Loggerheads are amazing… highly migratory and particularly vulnerable to accidental capture in the nets and long-lines of the world’s fisheries. Although Turtle Excluder Devices (TED), fitted into shrimp nets in some countries have lessened the threat, the use of these devices is not yet mandatory everywhere. Longline by catch mitigation trials are also being conducted in several places across the world, but will they be in time to halt the decline? Their present population is 60,000 + nesting females.
I have had the pleasure of spending a fair amount of time with Loggerhead Turtles off the coast of Belize from 1999 – 2003. At certain times of the year, they were fairly present along the outer edge of the barrier reef.
On several occasions, I could watch them rising from the depths along the edge of the reef until they were quite literally right beside me. On more than one occasion, they would spot a crab nearby and make a meal of one, seemingly oblivious to my presence. One I saw so often that I named him Seven Barnacles for the seven large barnacles he carried with him (see photo at right). On more than one occasion, I attempted to swim alongside them until they seemed to realize I was there and with a few powerful fin sweeps, would leave me breathing far too heavy 60 feet under the water.
On one particular dive, it became quite apparent how poor their visibility was when one large Loggerhead swam straight towards myself and a student until it was literally so close that I had to reach out and place my two arms on the shell and push it away for fear that it was simply going to swim directly into the student I was teaching.
The loggerhead turtle has a rusty coloured carapace. It is one of the largest turtles, weighing about 155 kg and carries more encrusting organisms such as barnacles on its shell than the other marine turtle species. This species is distinguished mainly by its large head and strong jaws. As with leatherbacks, loggerheads are highly migratory, making some of the longest journeys known of all marine turtle species. The possibility that juvenile loggerheads cross the Pacific Ocean has been corroborated by studies showing Baja Californian loggerheads have a genetic affinity with those found in Japan, and recently the first trans-Pacific migration of a loggerhead was recorded with a satellite transmitter. It is thought that an ability to detect wave direction and the Earth’s magnetic field enables this species to navigate across open oceans.
Nesting Range States
Angola, Australia, Bahamas, Bangladesh, Belize, Brazil, Cape Verde, most of the Caribbean, China, Colombia, Costa Rica, Cuba, Cyprus, Egypt, Greece, Guatemala, Honduras, India, Indonesia, Israel, Italy, Jamaica, Japan, Libya, Madagascar, Mexico, Morocco, Mozambique, Namibia, New Caledonia, Nicaragua, Oman, Panama, Philippines, Senegal, South Africa, Sri Lanka, Turkey, Turks and Caicos Islands, USA, Venezuela, British Virgin Islands.
Why is this species important?
Marine turtles fulfill important roles in marine ecosystems. Loggerhead turtles eat many types of invertebrates, in particular molluscs and crustaceans, and can change the seabed by “mining” the sediments for their favourite prey. Also, loggerhead turtles carry veritable animal and plant cities on their shell. You can see from my photos just why I named one of these turtles Seven Barnacles. As many as 100 species of animals and plants have been recorded living on one single loggerhead turtle. These animals and plants depend on turtles to have somewhere to live and to prosper.
The future for many of these species is intimately linked to our care of the oceans.