UBC PhD candidate T. Todd Jones custom fits a leatherback sea turtle with its own soft harness - photo by Martin Dee UBC Reports | Vol. 53 | No. 4 | Apr. 5, 2007
Harnessing Turtle Power
By Brian Lin
They have been around for more than 100 million years and survived the extinction of the dinosaurs. But human activity and ignorance in the past 50 years has left only 50,000 leatherback sea turtles swimming in our oceans, and as bycatch from fisheries activities, they could be extinct as early as 2015 in the Pacific Ocean.
Now a UBC research biologist may have found the key to saving these quietly charismatic animals from the brink of extinction -- with the help of some rubber hose and fishing line.
At 250-550 kg and about the size of a Volkswagen Beetle®, an adult leatherback turtle is a sight to behold. But few people have the privilege in their lifetime to witness these critically endangered animals due to their enigmatic lifestyle and interactions with fisheries.
“Leatherbacks are oceanic-pelagic animals,”
says T. Todd Jones, a PhD candidate in the Dept. of Zoology, “which means that they are programmed to swim continuously in open waters and are known to swim the entire Pacific Basin to reach their nesting beach -- that’s 13,000 km one way.”
“Unlike the other six species of sea turtles, which forage along the coast or in the reefs, leatherbacks, named after their rubber-textured ‘soft’ shells, have no concept of barriers or boundaries. If you keep them in a tank, they would keep swimming into the walls or dive into the bottom.”
For this reason, researchers have had trouble keeping and studying the turtles to find the secrets to their conservation.
Jones came up with an ingenious -- and deceptively simple -- solution. He custom-fitted hatchlings with harnesses made of soft rubber hoses and attached them to the top of the pool with a fishing string, reminiscent of a Jolly Jumper®. Immersed in filtered seawater heated to a perfect 24 degrees Celsius -- the same temperature as their Subtropical nursing waters -- each leatherback is given its own “infinity pool.”
“As far as they’re concerned, they’re swimming freely in the ocean,” says the Orlando, Florida native, who grew up surfing, snorkeling and fishing the beaches where five species of sea turtles breed and nest.
He also pioneered a recipe to satisfy the leatherbacks’ discriminating appetite. “They eat jellyfish almost exclusively, which is quite different from all other sea turtles,” says Jones. “We blend human grade squid and vitamins with gelatin to create jelly strips that are similar in consistency to jellyfish.”
It takes a half-dozen undergraduate volunteers working seven days a week to clean, prepare and hand-feed the four kg of food that each leatherback eats a day, the equivalent of 20 per cent of its body mass. Volunteers even jiggle the jelly strips underwater to simulate jellyfish movement, which attracts the turtles over to the food.
As a result of these innovations, Jones and his team have achieved the near impossible -- they have raised two healthy leatherbacks from hatchlings since July 2005. At almost two years old and weighing in just under 30 kg, the pair marks the first time more than one leatherback has been raised in captivity, providing crucial comparative data for research and conservation.
Researchers around the world have attempted to raise leatherbacks in captivity since 1936. Only two other researchers have been able to maintain a leatherback for more than a year. In 1988, Vincent Bels, a researcher with the Muséum National d’Histoire Naturelle in France raised a leatherback for more than three years.
By feeding the juvenile leatherbacks to satiation and meticulously keeping track of their diet and growth, Jones has been able to determine a female leatherback’s maximum growth rate. He has found they need 33 million kilojoules (or more than 8 billion calories).
Based on Jones’s findings, leatherbacks could reach sexual maturity in as little as twelve years, compared to 20-30 years for other sea turtles, provided that food sources are abundant. What he has learned about leatherback behaviour, diet and physiology in the past two years will also help create protocols for rehabilitating adult leatherbacks that are caught in fishing nets.
The groundbreaking work earned him the Archie Carr Biology Award, named after the father of sea turtle conservation, at a recent gathering of scientists and conservationists in South Carolina.
“My goal as a scientist is to find out as much I can about these critically endangered animals so we can inform the most effective and appropriate conservation efforts,” says Jones, who has worked with sea turtles for more than a decade.
His message to humans? “We now know the amount of energy it takes for a leatherback to reach adulthood. If we continue to over-use, over-fish and contribute to global warming, there simply won’t be enough resources in the ocean for them to sustain themselves and survive the population decimation due to fisheries practices.
“Everything we do could be affecting a leatherback turtle somewhere,” says Jones.
Quick Facts About Leatherback Sea Turtles
- A sexually mature female leatherback returns to the beach where she was hatched to breed and nest every two to three years. She could lay as many as 65-85 eggs and then disappear into open ocean until she is ready to breed again.
- The hatchlings, small enough to fit in the palm of the hand, must brave predators both on land and at sea, and typically swim non-stop for 36 hours using only nutrients stored in their underbelly. Those who survive are often never seen again until they return as first-time mothers. These are called the “lost years,” because up to now, scientists didn’t know for sure how long it takes for them to become sexually mature or where they went for nursery grounds.
- In the wild, one in 1,000 hatchlings make it to adulthood due to a combination of natural causes and human activities.
- Fisheries bycatch is the number one cause of death for adult leatherbacks in the wild.
- Leatherbacks are the only species of sea turtle with a “soft” shell, which is black with white dots. Each leatherback turtle has a unique pattern, which expands as it grows.
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