Green Sea Turtles: Annual Death Toll And Its Causes

Green sea turtles are the world's largest species of hard-shelled sea turtle. They are also the only herbivores among the different species of sea turtles, eating mostly seaweed, seagrasses, and algae. Green sea turtles are found in tropical and subtropical waters worldwide and are classified as endangered. While the number of green sea turtles killed each year is unknown, human activities such as overharvesting of their eggs, hunting of adults, accidental capture in fishing gear, and loss of nesting beach sites pose significant threats to their survival. These factors, along with climate change, have contributed to the decline of green sea turtle populations globally.

Green turtles are killed for their meat, shells, and eggs

The meat of green turtles is consumed by humans, and the trade of their body parts remains a profitable business. In parts of Asia and the Western Pacific, tens of thousands of green turtles are harvested annually. Despite complete protection in some areas, such as the Eastern Pacific coast of Mexico, green turtles remain vulnerable to exploitation. Additionally, in West Africa, they are killed for use in traditional medicine and ceremonies.

The shells of green turtles are also sought after by the wildlife trafficking trade, contributing to the threat facing their recovery. The illegal trade of turtle shells and meat persists, despite efforts by organizations like the World Wildlife Fund (WWF) to stop it.

Green turtles are further endangered by the overharvesting of their eggs. Their eggs are harvested for human consumption, and the trade of turtle eggs is a significant contributor to the decline in the green turtle population. WWF works with local communities to reduce egg collection and promote the value of sea turtles.

The killing of green turtles and the collection of their eggs for meat, shells, and eggs have severe consequences for their population. These practices, along with other threats like bycatch in fishing gear and loss of nesting habitats, have led to their classification as an endangered species. Conservation efforts by organizations like WWF and NOAA Fisheries aim to protect and recover green turtle populations worldwide.

They are also killed accidentally as bycatch in commercial fishing

Green sea turtles are the world's largest species of hard-shelled sea turtle and are unique among sea turtles as they are the only herbivores, eating mostly seaweed, seagrasses, and algae. They are found in tropical and subtropical waters worldwide and nest in over 80 countries.

While it is difficult to determine the exact number of green sea turtles that are accidentally killed each year, they are indeed vulnerable to accidental death as bycatch in commercial fishing. This is when they are unintentionally captured in fishing gear, which can result in drowning or cause injuries that lead to death. For example, they may swallow hooks or become entangled in fishing lines.

Green sea turtles are particularly susceptible to becoming bycatch in shrimp trawl nets, longline hooks, and fishing gillnets. Global estimates suggest that hundreds of thousands of sea turtles of all species are accidentally captured in these types of fishing gear each year. For instance, it is estimated that 150,000 turtles of all species are killed in shrimp trawls annually. The threat of being caught in fishing gear is increasing as fishing activity expands.

To address this issue, measures such as changes to fishing practices and gear modifications have been implemented. For instance, Turtle Excluder Devices (TEDs) have been developed to reduce sea turtle mortality in shrimp trawls. These devices are now mandatory for shrimp fishers in the United States. Additionally, the United States has prohibited the importation of shrimp harvested in ways that adversely affect sea turtles.

However, despite these efforts, sea turtles continue to be at risk of accidental death as bycatch in commercial fishing. This is due to factors such as non-compliance with regulations, expanding fishing activity, and the difficulty of completely eliminating bycatch in certain types of fishing.

The accidental capture of green sea turtles in commercial fishing gear is a significant threat to their populations and conservation efforts. It is important to continue implementing measures to reduce bycatch and protect this endangered species.

Coastal development and human activity have destroyed their nesting beaches

Green sea turtles are the world's largest species of hard-shelled sea turtle, and the only herbivores among the different species. They are found in coastal areas of over 140 countries, nesting in over 80 of them. Coastal development and human activity have destroyed their nesting beaches, threatening the survival of this species.

Green turtles are solitary, night-time nesters. They migrate hundreds to thousands of kilometres between their foraging grounds and nesting beaches. They nest every two to five years, returning to the waters off the beaches where they originally hatched to reproduce. They lay their eggs on land, and the hatchlings then make their way to the sea.

Human activity poses a significant threat to this natural process. Artificial lighting on and near nesting beaches can deter female turtles from coming ashore to nest and disorient hatchlings trying to find the sea. Coastal armoring, such as seawalls, can result in the loss of dry sand suitable for successful nesting. Beach driving and the presence of beach furniture and recreational equipment can also negatively impact nesting turtles, reduce nesting success, and increase the risk of entrapment.

In addition to coastal development, human activities such as vehicle traffic on beaches, uncontrolled tourism, and coastal residences have disturbed and destroyed sea turtle nesting habitats. Sea turtles face competition from humans for the use of beaches, which can discourage female turtles from nesting and affect the chances of producing successful nests.

The combined effects of these human activities have substantially altered sea turtle nesting beaches worldwide, threatening the survival of green sea turtles.

Climate change is impacting their nesting sites and food sources

Green sea turtles are the world's largest species of hard-shelled sea turtle. They are unique among sea turtles in that they are herbivores, eating mostly seaweed, seagrasses, and algae. Climate change is having a significant impact on their nesting sites and food sources, threatening their very existence.

Firstly, climate change is causing a rise in sea levels, which directly affects the nesting beaches of green sea turtles. These turtles have a unique ability to return to the same nesting site decades later to lay their eggs. With melting polar ice caps and rising sea levels, these beaches are disappearing, and it is becoming increasingly difficult for turtles to find suitable spaces to deposit their eggs. This leads to decreased nesting activity and, consequently, fewer sea turtles being born.

Secondly, the warming oceans are impacting the sex ratio of hatchlings. The temperature of the sand in which the eggs incubate determines the gender of the hatchlings, with cooler temperatures producing males and warmer temperatures producing females. As climate change increases sand temperatures, there is a shift towards a higher ratio of female hatchlings. This imbalance in the sex ratio can create a significant threat to the genetic diversity of green sea turtle populations and impact their ability to reproduce in the future.

Additionally, warmer ocean temperatures are associated with lower productivity and, thus, less food availability for many organisms, including green sea turtles. This decrease in food sources leads to reduced nesting activity and a decline in the birth rate of sea turtles. Warmer oceans can also change ocean currents, potentially exposing green sea turtles to new predators and further disrupting their food sources.

The effects of climate change on green sea turtle nesting sites and food sources are already being monitored in some populations, such as in the Western Pacific and Western Atlantic Oceans. As climate change continues to impact their habitats and food sources, the existence of green sea turtles is increasingly threatened.

Marine debris and pollution are causing green turtle deaths

Green turtles are under threat from marine debris and pollution. They may ingest marine debris such as plastic bags, balloons, fishing line, and other discarded materials, mistaking them for food. This can lead to choking or blockage in their digestive system. They may also become entangled in marine debris, such as lost or discarded fishing gear, and drown or be seriously injured.

Pollution from oil spills, urban runoff of chemicals, fertilizers, and petroleum also poses a significant risk to green turtles. These pollutants contaminate and kill aquatic plants and animals that are a food source for green turtles. As the toxins break down, they become more concentrated and are consumed by the turtles, leading to unknown health risks.

Furthermore, marine debris and pollution can degrade and destroy the habitats of green turtles. Coastal development and rising sea levels reduce nesting beach habitats. Artificial lighting on and near nesting beaches can deter females from coming ashore to nest and disorient hatchlings. Climate change is also altering beach morphology and sand temperatures, which can be lethal to eggs and impact the ratio of male and female hatchlings.

The impact of marine debris and pollution on green turtle populations is difficult to quantify, but it is clear that these threats are contributing to the decline of green turtle populations worldwide.

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