Rare turtles cause a stir

A leatherback turtle in the Bay of Plenty. Photos: Nathan Pettigrew

A sighting of three leatherback turtles from the wildlife cruise boat Bay Explorer is causing a re-think about the species says skipper Brandon Stone.

'It's extremely rare and it changes a lot of theories about the species in the area as well,” says Brandon.

'They are pretty much seen as a solo animal or there's an incidental drift theory that they come into the area.

'But these animals were definitely navigating and travelling as a unit.”

The three turtles, one larger and two smaller were seen feeding within 100m of each other.

They eat jelly fish, not the little white jelly fish seen along the shore but big purple ones, more an oceanic species says Brandon.

He says it's also why they have seen sunfish this summer in spite of the water temperatures not being up to tropical standards. Sunfish also eat jellyfish.

Leatherback Sea Turtle's are thought to live about 45 years in the wild and can weigh about a tonne.

While all other sea turtles have hard, bony shells, the carapace of the leatherback is somewhat flexible and almost rubbery to the touch. Ridges along the carapace help give it a more hydrodynamic structure. Leatherbacks can dive to depths of 1,280 meters —deeper than any other turtle—and can stay down for up to 85 minutes

As a species Dermochelys coriacea is a reptile as old as the dinosaurs. There were leatherback turtles in earths' seas when Tyrannosaurus rex was king of the land lizards more than 60 million years ago.

Leatherbacks have the widest global distribution of all reptile species, and possibly of any vertebrate – according the National Geographic.

Adult leatherbacks traverse as far north as Canada and Norway and as far south as New Zealand and South America. Unlike their reptilian relatives, leatherbacks are able to maintain warm body temperatures in cold water by using a unique set of adaptations that allows them to both generate and retain body heat. These adaptations include large body size, changes in swimming activity and blood flow, and a thick layer of fat.

Once prevalent in every ocean except the Arctic and Antarctic, the leatherback population is rapidly declining in many parts of the world.

Many leatherbacks meet an early end due to human activity. It is estimated that only about one in a thousand leatherback hatchlings survive to adulthood. Eggs are often taken by humans from nests to be consumed for subsistence or as aphrodisiacs. Many leatherbacks fall victim to fishing lines and nets, or are struck by boats. Leatherbacks also can die if they ingest floating plastic debris mistaken for their favorite food: jellyfish. Some individuals have been found to have almost five kilograms of plastic in their stomachs.

The species is endangered with the Pacific population declining at an alarming rate due to egg harvest, fishery bycatch, coastal development, and highly variable food availability. Some Pacific populations have disappeared entirely from certain areas, such as Malaysia.

Brandon says the Bay Explorer was 'quite a way out' when they found the turtles. On board were tourists from the North Shore, Germany and Asia.

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1 comment

Cool

Posted on 15-01-2017 18:59 | By overit

This is great news, I hope these creatures form a population around our waters.


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