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Sunday, May 9, 2010

Loggerhead sea turtles (Caretta caretta) among others, is a seriously threatened species across the world

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Sea turtles are ancient creatures considered as one among the most important indicators of the health of the world’s marine and coastal ecosystems.

Among sea turtles Loggerheads (Caretta caretta), Leatherbacks (Dermochelys careacea), and Olive Ridleys (Lepidochelys olivacea) are considered as seriously threatened species. These are being brutally and painfully snagged on hooks dragged behind marine boats. It is reported that about 200,000 Loggerhead and about 50,000 Leatherback sea turtles are caught in the world every year. The industrial fishing fleets are killing hundreds of thousands of sea turtles each year besides whales, sharks, sea otters and sea birds in most vicious ways. The greatest threat to sea turtles is loss of nesting habitat due to coastal development, predation of nests, and human disturbances like coastal lighting and housing developments that cause disorientation during the emergence of hatchlings. Incidental capture in longline fishing, shrimp trawling and pollution are other threats to sea turtles. In the recent decline of the population of sea turtles, the incidental capture in fisheries is thought to have played a significant role.

Image : 1 - Loggerhead turtle source - Wikimedia

Image : 2 - Leatherback turtle  source: Flickr

Image : 3 - Olive Ridley Turtle  source : Green peace

Loggerhead sea turtles
Loggerhead sea turtles are amazing creature of ocean. Loggerhead was listed as a threatened species in 1973 and currently it is considered as Vulnerable by the International Union for the Conservation of Nature. The population studies conducted recently concludes that the number of female loggerheads that nest in the South East United States is declining continuously.
Loggerhead sea turtles are so named due to their relatively large heads that support powerful jaws enabling them to feed on hard shelled prey. The top shell or Carapace of a loggerhead turtle is slightly heart shaped and reddish brown in adults while the bottom shell or Plastron is pale yellowish in colour. The neck and flippers are dull brown to reddish brown on top and pale yellow on bottom and on sides. Flippers are dark grey to brown on upper side with   white to white grey margins. The plastron is generally yellowish to tan in colour.

Each loggerhead turtle measures about 92cm in length corresponding to its 250lbs or 113 kg weight. The turtle attains sexual maturity at 35 years of age. The females lay eggs 3 to 5 in number or even more during a single nesting season. The eggs incubate about 2 months before hatching. The hatchlings are usually 45mm in length corresponding to their weight which is approximately 0.04 lbs or 20g on an average.

Loggerheads live through three different types of ecosystems that mean three different parts of the sea- environment, in their lives. These three habitats are the terrestrial zone, the oceanic zone, and the neritic zone. They nest on ocean beaches. A period of frenzied activity starts after hatchlings emerge from the nest. During this period of activity they move towards the sea, swim and are swept through the surf zone. They continue swimming for a few days and come to rest in a residence that is selected by them where surface waters converse to form local downwelling. Here they feed upon different types of floating materials. After a period they join sea waves that transport them to places far away from the coast. This is the oceanic zone where the loggerheads spend some years and swim towards reefs and rocks where they get crabs, mollusks, and other animals and eat them. They crush them between their powerful jaws and get stronger and stronger. In the age of 12 to 17 years they come back towards coastal areas near the shore. This is the neritic zone where they get plenty of food supply. Here they continue maturing up to adulthood. This zone provides them a habitat suitable for foraging, mating, migrating and moving to beaches for nesting and hatching.

Loggerheads are found through out the temperate and tropical regions of the Atlantic, Pacific, and Indian Ocean. Loggerheads are most abundant species of sea turtle found in the coastal waters of United States. Loggerhead nesting in majority can be observed in the western rims of Atlantic and Indian Ocean. About 88 per cent of total nesting of Loggerheads occurs in Oman, the United States and Australia. In the United States the loggerhead nesting areas have been divided among four states – Florida – 91%; South Carolina – 6.5 %; Georgia – 1.5 % and North Carolina -1%. According to a research, the Florida beaches account for one third of the world’s total population of Loggerheads.

Trends of Loggerhead population
Various surveys and studies done at different nesting sites of Loggerheads reveal that the population of these turtles everywhere shows a declining trend. The analysis of the data received from the Index Nesting Beach Survey Programme in Southeast Florida show a declining trend of population. The nesting of Loggerheads has been reported declining in all the four nesting sites of the United States and other nesting sites elsewhere. Very small number of nesting has been reported from Egypt, Israel, Italy, Lybia, and Tunisia. The loggerhead population in Honduras, Mexico, Colombia, Turkey, Bahamas, Cuba, Greece, Japan and Panama has been reported declining.

Efforts for conservation
Since Loggerheads have highly migratory behavior, they have become shared resource among many countries of the world. Thus efforts for conservation of Loggerheads in one country may be weakened through negative activities done in other countries. The conservation efforts done along beaches of any one country, say U.S. is not sufficient to ensure continued existence of the turtle species. The international trade of Loggerheads has been prohibited through international treaties, agreements and international laws. They are listed in Appendix-1 of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). These have also been listed in Appendix I and II of the Convention on Migratory Species. Different Nations of the world have been planning to protect this turtle species through their own efforts as well.

Key Words: Loggerhead Turtles, Leatherbacks, Olive Ridleys, threatened,CITES,Indian Ocean, Atlantic,International laws, Treaties, conventions, neritic zone, oceanic zone, nesting sites, habitatsEgypt, Israel, Italy, Lybia, Tunisia,Florida, South Carolina,  Georgia, North Carolina, migratory species.

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