Mystery surrounds the reasons behind dozens of dead sharks that have been washed up onto a Queensland beach.

Construction site manager Lance Payne made the grim finds over two visits to the Louisa Creek Beach, on Australia's east coast.

The 54-year-old said he said he found an "alarming number" of carcasses during his first visit in November, with at least eight more turning up on Sunday (3 December).

Payne, a keen conservationist, first came across the dead animals in mid-November. He was clearing the beach of coal, which he blames on production at a nearby local coal mine.

"They [the sharks] were strewn all over the beach... it was really alarming," Payne told Yahoo7.

He added on Facebook: "The sharks seamed in quite good health with no evident cause of death [and] the corpses had not been predated on by other fish."

But at the weekend the resident of the nearby city of Mackay returned to find more carcasses.

Construction site manager Lance Payne said he has found an “alarming number” of carcasses on the beach in November and this month
Construction site manager Lance Payne said he has found an “alarming number” of carcasses on the beach in November and this month Lance Payne/Facebook

Payne said on Facebook: "This time there was a mix of species, including a baby hammerhead shark. I was so disappointed to see it killed at such a young age."

The environmentalist initially thought the animals had been killed to make the Chinese delicacy shark fin soup.

But since then he thinks the creatures simply might have been swept up by commercial fishing ships.

He said: "They [the sharks] end up as waste in fishing nets before being flung back into the water dead."

Payne also points to the effect of coal in the water, which he says reduces oxygen levels in the surrounding sea, as a reason for the death of the beasts.

"Why are people killing these young sharks? Its just not right," said Payne.

A number of dead sharks being washed up onto the Louisa Creek Beach, on Australia’s east coast
A number of dead sharks being washed up onto the Louisa Creek Beach, on Australia’s east coast Lance Payne/Facebook