Movements of thousands of loggerhead turtles 'predictable'

Jun 23, 2011 by Tamera Jones, PlanetEarth Online
Movements of thousands of loggerhead turtles 'predictable'
Loggerhead turtle.

Satellite tracking technology has revealed in detail for the very first time the annual movements of thousands of loggerhead turtles that live off the east coast of the US.

The ten-year study shows that they go back to the same spots year after year.

This means researchers can now say where, to within a few tens of kilometres, the will turn up at any point during the year.

The is endangered on the IUCN Red List, which means it's at risk of , so the findings will prove invaluable for trying to figure out where to focus efforts to protect the creatures.

'This is a massive help for conservation managers – we can now advise quite precisely where they should direct their conservation effort and funding,' says Dr Lucy Hawkes from Bangor University in Wales, lead author of the study. Hawkes completed the study for her PhD at the University of Exeter.

'This is the first time for part of a population that we've been able to compile all tracking data ever collected to generate a picture of what the whole US population is doing,' she adds.

The study was only possible because of recent advances in technology, an increasingly popular approach among marine biologists and bird experts alike.

'Before this technology, we wouldn't have got anywhere near as much detail using traditional techniques,' says Hawkes.

Biologists have tagged a whole range of migratory creatures, such as the great snipe, the ocean sunfish, and Atlantic leatherback turtles, using GPS and satellite tags or tiny tracking devices called geolocators, to find out more about their migratory routes.

But until now, it was difficult to say if the few published tracks that exist really represent the movements of the whole population.

Loggerhead turtle expert Archie Carr was one of the first to try tracking loggerheads from Florida, taking a decidedly novel approach. He glued huge helium-filled weather balloons to the turtles' shells so that he could follow them from the shore.

Together with colleagues at the University of Exeter and the US, Hawkes tracked 68 adult female loggerhead turtles that live off the east coast of the US between 1998 and 2008. The population runs from North Carolina, to Florida and down to the Gulf Coast and is the world's second largest group of loggerhead turtles.

They found that the turtles tend to stay close to the coast, not venturing beyond the continental shelf. This is because they feed on crabs, lobsters and other crustaceans on the sea floor, which they have to dive down to reach.

Rather than leaving the area during winter, the turtles stay around the coast, but move to warmer waters around Florida.

'This puts them in direct competition with the fishing boats which trawl the bottom of the sea floor,' Hawkes says.

Before this study, researchers couldn't be sure where the turtles went during the winter, so rules surrounding bottom trawling are far less strict during this period, coastal managers didn't think the two coincided.

Hawkes and her colleagues also found that the turtles are 'incredibly predictable,' returning to the same places year after year.

'The big remaining question is whether adult male, juveniles and turtles from the Florida sub-population behave in a similar fashion,' said Dr Brendan Godley from the University of Exeter.

Early results from a study by a different team of scientists suggest they do. If this is true, this predictability means that protecting the world's second largest population of loggerhead turtles shouldn't be too difficult.

The next step for Hawkes would be to combine the data from this study with data on the loggerheads from the Florida beaches to build up a comprehensive picture of the movements of these charismatic .


This story is republished courtesy of Planet Earth online, a free, companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).

Explore further: How ferns adapted to one of Earth's newest and most extreme environments

More information: Lucy A. Hawkes, Matthew J. Witt, Annette C. Broderick, John W. Coker, Michael S. Coyne, Mark Dodd, Michael G. Frick, Matthew H. Godfrey, DuBose B. Griffin, Sally R. Murphy, Thomas M. Murphy, Kris L. Williams, Brendan J. Godley, Home on the range: spatial ecology of loggerhead turtles in Atlantic waters of the USA, Diversity and Distributions, Volume 17, Issue 4, pages 624-640, July 2011, Article first published online: 8 JUN 2011, DOI: 10.1111/j.1472-4642.2011.00768.x

add to favorites email to friend print save as pdf

Related Stories

MasterCard, Zwipe announce fingerprint-sensor card

11 hours ago

On Friday, MasterCard and Oslo, Norway-based Zwipe announced the launch of a contactless payment card featuring an integrated fingerprint sensor. Say goodbye to PINs. This card, they said, is the world's ...

Plastic nanoparticles also harm freshwater organisms

12 hours ago

Organisms can be negatively affected by plastic nanoparticles, not just in the seas and oceans but in freshwater bodies too. These particles slow the growth of algae, cause deformities in water fleas and impede communication ...

Atomic trigger shatters mystery of how glass deforms

12 hours ago

Throw a rock through a window made of silica glass, and the brittle, insulating oxide pane shatters. But whack a golf ball with a club made of metallic glass—a resilient conductor that looks like metal—and the glass not ...

US company sells out of Ebola toys

21 hours ago

They might look tasteless, but satisfied customers dub them cute and adorable. Ebola-themed toys have proved such a hit that one US-based company has sold out.

Recommended for you

Cat dentals fill you with dread?

1 hour ago

A survey published this year found that over 50% of final year veterinary students in the UK do not feel confident either in discussing orodental problems with clients or in performing a detailed examination of the oral cavity ...

User comments : 0