the herpes-like virus that is thought to cause the disease. On some of the Hawaiian Islands, almost 70% of stranded green turtles are affected by fibropapillomas.

Natural predators
Marine turtles can lay more than 150 eggs per clutch, and lay several times each season, to make up for the high mortality that prevents most marine turtles from reaching maturity. The subtle balance between marine turtles and their predators can be tipped against turtle survival when new predators are introduced or if natural predators suddenly increase in number as a result of human interference.

On nesting beaches in the Guianas, predation by dogs now represents a major threat to marine turtle eggs and hatchlings. In the south-eastern United States, household garbage has become a source of food for racoons. This has led to a major increase in racoon populations and the results for marine turtles have been devastating. On some beaches, racoons now dig up and destroy as many as 96% of loggerhead turtle nests.