The death toll of the world's largest sea turtles continues to climb on the NSW Central Coast, with a sixth leatherback washing ashore and another found entangled in a shark net this week.
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The latest leatherback was found at Forresters Beach on Wednesday.
It was removed for investigation and sampling.
It is the sixth leatherback to be found dead on a Central Coast beach within about a month, according to NSW National Parks and Wildlife Service (NPWS).
NPWS said between March 18 and April 10, five turtles were found on Little, North Shelly, Avoca and Birdie Beaches.
The founder of Australian Seabird and Turtle Rescue Central Coast, Cathy Gilmore, said it was alarming.
"It's really a mystery as to what's going on."
Recent storms partly to blame
An NPWS spokesperson said the deaths were under investigation by the Australian Registry of Wildlife Health and the Australian Museum.
NPWS has previously said warm sea temperatures and recent storms may have played a part in the turtles' deaths.
University of Newcastle's marine ecologist Vincent Raoult agreed.
"We've had some unusually warm waters coming down as a result of climate change and the strengthening of the East Australian Current in addition to these really big storms," Dr Raoult said.
He said storms could confuse marine life where they could drift into places they did not usually swim or that had lots of plastics.
"It can be that they've ended up in waters that they're unfamiliar with that are too cold and gotten disoriented," Dr Raoult said.
Turtle trapped in shark net
On Wednesday morning, a turtle was also caught in a shark net at Macmasters Beach.
The Department of Primary Industries said the 1.8-metre-long turtle was entangled for just under two hours before it was released and swam off.
Ms Gilmore said she would not be surprised if some of the deaths were caused by entanglements.
"The leatherback turtle at Forresters Beach did seem to be dead for some time, so we do not believe it was the same turtle," she said.
"We need to stay alert now.
"We would prefer a turtle come into care, but this is a leatherback and we don't have the facilities for a huge turtle like that."
