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November 28, 2023

Turtles don't recuperate after capture

By MELANIE HSU | April 27, 2012

My turtle-crazy roommate and Parry Gripp's educational video (dude, that's a tortoise!) about how to differentiate between a turtle and tortoise first introduced me to the world of these wonderful reptiles. Turtles are some of the most bada** animals to grace this earth - they outlasted the dinosaurs, braved the mosasaur-infested prehistoric seas and have even made it into fiction, with bubbly characters like Squirtle from Pokemon and Crush from Finding Nemo.
Unfortunately, the survival of some species of turtles is seriously threatened, thanks to human activity. Loggerhead sea turtles, known for their large size and powerful jaws, are among these threatened species.
Once hunted extensively for their meat and eggs, they are now under the protection of international conservation laws. While locals in some countries continue to use loggerback eggs as snacks and aphrodisiacs, the turtles are getting their revenge. Eating turtle eggs can cause serious illness due to toxic metals that build up through bioaccumulation, which occurs when toxins move up the food chain and increase in concentration with each trophic level.
When loggerhead turtles are accidentally captured by humans, the shelled creatures undergo a recovery process according to the severity of their injuries. A team of scientists from Catalonia and the Balearic Islands recently investigated the re-adaptation of these turtles to the environment. According to their results, after a lengthy recovery in rehabilitation centers, the turtles display changes in behavior.
In the study, the researchers placed satellite transmitters onto the shells of 12 healthy, wild loggerhead turtles of the species Caretta caretta, and 6 more on the shells of turtles that had spent a few months in a rehabilitation center in the Balearic Islands.
Lluis Cardona, the principal author of the study and a researcher in the animal biology department in the University of Barcelona, said that the rehabilitating animals were seriously affected when they were captured and had a slow, complicated recovery process.
After they were set free, three of the rehabilitated turtles exhibited changes in behavior. Cardona, who compared these turtles with the 12 controls, found that one turtle died and the other two had trouble swimming - they were very disorientated.
The transmitters sent a signal each time the turtles surfaced to breathe, informing the researchers of the swimming speed and routes followed by the turtles. According to Cardona, the time a turtle spends at the water's surface is very informative about its health. Turtles need to surface regularly in order to breathe and thermoregulate. In addition, the time spent at the surface reflects the turtle's buoyancy control.
While the study's small sample size limits the applicability of results, there is clearly a percentage of animals that do not recover fully after capture or injury. The study raises the question of when recuperating and treating a turtle is worthwhile.
Cardona says that due to limited resources and for the good of the turtle, scientists and veterinarians need to work to establish protocols to determine when a turtle's condition warrants treatment.
The six turtle patients were rehabilitated in the Balearic Islands by the Aspro-Natura Foundation between 2004 and 2007. All of them suffered from major injuries - two were hit by boats, two had stomach and throat injuries from fishing hooks and two sustained flipper injuries from fishing nets.
Most of these animals are caught unintentionally by fishing hooks and trawler or trammel nets. A small percentage collides with boats or gets caught in abandoned nets or plastic.
Fortunately, the number of turtles caught by fishing hooks has fallen, thanks to fishermen moving to deeper waters where fewer turtles reside. However, Cardona warns that the situation remains dire - 90 percent of turtles in the waters around the Balearic Islands hail from the USA. This means that the number of nesting female loggerheads in the country has dropped.

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