Scientists probe dead turtle mystery

By Anna-Marie Lever
Science and Nature reporter, BBC News

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Rob Deaville performs a turtle post-mortem

"There have been an unprecedented number of loggerhead turtle strandings this year; 18 have been recorded so far on the UK coast," Rod Penrose explains.

Marine Environmental Monitoring has received several calls from coastguards and walkers along the South Coast reporting turtles being washed up.

Mr Penrose, the UK and the Irish Republic's turtle strandings coordinator, says: "Strandings have been reported from Cornwall to Wales and islands off Scotland."

Loggerheads (Caretta caretta) are categorised as endangered on the internationally recognised Red List of Threatened Species. They breed on the northwest Atlantic, Gulf of Mexico and Caribbean coasts.

Unravelling the mystery

Determining why these rare turtles are arriving on UK shores can be very difficult unless a post-mortem is undertaken.

"We carry out a standard series of observations and tests," says Mr Rob Deaville, a cetacean expert at the Zoological Society of London (ZSL).

He adds: "An external examination will reveal if the animal has suffered any trauma or damage in the past.

"A depleted fat layer and the wasting away of muscle can suggest starvation as a result of cold-shock.

"Bacteriology tests can help to determine if the turtle is suffering from disease."

The Cetacean Strandings Investigation Programme (CSIP), coordinated by ZSL and funded by Defra, has conducted 22 marine turtle post-mortems since 2001.

Struggle to survive

Mr Deaville says: "Causes of death have predominantly been a result of 'cold shock'.

"Hard-shell species of marine turtle, like loggerheads, are normally found in warmer waters south of the UK and are unable to raise their body temperature in order to survive in cold UK waters.

"The turtle can experience cold shock because of the colder water, become lethargic and unable to feed and eventually starve to death.

With some scientists forecasting a greater number of storms in the future, due to climate change, Mr Deaville warns: "Extreme weather conditions could lead to an increase in turtle strandings on the coast of the UK."

Hard-shelled marine turtles get cold in UK waters and struggle to survive

Plastic bag and balloon ingestion have also been found as the cause of death in a small number of cases. Turtles swallow plastics after mistaking them for jellyfish, one of their staple foods.

As well as a series of tests, a number of measurements and photos are taken at post-mortem, which are archived.

Mr Deaville adds: "Stranding events can help us increase our knowledge of marine animals which are usually so hard to study in the wild.

"Any opportunity where you can study them further allows us to gain a much better picture of the animal's biology.

"It can help us to understand the species as a whole and contributes to their conservation in the long term."

Lucky loggerheads

Of the 18 stranded loggerheads recorded this year, five were found alive, but only two have survived.

"James", named after his scientific code number 2008/007 - being the seventh loggerhead found this year - and "Dink", are currently at home at Newquay's Blue Reef Aquarium. They were stranded one week apart in January.

UK TURTLE STRANDINGS 2008 Loggerhead: 18 Kemps Ridley: 2 Leatherback: 2

"When James first arrived he was at death's door. He was lethargic, dehydrated, covered in oil and very cold. Dink, being smaller, was more vulnerable but amazingly in better health than James," says Mr David Waines, manager at Newquay's Blue Reef Aquarium.

He continues: "We warmed them up steadily but slowly, increasing the water temperature of their tanks from 10C, the temperature of UK sea in January, to their preferred temperature of 25C.

"We scrubbed their shells daily and applied antiseptic gel to infected lesions. James was put on a course of antibiotics and anti-fungals to cure infection.

"We were overjoyed when several weeks later they started eating for themselves and putting on weight - we knew they were on the road to recovery."

Homecoming

Dink and James have made such good progress they are being prepared to return to the wild. They fly to the Canary Islands in late June.

Lucky loggerheads, James and Dink survived their strandings

Mr Waines says: "It can be quite a long journey, especially as marine turtles are not used to air-travel, but they will have reached peak condition and we are making sure the operation will run as smoothly as possible.

"Once they reach the turtle rehabilitation centre in Gran Canaria they will be checked over and hopefully released within 24 hours.

"We will also microchip them, so if they are ever found by scientists again, their history will be known."

He adds: "It will be sad to see them go; they will be greatly missed, but it is great to know they are returning to the wild."

Dink's and James' success story started when their stranding was reported to Marine Environmental Monitoring.

They ask people to be on the lookout: "If you come across a stranded animal, please report it to the strandings network as soon as possible. Marine turtles are a protected species in Britain and shells must not be kept.

"A turtle may appear dead as its metabolism has slowed down due to the cold water and may not move at all, but it may still be alive."