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Satellite Tracking

Why did animal X stop transmitting?

Background

Sadly Marloo has been found dead on a remote Northern Territory beach, after an eight month long swim from her natal beach on Gnaraloo Station in Western Australia, where this past nesting season Marloo laid her last and final clutches of eggs.
Feral fox depredation of loggerhead turtle nests is a serious problem at Australian mainland turtle rookeries, but at Gnaraloo because of the ongoing nest protection each season since 2008, it means that her hatchlings have had a better chance to follow in her flipper steps, and return up the Gnaraloo beaches themselves in 25 to 35 years time when they are ready to nest.

Marloo was found in very good condition at Gnaraloo Bay after nesting on 9th December 2015. She was given the flipper tags: front left WB4964, and front right WB4965. A skin biopsy sample AA55056 was taken for later DNA and Stable Isotope Analysis. Her measurements were: CCL 939mm; CCL(Notch) 938mm; CCW 827mm.

She re-nested twice at around 21 day intervals and swam north into Coral Bay on 29th January and out into the Indian Ocean on 2nd February.

From here she was tracked on an unusually long 6 month journey far out into the Indian Ocean and across the Timor Sea, and arrived in Beagle Bay, in the Northern Territory, on 28th July 2016. On 27th August we noticed that she had been 12 hours on a beach on Melville Island, about 75 km from Darwin harbor.

Concerned for Marloo's well-being, on the morning of the 28th we raised the alarm with the Marine Threatened Species Scientist, Marine Ecosystems, Flora and Fauna Division of the NT Department of Land Resource Management who, together with a Parks and Wildlife Commission NT officer, and with the permission of the Tiwi Island landowners, flew out in a helicopter chartered by the Western Australian Department of Parks and Wildlife Marine Sciences Division, to find her dead on the beach.

Marloo was flown back to Darwin on the afternoon of the 28th August and a necropsy was performed by the NT Government's Berrimah Veterinary Laboratory a couple of days later.

Examination of her ovaries showed 2-3mm diameter healed corpusluteum, indicating that she also nested in a prior season more than 2 years ago, and pre-vitellogenic follicles, showing that she would have bred again in a future season. Marloo also had atretic follicles - the resorption of some of this season's mature egg follicles used to fuel longer migration to nesting by marine turtles.

She was found now to be emaciated, and had lost half of her front left flipper sometime after we had tagged her, with that injury now well healed; suggesting that this loss of limb many months before could explain the unusually circuitous and long migration towards her home foraging range - which she may not have yet reached. With more skin biopsy sampling from other turtles over the next few years the Stable Isotope Analysis will help to identify the location of that home range - her intended destination.

http://getregional.com.au/2016/08/nt-helps-wa-unlock-vital-turtle-data/

NT helps WA unlock vital turtle data

Northern Territory Government scientists are helping their Western Australian counterparts researching endangered sea turtles as part of a vital satellite tracking project.

A total of 20 endangered loggerhead sea turtles were released eight months ago from nesting beaches at Gnaraloo Station, Dirk Hartog Island and Muiron Island along the WA coast as a coordinated approach between Gnaraloo Station, WA Parks and Wildlife and independent researcher Aub Strydom.

WA Department of Parks and Wildlife principal scientist, Dr Scott Whiting, said this is the first time turtles at these sites had been tracked.

“Understanding more about important habitat areas will allow potential threats to be identified and managed,” Department of Land Resource Management marine scientist Rachel Groom said.

“Ten turtles were tracked from Gnaraloo Station, the most adventurous of which was a female named Marloo, whose body was found washed up on a Melville Island beach yesterday.”

"We contacted the Department of Land Resource Management who, together with Parks and Wildlife Commission NT officers, organised a search and rescue mission to find Marloo and ultimately recover her body so that a necropsy could be performed in Darwin,” Aub Strydom (Researcher for Gnaraloo Station) said.

“We thank the Tiwi Land Council for promptly providing access permits,” Ms Groom said.

Ms Groom said pathologists from the Department of Primary Industry and Fisheries will perform a necropsy at the Berrimah Veterinary Laboratory tomorrow with the results helping to identify cause of death and add to a growing knowledge base of megafauna nationally.

“Turtles are a great indicator of sea health so the more we learn about them the more we learn about the waters they inhabit.

“The satellite tagging will provide insights into nesting intervals, inter-nesting habitat, migration pathways and important foraging areas.”

  • The presentation of data here does not constitute publication. All data remain copyright of the project partners. Maps or data on this website may not be used or referenced without the explicit written consent of the data owners.
  • For more information please visit the project website.
  • This map connects positions generated by the ARGOS system designated as location class (lc) '3', '2', '1', '0', 'A', 'B'. Locations that have been "filtered" are displayed as small red dots.
  • This maps also shows locations of class 'A' as small black dots which are not connected by a route line.
  • Bathymetry layers are derived from the GEBCO One Minute Grid.
  • Sea surface temperature and chlorophyll are derived from NASA's Ocean Color data.
  • Ocean currents and sea surface heights are derived from AVISO's Ssalto/Duacs Gridded Absolute Dynamic Topography & absolute geostrophic velocities data.

SEATURTLE.ORG collaborates with Argos to help scientists and conservationists manage and analyse their valuable animal tracking data.

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