There are currently eight recognized species of sea turtles: the loggerhead, the Kemp’s ridley, the olive ridley, the hawksbill, the leatherback, the Australian flatback, the green turtle, and the black turtle. These turtles differ greatly in size, coloration of carapace, feeding habits, lifestyles, and habitats among many other things. One thing that they do all share in common though is the fact that all of them are currently endangered or threatened species.
Many natural causes have led to the deaths of sea turtles. Natural predation is probably the greatest of these. Like any other animal, sea turtles too have their place in the food chain. Baby sea turtles run the greatest risk of being eaten by other animals. The period from when they hatch and emerge from their nest and attempt journey across the beach to the sea is perhaps the most vulnerable period of their life. Many of them are snatched up and eaten by birds, ghost crabs, coyotes, ants, raccoons, and feral pigs and dogs. Even when they reach the ocean, most baby turtles still remain vulnerable because of their small size. In fact, the odds are one in a thousand for a baby turtle to reach adulthood when it would be mature enough to reproduce. Larger sea turtles are usually safe, but occasionally some are eaten by sharks and orcas in the ocean and by jaguars on nesting beaches.
Nature has put many other obstacles in the way of survival for modern sea turtles. Drastic changes in weather patterns such as those caused by El Ni–o were the source of high tides, severe droughts, and hurricanes that destroyed millions of turtle eggs. In Mexico, Hurricane Pauline, a storm caused by El Ni–o in 1997, destroyed 6 million eggs on one beach in Escobilla.
The food chain and the weather aren’t the only obstacles that Mother Nature has created for the sea turtles. Just this past winter a mystery disease swept through the loggerhead population off the coast of the United States and it is still affecting them today. Dead turtles were washing up on beaches and many more ailing ones were found floating in the ocean, paralyzed and unable to move. The true extent of this disease is hard to estimate since most of the dead and sick turtles are never even found. What is scarier still is that even in the very best conditions, the sick turtles aren’t recovering well at all which leads scientists to believe that large numbers of them are dying in the wild. There are a few theories as to why the loggerheads are dying, one says that this is the result of a new infectious disease while another claims that it is a toxin in something that the loggerheads eat that is having these fatal effects. The toxin theory seems to be gaining ground since only the loggerheads are getting sick and they are the only carnivorous sea turtle in the area; green turtles have not been effected. Local fishermen have also been reporting a new kind of jellyfish in the area, perhaps this is the cause but scientists have yet to find out.
Despite the toll that all of these natural causes have taken on the modern day sea turtle population, they are nothing next to the effects that humans have had in the last hundred years. It is mainly because of human development and action that the sea turtles are being pushed closer and closer towards the brink of extinction. There are a number of things that we have been doing to hurt the turtles, the following are just a few of them.
Just as with many other species throughout the world, at one time in the past, humans were able to kill and eat turtles at a subsistence level that had very little impact on the turtle populations as whole. Unfortunately though, in the last hundred years, this has not been the case. People have had a very direct and large impact on the turtles by taking their eggs and killing them for meat. Turtle eggs have been used as food, in baked goods, and in some countries as aphrodisiacs. The adult turtles have been killed for meat, for their shells, and for their skin. Their shells and skin are used to make jewelry, shoes, and trinkets that are often times sold to tourists. Even though many countries have made it illegal to take turtle eggs or to trade their skins, these laws are not always enforced and the killing continues.
The accidental killing of sea turtles has also been a major problem. Most of this is caused by the commercial fishing and shrimping industries. In fact, according to the National Marine Fisheries Service, "drowning in shrimp trawls is considered the greatest threat to the turtles' survival.” They estimated that over 11,000 turtles drown in trawl nets each year. Turtles need to come up to the surface for air and when they are caught in nets they usually can’t come up and waste even more of their energy and oxygen trying to fight free. Fortunately, Turtle Excluder Devices, often called TEDs for short, were invented. These devices drastically reduce the amount of large sea animals such as turtles that are caught in the shrimp nets while still catching almost the same amount of shrimp. The United States government mandated the use of TEDs in the southeastern USA in 1994 and just this past year, similar laws along with limits on fishing and shrimping in certain areas were appearing in legislation in Texas. Even though TEDs are being used in the US, there other countries that are not employing them. The US has tried to pressure other nations into creating regulations that include the use of TEDs by banning the import of shrimp from nations that still endanger sea turtles.
Litter is another manmade problem that has affected sea turtles along with birds and many marine mammals. Often times when plastic bags and balloons are thrown out or land in the ocean, they look similar to jellyfish floating in the water. When the turtles and other animals try to eat this garbage, it can block or infect their stomach or intestine and they end up dying slowly of starvation.
Next to the dangers caused by the fishing industry, human activity and development along the beaches that sea turtles use to nest has probably had the second largest negative impact on the modern population. When there are more people present on the beach, the turtles are less likely to come out of the ocean to lay their eggs and if they do, they are often scared away and return to the water without nesting. The artificial lights of beachfront buildings and streets and from the headlights of cars will also scare away female sea turtles. In addition to scaring away adult females, these lights can confuse baby turtles that have just emerged from a nest. Under normal nighttime conditions, the ocean is usually lighter than the land and the baby turtles head towards the lighter area in search of the water. When artificial lights are introduced into the picture, they can disorient them and send the baby turtles wandering off in the wrong direction during this extremely vulnerable point in their life. Beach raking and renourishment (the addition of new sand) have also hurt the turtles by disturbing nests and when done with large machinery and tractors, by crushing nests or the emerging hatchlings that have just broken free of them.
Luckily, there are lots of people who care about sea turtles and don’t want to see them disappear. These people have been working hard to change things so that both people and turtles can both live in this world. The United States and many other nations have passed laws that protect sea turtles and make it illegal to trade or sell turtle products. They have also passed legislation that makes fishing safer for larger sea animals. The Convention on International Trade in Endangered Species of Wild Fauna and Flora, an international treaty that gives protection to endangered animals by the countries that have signed it, includes sea turtles as one of the species that are banned from international trade. Governments have also set aside pieces of land where the turtles nest as wildlife refuges to protect their habitats. In addition to creating protective laws to help save the sea turtles and setting aside land, there are many universities and research centers set up all over the world to study their behavior, migration, and population trends. Just like the research centers in Florida who are trying to help the loggerheads, these scientists are helping the turtles by giving us a better understanding of how they live and therefore impacting the strategies that are used to save them. Many local people who live in areas where sea turtles nest are also being included in the efforts to help the turtle population recover. Costa Rica seems to be at the forefront of this. ANAI in Gandoca and ADIO (Asociacion Desarrollo Intergral de Ostional) in Ostional are examples of places that include local people in their efforts to save the turtles. They also help the people to benefit in different ways economically, by having a part in the ecotourism or by a limited and closely regulated harvest of some eggs. There are also conservation groups that are trying to help by educating people in many different countries and of many different backgrounds and making them aware of what is going on. All of these efforts of these varied groups are necessary if the sea turtles are going to survive us, their greatest challenge to survival. Hopefully they will be successful and people will learn how to share this planet with the other creatures that inhabit it with us.
Sources
1) “Endangered Sea Turtles Battle New Enemy: El Ni–o.” 13 Nov 1997. Available Online. http://www.cnn.com/EARTH/9711/13/nicaragua.turtles/
2) Foley, James B. Press Statement On Sea Turtle Conservation and Shrimp Imports. 4 May 1998. Available Online. http://secretary.state.gov/www/briefings/statements/1998/ps980504.html
3) Lepthien, Emilie U. Sea Turtles. New York: Grolier Publishing, 1996.
4) Ripple, Jeff. Sea Turtles. Stillwater, MN: Voyageur Press, 1996.
5) Sierra Club. “Help Protect Endangered Sea Turtles Off The Texas Coast.” 2000. Available Online. http://texas.sierraclub.org/alerts/seaturtle_alert.html
6) Swanson, Stevenson. “Experts Hunt For Clues To Mysterious Turtle Illness.” Chicago Tribune. 26 Jan 2001.
7) “TED Case Study: Shrimp and Sea Turtle.” Available Online. http://www.american.edu/ted/SHRIMP.HTM
For Further Info on this Topic, Check out this WWW Site: www.muohio.edu/~germanjm/frogs.
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