In the May 2001, students interviewed Dr. Frank Paladino, one of the lead biologists for the Leatherback Research Project at Las Baulas National Park in Costa Rica.
Question: How have the TEDs helped the fight for sea turtle survival in recent years?
Paladino: One of the most dramatic declines occurred after the shrimping industry started to intensify their efforts in the Gulf - the shrimping industry really devastated the sea turtle populations. And the Turtle Excluder Devices, or TEDs, were very important in preventing this form of fisheries from having an effect on turtles.
The reason why the shrimping industry had such an impact was because they were killing reproductive adult females.
As hatchlings, turtles are very susceptible to predation all the fish and everything wants to eat them as hatchlings. But as adults, they have very few predators and live very long lives. And the shrimping industry was changing that by killing adult females that were returning to the nesting beaches. Now that has been greatly reduced, and the reproduction of the remaining females is much more successful.
Question: Are the turtles in danger? How many are left of the endangered species?
Paladino: The rarest of the sea turtles is the Kemp's Ridley sea turtle. And it's estimated that there may be 10,000-20,000 of these left in the world. In 30 years, the numbers of these turtles that would nest on one beach in Mexico changed from 20,000 a night, to now, where there are only a few hundred. So, this dramatic decline was due primarily to human effects. They were being caught in shrimp nets, and this destroyed the adult population.
The protection of the beaches and now the adults with these TEDs have allowed a recovery of this group. However, all seven species of sea turtles are listed as endangered or threatened, which means their populations have declined more than 50 percent in the past ten years.
Question: How long do sea turtles live?
Paladino: Sea turtles are fairly long-lived, with an average age for all seven species of 45 to 50 years old in the wild. There are some that are known to have lived to as much as 70 years of age.
Question: How are sea turtles different from regular turtles?
Paladino: Sea turtles are different in that they have salt glands in their eye orbit, which allows them to live in a marine environment, in saltwater. The other factors that are different is that they tend to be much larger, and they also have much more specialized flippers for long-distance swimming. Other than that, they're very similar.
Question: Do you have a sea turtle in your home as a pet?
Paladino: Because they're endangered, you're not allowed to keep them as pets. I have, however, had sea turtles from eggs and reared them in the Camden Aquarium in New Jersey.
There are a number of aquariums around the world that have sea turtles in their collection in Chicago, the Shed Aquarium has a Hawks Bill sea turtle. Sea World in Cleveland, in Florida, and in California all have sea turtles in their collections that they display. However, they have special permits to keep them, and the tanks are much bigger than the swimming pools that a person would have in their own house.
Question: How do you study the turtles?
Paladino: There are lots of experiments that we do. But some of the most basic work is to simply tag each turtle with a permanent identity marker, so that we know how many nesting female turtles there are each year. Our other experiments include attaching radio and satellite transmitters to find out where they go and what they do when they're in the ocean.
Question: How large can a sea turtle get? What's the largest sea turtle you've studied?
Paladino: The largest sea turtle that I've studied is a leatherback sea turtle that was 550 kg that's over 1,000 pounds! (about 1,213 pounds) The turtle is about the size of a Volkswagen slug bug, and when its flippers are stretched across, it's about 11 feet, and from the tip of its nose to the tail is about 10 feet. These are the largest sea turtles.
Question: How long will you continue to study the turtles in Costa Rica?
Paladino: We have been on Playa Grande in Costa Rica for 12 years and have obtained very important information about the effects of climate like El Niño. Without long-term studies, it is difficult to understand these natural patterns due to climate. We hope to stay there as long as we can receive funding.
Question: How do you explain the increase in the number of nesting females during the recent season?
Paladino: The most recent increases have been the result of the use of TEDs. They closed some of the long-line fisheries in the Pacific, and also because now we are no longer under the effect of El Niño. That has caused an increase in the number of nesting females and also survival of more females to nest.
Question: Why did you want to be a scientist?
Paladino: I used to love to watch Disney specials as a kid, and also read a book called The Windward Road by Archie Carr. That book inspired me to want to go do sea turtle research. Dr. Carr was a famous naturalist. The book is still available in the library, and although the science is somewhat dated, the book reads like an adventure story.
Question: What are some of the ways that people are helping leatherback turtles?
Paladino: One of the more important ways, other than with the protection from the fisheries, is the protection of beaches, and the prevention of lighting on the beaches and the destruction of beaches for homes. If you want to have a house near the beach, you should have it so the turtles can't see it and have your lights so that they don't shine onto the beach. Laws in Florida and South Carolina and Georgia have been very helpful in permitting turtles to now return to American coastlines. And there's been a lot of nesting on beaches where turtles were rare. That's because we've shut off our lights and protected the beaches from people building on them. Lots of these kids can volunteer with local groups if they live near a beach, to make sure that people turn their lights out at night during the nesting season. Right now it extends on the east coast from March through the end of July.
Question: How fast are sea turtles when they are swimming and when they are on land?
Paladino: Well, on land they don't really move that quickly I'd say they move at the pace of a regular walk. In the ocean, leatherbacks can migrate 70 kilometers a day 1.6 kilometers equals a mile about 45 miles, I guess. They can swim quite fast much faster than the fastest Olympic swimmer.
Question: Does it hurt the turtles to have the PIT tags injected in their shoulder?
Paladino: It would be about the same as them getting a vaccination at the doctor's office. It's like a pin prick. When we give it to them, they're in a trance and laying their eggs, so they really aren't paying attention to it.
Question: Do sea turtles speak in some way to each other?
Paladino: I suspect that they do communicate because they do make verbal noises I've heard them grunt and growl on the beach. They also have ears, which can receive sound, so I suspect they are able to communicate, since they make sounds and have ears to hear sounds. But we don't know how they actually do this.
Question: What should I do if I find a turtle or nest on the beach?
Paladino: The best thing to do is leave the turtle alone and let it make its nest. But, once you know where the nest is, you can protect it by marking it off, and in some communities, they actually put chicken wire over the top, so that raccoons and dogs can't dig up the nest. But for the most part, just leaving it alone and protecting it from people or animals digging it up are the best ways you can help them.
Question: How many leatherback turtles are you currently tracking by satellite, and what are you finding out about them?
Paladino: Currently I only have two that are in the Pacific, and what we find is that they go very great distances. They follow specific routes. When they leave the beaches in Costa Rica, they go directly out to the Galápagos Islands, and then across the equator to Easter Island, and out into the central Pacific.
We suspect they then start to turn around in a circle and head up along the Australian Great Barrier Reef, and head back to Costa Rica, where two to three years later, they will come back and nest again.
Question: How many eggs do turtles lay each year of their life?
Paladino: For leatherbacks, they nest in one season about eight times. They will come out eight times, ten days apart, on the same beach, each time laying about 70 to 80 eggs. So that means they lay about 700 eggs a year. And that means if she comes back every two to three years and lives to be about 40, she'll probably lay around 7,000 eggs. Of those 7,000 eggs that are laid, only about half of them hatch and get into the ocean, so that means about 3,500 of her eggs actually make it into the water. Then, we know the populations are still declining, so that means that not even one of those hatchlings lives to replace her. You would hope at least one would survive and replace mom, but the populations are still declining. So less than one hatchling per turtle is making it.
Question: What do turtles eat?
Paladino: Different turtles eat different things. Leatherbacks are known to eat only jellyfish. Loggerheads, which nest in Florida, eat sponges. Kemp's ridleys, the most endangered turtles, eat shrimp and crabs. Green turtles eat plants they eat turtle grass and algae, and hawksbills eat a variety of invertebrates.
How long can turtles stay under water without taking a breath of air?
Most turtles can stay down up to two hours. However, the average dive is only about 15 to 30 minutes long. They can stay down longer by storing oxygen in their muscles.
Question: Do turtles hibernate?
Paladino: The turtles that are found in freshwater lakes are known to bury themselves in the mud and hibernate. Sea turtles are not known to do this, except for one group found near Baja Mexico that are thought to bury themselves in the mud at the opening of the Gulf of California. But sea turtles don't have to hibernate because they just go to the warmer water, and stay in the tropics during the winter.
Question: How long is this hibernation and what happens to their bodies?
Paladino: That's a project that I've set up to do next year. So, I don't really have an answer we don't know yet if these black turtles in Mexico really do hibernate. So, ask me next year!
Question: How long does it take for the eggs of the sea turtle to hatch?
Paladino: About 45 days. They're buried in the sand and 45 days later, they dig their way up and out. Usually the mothers are gone.
Question: How long does the whole nesting process take?
Paladino: It takes most turtles about an hour to an hour and a half to come out, dig their nest, and get back into the water. So 60 to 90 minutes to accomplish the whole process of coming out of the water, digging the nest, laying the eggs, covering the eggs, and getting back into the water.
Question: What are some of the dangers the hatchlings face when they go from the nest to the sea?
Paladino: There are all forms of predators, ranging from raccoons to coati, coyotes, dogs, ghost crabs, vultures, and night herons will eat the hatchlings. It's estimated that about half of them get eaten as they head to the water on some beaches. So, they have birds, crabs, and mammals that eat them. Once they get into the water, there are lots of fish waiting to eat them, as well as pelicans and bustards [a kind of bird].
Question: Where do baby turtles go their first year of life?
Paladino: That's something we know very little about. Green turtles are known to go out and float in the sargassum floating seaweed. But most of the hatchlings we have no idea where they go or what they do. We only see them when they come back about the size of a dinner plate and start to move into the estuaries along the coastlines and the coral reefs in the tropics.
Question: What do you like about studying the sea?
Paladino: What I like is that it's given me the opportunity to travel around the world to some really beautiful places Central America, South America, South Africa, India, and Australia. And sea turtles really rock!!
Question: Can you tell how polluted the ocean is by how healthy the sea turtles are?
Paladino: Yes, you can. We find plastic bags in the stomachs and intestines of sea turtles that die and wash up on the beach. We also find globules of oil and toxic chemicals in the tissues of dead or dying turtles. So we can tell the effects of pollution.
Question: Why do the turtles lay their eggs at night?
Paladino: It's thought that they lay their eggs at night so they are not seen. In some areas, it also is very hot during the daytime, and the sea turtles would overheat if they came out in the daytime.
So, there are probably two reasons so they can be unobserved and reduce predation, and so they don't overheat. There are some sea turtles, though, that come out in the daytime. And those are found on isolated islands off the coast of Australia those are the flatback sea turtles. They do come out in the daytime, but they also are known to overheat and die if they come out on the wrong tide.
Question: At Playa Grande, how many of the same turtles are returning? Do you have the same turtles still coming from ten years ago?
Paladino: Yes, we do. In any one year, about 25 percent of the females that nest are ones that have been tagged before. And we have some sea turtles that we've seen for 12 years that we've been there.
Question: How do sea turtles react to sunlight?
Paladino: Out in the ocean, they have no problem with daylight. If they're on the beach, in the early morning, they start to head back to the water. And they're usually back in the water before it starts getting hot. In the water, they like to sunbathe and sit up at the surface floating around in the sunshine. I've never seen them wear sunglasses, but I think they like the sun just as much as we do!
Question: Other than to track their movement, what are some other reasons for tagging turtles?
Paladino: I've put data loggers on them that send me information about their heart rate, how deep they dive, where they stay when they go underwater near the surface or closer to the bottom. This kind of information gives us a better idea of what they do when they're out in the ocean. We've also attached video cameras to see what they do when they're in the water. We've seen them interact with each other as well as swim around among fish and in the reefs. The radio tags have allowed us to follow those animals and get back our camera. Another reason we used radio tags was to find out when sea turtles return to an area. In Cocoa Beach, Florida, they wanted to dredge the channel for the big ocean liners to come into the port. But sea turtles would be in the channel and get scooped up and killed by the dredge. We went and collected the sea turtles, took them down to Miami Beach and released them with transmitters. When they came back to the area, we would know it and tell the dredge people to stop.
Question: Do you mark the turtles in some way so you can recognize them?
Paladino: The only mark we use is the PIT tags, which are little tags that we've already talked about. We used to use flipper tags that are external, but we don't use them because they get corroded in the saltwater of the ocean and fall off.
Question: How can the turtles find their way back to the same beach after traveling so far away?
Paladino: Some studies we've just done show that they use the magnetic fields of the earth to navigate. They can sense where they are and have their own internal magnetic compass, which allows them to find out where they are and return to their beach.
Question: How long can they stay out at sea?
Paladino: They stay out at sea their entire lives, except when the females come out to lay their eggs on the beach. So, from the moment they enter the water as hatchlings until they die, they spend their whole lives out in the ocean.
Question: Do turtles look the same now as they did in prehistoric times?
Paladino: The current sea turtles, the hard-shelled ones, the green turtle, the loggerhead, are all about 2 to 6 million years old. The leatherback looks the same as it did 20 million years ago, and looks very much like it's close relative that was around 65 million years ago, at the end of the Age of Dinosaurs. The only difference is that it's about half the size. So, the only sea turtle that looks pretty much the same as it did when dinosaurs were around is the leatherback.
Question: What is the turtles' vision like?
Paladino: It's got very good vision and can see very well, even in the dark. When going down deep, they are able to see their food, and we suspect that they have very good night vision.
Question: What is the most exciting thing about the turtles?
Paladino: What's really exciting is to watch them come out of the water and onto the beach they make you think about the Age of Dinosaurs and what it must have been like to have those giant reptiles walking across the beach digging nests and laying eggs.
Question: What advice do you have for kids who want to become scientists?
Paladino: They should remember that it takes a lot of skills to become a scientist. You have to be good at math, write well, and you must like science, which includes chemistry and physics.
Question: How close to extinction are sea turtles?
Paladino: It's hard to say at this point. Unless we change the way in which we use the oceans, I suspect that not only sea turtles but many marine organisms will become extinct. Sea turtles have been very successful and changed very little for millions of years. It's only been in the last 100 years that they've become endangered. The primary reason is because of their interaction with people. And the only reason they're endangered is because of the way we destroy beaches and wastefully harvest the ocean.
Question: Are there any little-known facts that we should know about sea turtles or any other turtles?
Paladino: One of the interesting facts is that it seems that leatherbacks, the largest sea turtles, seem to be monogamous they only mate with one male. They are also very deep divers. I have recordings of them going down almost a kilometer into the ocean.
Thank you for your efforts!! Is there anything else people can do to make sure turtles live for another 65 million years?
I would say as long as the kids remember to conserve, recycle, and don't buy a house on the beach! Then we should be fine.