Sea turtles are large reptiles that belong to either the family Cheloniidae or Dermochelyidae. They inhabit open and coastal waters and are most recognisable for possessing a hard shell covered in scale-like scutes (with the exception of the Leatherback). The number and arrangement of scutes is different for each species, so can be used as a method of species identification. There are seven known species of sea turtle in existence: Green, Kemp’s ridley, Olive ridley, Hawksbill, Leatherback, Flatback and the Loggerhead. All seven have been classified as endangered, with the critically endangered Kemp’s ridley, (Lepidochelys kempii), considered the most at risk of extinction. There is huge variation between the seven species, from the Kemp’s Ridley which is often smaller than half a metre in length, to the Leatherback, (Dermochelys coriacea), which can reach more than 2 metres. Fossil evidence shows that extremely large numbers of turtles were in existence from as early as 150 million years ago.
Today, demand for turtle products has rocketed and along with destruction of beach nesting sites and ocean pollution, this has had an enormous impact on once vast turtle populations. Despite the numerous differences between species, their life cycle remains relatively consistent, beginning with the female turtles returning to their natal beach in order to lay their eggs (a process known as natal homing, whereby the females return to the beach from which they were born, some 10-15 years later). It is this reliance on both marine and terrestrial environments as part of their life cycle that leaves them exceptionally vulnerable to threats from sea and land combined.
In the marine environment, many turtles get caught as by-catch (accidental catch) by commercial fisheries; are poisoned from pollutants from shipping traffic, oil spills and sewage and are also losing important feeding and nursery habitats, such as coral reefs and sea grass beds. On land, they face a catalogue of threats, including the loss of nesting sites due to coastal development, disturbance from tourism and poaching of eggs and juveniles to support illegal trade.
The killing of turtles for meat or taking of eggs in order to utilise them as a food source has an obvious affect on population sizes. In addition, turtles may be killed for their shells which are a valuable commodity. Although this is illegal in most countries, the laws are poorly enforced and illegal trades thrive, with a particularly high demand for turtle products in South East Asia because of the direct economic benefit and strong cultural traditions. Despite the dramatic and obvious population declines, the harvesting of eggs and of adults remains legal in several countries.
The hunting of other marine species also has a detrimental effect on turtles as hundreds of thousands become by-catch in shrimp trawls and on long-lines every year, and the mortality for those caught is incredibly high. Fishing techniques such as drift netting, dynamite fishing and the use of long lines, also cause a significant number of fatalities.
Ingestion of plastic waste is another significant cause of mortality, with plastic bags being particularly dangerous because they can be mistaken for jellyfish, which make up a large part of a turtle’s diet.
Irresponsible tourism has a significant negative effect on turtle survival. Firstly, females require dark and quiet beaches for nesting and the increasing popularity of beaches as tourist destinations makes it less and less likely that they will meet these requirements. Artificial lighting is also a problem when hatchlings emerge as it disorientates them, making it harder for them to find the sea and leaving them prone to exhaustion and predation for longer. Destruction of nesting habitats to make way for coastal development has huge implications as females return to nest on their natal beach. If there is no longer space on this particular beach or the beach no longer exists it is likely that the female will not nest at all.
The importance of turtles and why we should care
Turtles are of great ecological importance. Sea grass is a component of many turtles’ diets, particularly the Green turtle and their grazing helps the grass to spread and remain healthy. Sea grass is not only important for the turtle, but for many other species as both a food source and a breeding and development site. Loss of sea grass would directly affect the many other species that are reliant on this habitat and could lead to extinction.
Another key role that turtles play a part in is in the formation of beaches and dunes. These environments often lack nutrients, which is why so few plant species inhabit them. Nesting females will lay 3-7 clutches of around 100 eggs on the beach. Not all eggs hatch and not all hatchlings make it to the sea; those that are not picked off by predators and the discarded eggshells contribute nutrients to beaches and dunes, strengthening vegetation. Healthy dune vegetation helps to prevent beach erosion and our beaches act as buffers between sea and land as natural flood defences. Turtle hatchlings also form part of an important food chain as they are a vital food source for many species of bird and reptile.
Turtles are also of great economic benefit. Eco-tourism brings vast amounts of money in to a region and if done responsibly, grants the opportunity for people to see turtles in their natural habitat. Preserving the habitat where turtles nest provides jobs for local people. If a conservation project is established in a region where there are nesting turtles, there is a need for accommodation, transport, research, education and the training of volunteers, which increases employment opportunities and boosts the local economy.
The solution: what we can do
Demand for turtle products is particularly evident in the East and this arises from the turtle’s role in Asian culture; for example, in China, turtles are not only a delicacy, they are also used in traditional medicines that proclaim a wide range of health benefits, including boosting the immune system and improving sexual performance. Not consuming or purchasing turtle products is the obvious way to begin to eliminate the illegal trade, but we can also consume less tuna, shrimp and swordfish as the catching of these species can harm turtle populations. A range of ‘turtle friendly’ products could be produced, akin to the ‘dolphin friendly’ campaign; these would include tuna, shrimp and swordfish products that are caught using methods that do not harm turtles (for example, equipment with turtle excluder devices). Using fishing equipment with turtle excluder devices (TEDs) fitted and encouraging anybody else you may know who fishes to do the same is an effective way of preventing turtle mortality as a result of becoming by-catch. As well as promoting the use of TEDs, boycotting products caught by nets or trawls lacking them would also encourage their use.
Education programmes could be a very effective method of encouraging conservation, particularly in countries where the culture produces a demand for turtle products as people may not be aware of the extreme detrimental effect that continuing turtle-based traditions may have in the long term. Providing education programmes in countries where turtles are not a part of the culture could also be beneficial with respect to raising awareness of the turtle’s plight and encouraging actions like only eating turtle friendly products.
Simply ensuring that you leave no litter on a beach can make a huge difference. Discarded plastic bags are a particular issue due to the high chance that they will be ingested if they cross the path of a turtle. Taking this one step further and not using plastic bags altogether would have an enormous benefit, not only with regard to sea turtles, but for the environment in general. ‘Bags for life’ can be found in all supermarkets and are a cheap, endurable and sustainable alternative.
Any turtle beach you visit is likely to have its own regulations (particularly for nesting season) and these will include things like not visiting the beaches at night to avoid disturbing females, avoiding walking at the back of the beach where the nests are located and turning off any artificial lights (such as those from hotels backing onto the beach). Just following these simple rules and encouraging others to do the same can be a valuable contribution to sea turtle conservation.
Conservation projects have been established in many countries to protect nest sites against poaching. Many of these projects are run by organisations that use volunteers to monitor nest sites and conduct beach patrols to ward off poachers. Fees from volunteers for accommodation, meals and transport help fund the projects and, in turn, funds get invested back into the local economy, providing employment for local people and a sustainable alternative to poaching. Projects such as these have reduced poaching considerably over the last 20 years and many continue to be a success, however, it relies on a good working relationship with the community and a good number of volunteers per nesting season. For conservation programmes to succeed, the socio-economic factors of a region need to be considered as well as the ecological, as these are what ultimately drive people to exploit animals and their habitats. The incentives and benefits to conserve turtles (be it financial or other) must be greater than the incentives to exploit them. Nations need to become aware of the benefits of having turtles nesting on their shores and swimming in our oceans, valuing them in life and not just seen as mere profitable commodities. International frameworks such as CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), an international agreement between governments to ensure that international trade in specimens of wild animals and plants does not threaten their survival, need to enforce their existing laws and close the many loopholes that exist under the treaty. Countries that have signed up to the treaty need to uphold their end and put in place stronger measures of control and enforcement in international trade.
Although there have been positive steps forward towards the conservation of sea turtles, there are still some major issues that need addressing. Effective monitoring of fisheries by-catch is lacking and coastal development affecting breeding sites is still occurring at a high rate. While there are several examples of relatively successful conservation projects, turtles that have already lost natal beach sites are not likely to nest anywhere else and the effects of this will lead to a further decline in numbers over the next 20-30 year period.