Sea turtles are ancient reptiles that as a group have existed mainly unchanged on earth for about 150 million years. Along with other turtles and tortoises they consist of the order Testudines. There are seven living species of sea turtle. The Flatback, Green, Hawksbill, Kemp's Ridley, Loggerhead and Olive Ridley all belong to the family Cheloniidae. The leatherback is the only member of the family Dermochelyidae.
Perhaps the greatest threat to sea turtles is the interaction with humans. Although all marine turtles are protected they still suffer from being caught in fishing activities. It is estimated that over 5,000 turtles are caught in trawling nets each year in the Adriatic Sea. In many cases turtles that are pulled up in trawling nets are alive but in a state of hibernation, correct treatment of these animals can enable the animals to be revived before being put back into the sea. Replacing them in a state of hibernation can result in drowning.
In other regions the use of long-line fishing is believed to be a major factor in sea turtle mortality. Hooks are easily swallowed and may create major damage to the digestive tract if left untreated. above is an xray of the turtle caught on a line near Losinj, it was taken to Pula for the hooks to be removed and survived a very painful experience. However, some relatively inexpensive changes to fishing techniques, such as slightly larger hooks and Turtle Excluder Devices can dramatically cut the mortality rate. In addition thousands of turtles die each year by eating plastic bags, bottles and other rubbish which is thrown into the sea. Floating plastic bags look like jelly fish which is the prey for many sea turtles.
The development of tourism has also affected the nesting sites of these turtles. Lights and noise scare and disorientate adults and hatchlings causing population wide problems. 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 (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. 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 for the production of leather goods. In many countries, turtles are caught, stuffed and sold as curios to tourists, Eggs are considered an aphrodisiac in some countries and eaten raw . 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.