I have a few minutes of down time, so I thought I'd try to answer some of the questions a few of you have posted.
1. Why did I choose turtles for my Earthwatch expedition? I was in Costa Rica for the first time this past August, and, during that trip, I had the opportunity to see green sea turtles come ashore on the east coast and lay eggs. It was such an amazing thing to witness that I was more than happy to come back down here, this time to the west coast, and learn more about sea turtles in general and leatherback turtles in particular.
2. Why/How did the leatherbacks become endangered? I'm going to couple this question with another one: What is the biggest predator of the leatherback turtle? The simple, and true, answer to both questions is Human Beings. 20-30 years ago it became a fad of sorts to eat leatherback turtle eggs. Men saw it as a 'manly' thing to do to have a raw leatherback egg with their beer, so the eggs were readily available -- and in high demand -- in bars. Others coveted the eggs as a kind of status symbol, a way to one-up their friends -- "I have something you don't have." Consequently, with no laws in place to protect the eggs, poachers would come out every night during nesting season, take every single egg in the nest, keep a few for themselves, and sell the rest to interested buyers. The poaching didn't cause an immediate problem because there were still plenty of leatherbacks during the time of the poaching, so no one really noticed any change in the leatherback population. Jump ahead a generation or two of leatherbacks and you find, all of a sudden, an incredibly steep decline in the number of leatherback turtles left in the ocean.
Over-fishing in the Pacific has also added to the problem. The increase in the number of fishing boats meant an increase in the number of leatherbacks getting caught in fishing nets which, in turn, meant an increase in the number of fishermen not attempting to free the turtles from the nets but, instead, just cutting the nets loose with the turtles still caught in them. I'm sure you can figure out where that led -- and, unfortunately, still leads.
3. Why can't the leatherbacks survive on their own? They can. In fact, once a leatherback is fully grown, it's at the top of its food chain, so, other than the interference from man, the leatherback has no other serious predator (unless, maybe, the odd shark has a hankering that day for leatherback...). What people here at the research station, and in other similar stations around the world, are trying to do is increase the number of leatherback turtles making it to adulthood -- hence, the focus on the nesting and the hatching.
4. What happens if you (Mr. Hill) fall asleep during beach patrol? We're on patrol with at least one, sometimes two, other people, so we help each rouse ourselves and make the sweeps when it's time to do so. To make doubly sure we don't nod off indefinitely, we have a walkie-talkie with us and periodically check in with the others on patrol on other parts of the beach. It's not easy to stay awake, especially during our breaks, but, so far, I haven't needed to be woken up!
5. How many leatherbacks have you seen so far? I have yet to see any; one of the groups on patrol last night saw one. Maybe tonight -- 11 p.m to 5:00 a.m. duty -- will be my lucky night!
6. Why don't the leatherbacks lay their eggs closer to the water? In order to produce hatchlings, the eggs have to be buried deep in the sand, and they have to be able to 'breathe'. If the eggs were nearer to the water, they would be wet a good deal of the time while they were incubating, and that wetness would prevent the eggs from receiving the oxygen and warmth they need. It's for that reason that some nests are relocated to the hatchery: if a turtle lays her eggs inside the high-tide line, the eggs don't stand a chance, so the biologists here, who have marked where the nest is (that's part of night-time beach duty!) will relocate the nest to the hatchery the next day.
7. How many hatchlings survive? If we take human beings out of the picture, Nature allows 1 out of 1000 hatchlings to make it to full adulthood -- which means one of a thousand live for at least 15 years. Factor in what I wrote about in #2 above and the number of leatherbacks making it to 15 is now far far fewer. I'll find out the approximate number for you and report back. If a leatherback makes it to 15, and, again, we factor out human beings, a hatchling -- now an adult -- will live approximately 80 years, though that number's a very rough approximation since there's no way as of yet to find out just how long most leatherbacks live.
Hope those answers make sense to you! I'll try to get to more of your questions tomorrow.
Here's an interesting piece of information: leatherback hatchlings will eat whatever they can fit in their mouths; once the hatchling's bigger, however, he or she will eat almost nothing but... jellyfish! And the poison which several species of jellyfish have at their disposal doesn't affect the leatherback in the slightest. I wonder if the decline in the leatherback population has led to an increase in the jellyfish population -- that would only make sense, right?