Tuesdays with Turtles – Must See TV Edition

If you did not know already, sea turtles tend to nest on (or close to) the beaches they were born at. It is known that they use the Earth’s magnetic fields to navigate. Here’s an article on the navigational natations (I strain to alliterate at times, but natation means swimming!) of the Green Turtle.

ScienceDaily: How Do Marine Turtles Return To The Same Beach To Lay Their Eggs?

I flagged this article not because it tells us much new, but just adds some nuances to sea turtle navigation.

The study has shown that the marine turtles’ navigation system allows them to maintain their course towards the egg-laying site wherever they find themselves. It is almost as if they were equipped with a compass pointing towards the beach in question. So they can correct any deflection they are subject to: transport by boat, ocean currents… But, unlike human navigators, they are not able to correct for ocean drift in plotting their course. So the movements recorded by the satellite are a combination of deliberate action by the turtles and the effect of currents. So it appears that the turtles’ navigation system is relatively simple and may cause them to be wander at sea for long periods during adverse ocean conditions. One turtle released 250 km from its egg-laying site on Europa traveled more than 3 500 km in two months before returning there!

Well, that’s interesting, if not surprising. It’s one thing to have a magnetic bookmark of a destination in your head (pretty wonderful thing, I wish I had it!) and swim continually towards this destination. It’s quite another thing to keep track of complex parameters like ocean drift and keep correcting continuously.

In essence, what they’re saying is that turtles home in on their destinations, but don’t always take the shortest way in because they tend to drift and not correct for this drift dynamically. It is not evolutionarily necessary because turtles probably do not get thrown way of course often enough that evolving even more sophisticated navigational systems (Garmin?) would provide a significant enough survival advantage.

In the Mozambique Channel, between the east coast of Africa and Madagascar, on the beaches of the French Islands of Europa and Mayotte, they caught turtles at the beginning of their egg-laying cycle, so that the animals were strongly impelled to return to this area to complete their cycle. After having Argos transmitters fitted to their shells in order to satellite track their return journey to the beach, the animals were released in open sea, several hundred kilometers from the egg-laying site.

Now that’s just mean! Imagine being kidnapped, tagged and released many miles away from home, and having to find your way back. Apparently, these turtles did it. Man, that would be such a cool navigational aid to have, quite a party trick!

Now you know what to do when you hit Jekyll island, GA (no, don’t Hyde!)

NPR : Loggerhead Turtles Draw Georgia Tourists

It helps that they’re such handsome beasts.

Personal Note
I swear, this blog has gone to pot. Either I’ve been too busy at work (yes, that does not explain everything), or I have not been thinking enough. I started this blog so that when I saw something interesting, I would have to think a little bit, and gather some information to write about what I saw/read. Apparently, I don’t read/see any more (which is not true), I don’t think any more (possible), or I am too lazy to spend enough time thinking to throw a coherent blog post together.

This has got to stop, and it stops right now!!
End Personal Note
Back to the topic on hand…

The Pacific Leatherback is in serious trouble and is slated to go extinct soon.

ENN News Network

Experts at the Bellagio Sea Turtle Conservation Initiative have just concluded a conference to save the imperiled Pacific leatherback sea turtle from extinction. The International Union for the Conservation of Nature and Natural Resources (IUCN) has classified Pacific leatherbacks as critically endangered.

The meeting convened an internationally diverse group of scientists, conservationists, economists, fund-raisers and policy makers. One focus was the development of immediate actions to boost hatchling production of the Western Pacific nesting populations by protecting nests from predation, beach erosion and human consumption on the beaches of Indonesia, Papua New Guinea, Solomon Islands, Vanuatu, Vietnam and Malaysia. Although there are still hundreds of turtles nesting, with 75 percent in one area on the north coast of Papua (Indonesia), researchers are concerned by new information indicating that the majority of nests laid are not producing hatchlings. Some simple procedures have been developed to improve hatch success, and applying these techniques now may ensure the populations are sustained in the future.

Some radical measures have been suggested, including cloning. Well, highly unlikely. Jurassic Park horrors and ethical dilemmas aside, cloning reptiles ain’t so easy.

What ails the Pacific Leatherback? Their numbers have dropped from 115000 reproductive females to less than 3000. This news release from a 2004 conference has more. But the usual suspects are destruction of nesting habitats, long line fishing, egg poaching, and to a more uncertain degree, climate change.

It’s depressing, I’ve never seen a leatherback, I guess I need to get on the case and see one before they disappear for ever.

The Students’ Sea Turtle Conservation Network was featured in the Hindu today.

Sea turtle lovers are concerned at the disturbance caused to turtle nesting habitats along the Tamil Nadu coastline, where casuarinas have been raised by the State Forest Department.The sea turtle’s egg-laying season began a month ago. Volunteers of the Chennai-based Students’ Sea Turtle Conservation Network (SSTCN) had written to the World Bank stating that the Forest Department should reverse the damage done.The SSTCN also wanted the Bank to provide funds for taking up transplantation work.Akila Balu, co-ordinator, SSTCN, said after the tsunami, the World Bank funded an Emergency Tsunami Reconstruction Project (ETRP) in Tamil Nadu.Under this programme, the State Forest Department had taken up the work of raising casuarina plantations to act as a bio-shield on the coastline. The casuarina saplings were planted right up to the high-tide line. In the process, it eliminated large stretches of sea turtle nesting habitat.Department’s defenceA senior Forest Department official said casuarinas had not been raised all along the State coastline.Adequate space had been provided between each sapling through which the turtles could enter the sand and lay eggs.The ETRP is a conservation-oriented programme, and so far the department has not received any complaints that the casuarina plantation had affected egg-laying of the Olive Ridleys, the official said.“In most of the areas, the saplings are not touching the high-tide line. If we plant closer to the line, the saplings will not survive. On the whole, the plantation will surely not affect the egg-laying turtles,” the official added.

The Hindu : Tamil Nadu / Chennai News : “Casuarina plantations affecting turtle nesting habitats”

To find out more, visit the SSTCN website.

cross-posted at the Students’ Sea Turtle Conservation Network

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Tags: SSTCN, Olive Ridley, Sea Turtles, Chennai