Loggerhead turtles take 45 years to grow up

Loggerhead turtle (c) Gail Schofield The new estimate shows how long it will take turtle conservation efforts to yield results

Related Stories

Loggerhead turtles take almost half a century to reach maturity, say scientists.

A female turtle, the researchers report in the journal Functional Ecology, will not start to lay eggs until she is 45.

This estimate, based on examination of several decades of data on the turtles' growth, has implications for conservation efforts.

It reveals how long it takes for turtles hatched at a protected nesting site to return to that site to breed.

Start Quote

Previous estimates of their age at maturity are all over the place - spanning from 10 years to 35 years”

End Quote Prof Graeme Hays Swansea University

Prof Graeme Hays from the University of Swansea, one of the authors of the study, explained how reaching maturity so slowly meant that the turtle population was "less resilient" than previously thought.

"The longer an animal takes to reach maturity, the more vulnerable the population is to [man-made] causes of mortality," said Prof Hays.

This, he explained, was because there was a much higher chance of an individual animal being killed - for example, by being deliberately or accidentally caught in a fishing net - before it had been able to "replace itself" by breeding.

It is, however, extremely difficult to follow the life cycle of a sea turtle. These long-lived marine reptiles are impossible track as they drift through thousands of kilometres of ocean, spending the vast majority of their time underwater.

Loggerhead turtle hatchlings (c) Gail Schofield The team estimated the loggerheads' growth rate by collating measurements of newly hatched turtles

"You can't follow one individual throughout its life," Prof Hays explained.

"So previous estimates of their age at maturity are all over the place - spanning from 10 years to 35 years. It was impossible to get some sort of consensus."

To overcome this problem, the researcher and his colleagues embarked on a three-part data trawl.

To estimate the growth rate of newly hatched turtles, the team examined measurements of hatchlings at a nesting site in Florida and compared these with the sizes of the same turtles when they had drifted across to the Azores islands in the middle of the North Atlantic.

This journey - drifting several thousand kilometres on the currents - takes approximately 450 days. The scientists were able to see from the data they examined how much the turtles grew during that time.

The team also used many hundreds of measurements made by scientists who had captured, marked and recaptured individual loggerhead turtles. Using these figures, they were able to chart the animals' growth rate.

All of this data enabled the researchers to use the size of mature loggerhead turtle mothers - measured at several well-studied nesting sites - to estimate their ages.

Bryan Wallace, science adviser for Conservation International's Sea Turtle Flagship Program, said that knowing how long it took turtles to grow up gave "a better idea of how long conservation efforts should be maintained on nesting beaches before we can expect to literally see the results".

Dr Wallace told BBC Nature: "These estimates reinforce that animals like sea turtles take a very long time to recover from human-caused population declines.

"So conservation efforts must be appropriately targeted to address the most important threats, and they must be maintained for decades to ensure success."

Follow @BBCNature on Twitter

More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites

More from nature

  • Cardinal fish and ostracodFish filmed spitting 'fireworks'

    Film crew captures ostracods' spectacular defensive lightshow that makes predatory fish spit them out.

  • Arapaima'Locally extinct'

    A giant fish which used to dominate the Amazon river is now absent in many areas


  • DragonflyRapid reactions

    Dragonfly's super quick reactions recorded in slow motion by BBC film-makers


  • Wingless adult male of the midge Belgica antarcticaExtreme survivor

    Antarctic midge's small genome may be an adaptation to its extreme environment


  • Myotis midastactus specimen (previously identified as Myotis simus)Golden discovery

    A bat from Bolivia is described as a new species by scientists


  • Dinosaurs 'shrank' to become birds

    Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, new research shows.

  • Would we starve without bees?

    Honey bees are under threat, and as pollination significantly contributes to the food we eat, what would we do without them?

  • Eggshells may act like 'sunblock'

    Birds' eggs show adaptations in pigment concentration and thickness to allow the right amount of sun for embryos, scientists say.

  • Female shrimps are more aggressive

    Female snapping shrimps are more aggressive than males when defending their territories despite their smaller claw size, a study shows.

BBC iWonder

  • Honey bee close-upInsect intelligence

    Are honey bees as smart as your sat nav?

  • Tyrannosaurus rex skull (c) Mark Williamson / Science Photo LibraryDinosaur dynasty

    One group of dinosaurs survived and their descendants can be seen all around us today


  • Brown rat cluse upRise of the rodent

    Reports of giant, 'super rats' are filling the headlines. But why are we being overrun by rats?


  • Cuckoo portraitHoliday hotspot

    What makes the UK such an attractive destination for visiting wildlife?


There have been 75 solar eclipses and 167 major volcanic eruptions in my lifetime

Nicole Malliotakis on Twitter comments on the events that have happened since she was born by using our personalised Your Life on Earth interactive infographic.

Get Inspired

ACTIVITY FINDER

More Nature Activities >

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.