Sea Turtles Followed Through Their Hidden Travels
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Bond, a green turtle from Dry Tortugas: CREDIT: Kristen Hart. |
Although he doesn't know it, a green turtle named "Bond" is bringing scientists along on his hidden travels in the Gulf of Mexico.
Last August, Bond was tagged with a satellite transmitter and other tracking devices. Now that he's back in the waters around Dry Tortugas National Park, 70 miles (113 kilometers) west of Key West, Fla., he's updating scientists by the day on his whereabouts. Marine biologists are following Bond and 27 other tagged sea turtles to learn how to protect these threatened and endangered species .
The sea turtles — green turtles, loggerheads and hawksbills — may spend the majority of their lives away from the federally-protected beaches of Dry Tortugas and away from the eyes of scientists. Tracking the turtles will reveal where they spend their days so that habitat managers can protect these areas.
"When they're on land we only get such a brief period with them, and then we don't get to see them for the rest of their lives," said research ecologist Kristen Hart of the U.S. Geological Survey. Hart said she and her colleagues are watching the sea turtles as if they were following their own children.
Rodeo-tagging
Following the turtles requires tagging them with monitors, but attaching a tag to a sea turtle is harder than it sounds. One page from the researchers' playbook is called the "rodeo-capture."
Aboard the 22-foot- (7-meter-) long whaler boat Caretta caretta (the loggerhead's Latin name), researchers lean over the ship's edge, holding only a post for balance, and scout for turtles.
"You have to have your eyes on the water at all times," Hart said.
The ship will coast alongside the left side of a turtle, which may be swimming at 5 mph (8 kph). When the turtle comes up for air, two divers decked out in snorkels and gloves plunge into the water. They grab the turtle and point the head skyward.
Two of the stronger scientists on the boat then lift the turtle, which can weigh up to 400 pounds (181 kilograms), onto a foam pad on the boat's deck. The research team then takes measurements and blood samples, affixes tags and sends the creatures back on their way. [See how the scientists tag the turtles .]
To track it, a $1,350-dollar satellite transmitter is glued to the turtle's shell. The tags are no more than 5 percent of a turtle's body weight, so they don't know they are there.
How long the tags last varies depending on where the turtles go and what they do. Rubbing against reefs and rocks can dislodge a tag. Barnacles can grow on the antenna and disrupt data transmission.
However, one turtle named Bertha — the first turtle that Hart tagged on this project — has been transmitting data for 760 days thanks to new battery-saving technology. Typically the tags would fall off after a year as the battery dies.
Travel tracking
Researchers have mapped the turtles' movements to see where they spend their days between nesting seasons. Sea turtles may lollygag on land, but they are quite adventurous underwater.
The rambling sea turtle Bertha left East Key beach in the Dry Tortugas in May of 2008 and traveled all the way to the Bahamas, where she was last spotted in late June 2010. Hart tracked one turtle to Cuba, and saw evidence that it was harvested by fishermen, which often happens when sea turtles get snared in fishing lines.
If the research team can find an area that sea turtles hang out in, and also nest, then this place might be a real hot spot where human activity should be limited, Hart said.
"We're not trying to exclude fishermen but there are restrictions that make sense to afford them additional protection," Hart said.
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