Tuesdays with Turtles – Hiatus Edition

Man, I have a serious case of the summer blahs and am in desperate need of a vacation. Anyways, can’t think very hard. Here’s a nice picture though, courtesy renoir7777’s photostream on flickr.

Man, I have a serious case of the summer blahs and am in desperate need of a vacation. Anyways, can’t think very hard. Here’s a nice picture though, courtesy renoir7777’s photostream on flickr.
Follow eleven turtles as they sprint from Costa Rica to near the Galapagos. Each of them has a corporate sponsor, and at 20 miles an hour, they will get there in a couple of weeks! I think Billie’s going to win, but the leatherback turtle is in bad shape, endangered due to poaching, adult mortality and habitat loss. They may be gone very soon.
Here’s the flickr page for the race, some beautiful pictures already.
In case I forgot to mention, the Olive Ridley arribada started during the 2nd week of February, so about 50 days later, here they are, the “millions” of hatchlings.
The Hindu News Update Service
Olive Ridley hatchlings emerge in Gahirmatha
Kendrapara (Orissa), April 10. (PTI): Millions of tiny olive ridley sea turtle hatchlings are now emerging out of nests at the Gahirmatha beach in Orissa’s Kendrapara district, wildlife officials said on Monday.
The eggs laid by thousands of adult females in the Nasi-2 and Babubali islands in the Gahirmatha marine sanctuary have began to hatch over the last two days, they said.
Wildlife officials stationed at the nesting grounds were witness to the phenomenon, but tourists and researchers were not allowed into the unmanned territory close to the Wheeler’s island where a defence test range is located.
India’s intermediate range nuclear-capable missile Agni III is likely to be test fired from there some time this week, defence sources said.
You know what, the fact that this area is under close military supervision because of India’s grandiose missile dreams may not be sucha bad thing (sacrilege!!!). The area is under so much development pressure that even military operations are better than the alternative.
For more about the Gahirmatha area, visit the official website. At this point in time, the Arribada is very tourist unfriendly, and there are few, if any volunteering opportunities. I will keep any eye open for changes
Technorati Tags: olive ridley, sea turtles
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!
Following up on the fishing issues from last week, here’s word that lights used to lure tuna towards longline fisheries attract juvenile sea turtles as well.
Article – Science & Technology – Lightsticks may hold deadly attraction for sea turtles
RALEIGH, N.C. Longline fishermen use lightsticks similar to the glowing tubes that delight trick-or-treaters to lure tuna and swordfish to baited hooks. New research by University of North Carolina-Chapel Hill scientists suggests that for endangered sea turtles the lights may hold a fatal attraction.
Lab experiments by Ken Lohmann, a University of North Carolina biology professor and John Wang, a graduate who is now a research associate at the University of Hawaii and National Marine Fisheries, found that young loggerhead turtles in a tank tended to swim toward lights.
It’s well known that hatchling turtles on a beach will crawl toward lights as they try to find the surf. But researchers did not know whether juvenile loggerheads in the water shared that attraction. Young loggerhead and leatherback sea turtles, which are protected because of declining numbers, are inadvertently hooked during longline fishing.
Well, not so surprising, is it? Bioluminescence is a common enough phenomenon that especially at night, animals will be attracted to light as it can signal food. It’s tricky, but when you try to catch fish, tyou will catch other animals as well. So, when you change something about the way you catch fish, you need to study how it affects other endangered species…
Off topic, but it is ironic that I read this in the ocregister, which is a newspaper from Orange County, California. It reported on work done by UNC Chapel Hill, which is in Orange County, North Carolina.
WWF – Fishing Technology That’s Letting Turtles Off the Hook –
Turns out that a small change in hook design can save a lot of turtles from getting caught in longline hooks. But the story’s not really about the shape of the hook. I’ve written about this before. The issue is rarely one of technology. The solutions have been developed and exist because a lot of work has gone into developing technological solutions. Implementation on the ground (or sea!) has lagged because it is much harder to effect change where it counts when you attempt to impose technology in a top-down fashion. Small scale fishers (new english here, to avoid the whole fishermen/fisherwoman/fisherperson nonsense, take out the gender specific suffix to every occupation describing verb! – Try it, it’s not weldman, or plumbwoman!) are in a world of hurt with declining fish stocks and widespread fisheries piracy by the so called “developed world”. Without developing and implementing the solution with the full participation of the people who have the most potential to be affected, the change will not be successful.
What did the WWF do differently this time?
Together with fishermen we are building a culture for sustainable fishing practices that will guarantee fish stocks in the long term
They emphasized the people, not the solution. And the results were great, 90% reduction in turtle catch, >95% of the turtles caught were released safely, and the fish yields were not affected. Everyone wins, right?
Good stuff. Those turtles are still endangered and we’ll run out of wild edible fish in 50 years, but hey, more like this and there’s a bit of hope.
You see the hatchlings as they dig out of the nests all small and helpless and make a beeline towards the sea. You see the adult female as she comes back to lay her eggs. You see adult males when you go snorkeling , but the juveniles had kept a low profile, until now…
Sea turtles’ mystery hideout revealed – LiveScience – MSNBC.com
Once sea-turtle hatchlings hit the surf, they vanish for up to five years. Where the half-dollar-size tots spend these ‘lost years’ while ballooning to the size of dinner plates has been a mystery, until now.
New research, published in the online edition of the journal Biology Letters, indicates the green sea turtles (Chelonia mydas) hide out in the open ocean, where they feast on jellyfish and other marine creatures.
Turns out that they’ve been “hiding out” in the open ocean eating meat to augment their vegetarian adult diet. I have not seen the paper (reference below), but the study was based on an analysis of their shell content. Carbon and Nitrogen isotope analysis was used as a marker for diet and location.
The ‘lost years’ of green turtles: using stable isotopes to study cryptic lifestages
Kimberly J. Reich, Karen A. Bjorndal, Alan B. Bolten
Archie Carr Center for Sea Turtle Research, Department of Zoology, PO Box 118525, University of Florida, Gainesville, FL 32611, USA