A MAJOR public heath scare has emerged in Gladstone, with the State Government announcing it will close up to 500sq km of the central Queensland coast to fishing and warning that seafood should not be handled or eaten.

Barramundi, blue salmon, whiting and fingermark bream have been found with sores, rashes and infected eyes, some possibly blind.

It follows the death of more than 100 turtles since the start of the year near Gladstone and fears that fish are being impacted by pollution and the release of acid sulphate from major dredging and coastal works in and around the highly industrialised city.

Gladstone Fish Market owner Ted Whittingham said it was a disgrace the Government had been so slow to act, when fishermen had been warning about problems since October.

Problems had increased over the past four weeks, with about 30 per cent of the catch infected.

"We've been asking for action for six months," Mr Whittingham said. "In the end, the fishing fraternity gave the Government 24 hours to say whether these fish were fit for consumption, and that's how we got to this situation.

"We've even had crabbers getting sores on their arms from pulling pots out of the water."

A Fisheries Queensland spokesman said the department first received reports of fish with milky eyes in early August. Fisheries put a process in place to pay for the transport of fish.

"The first samples only arrived in the past fortnight and have since been undergoing testing," he said. "We expect to start receiving results next week."

Mr Whittingham said ill fish did not go to retail sale as far as he knew.

Economic Development Department director-general Ian Fletcher said yesterday Gladstone Harbour would be closed to fishing to protect public health while the situation was assessed.

Safe Food Production Queensland principal policy officer David Wilkinson said the closure would ensure fish potentially unsuitable for consumption would not enter the food chain.

Queensland Health acting chief health officer Michael Cleary said seafood that showed signs of damage, deterioration or disease should not be handled or eaten.

"Anyone who has concerns about their health which might be attributed to the handling or consumption of seafood from the local area should seek medical advice," Dr Cleary said.

Since May, the Gladstone Ports Corporation has dredged about 700,000 cubic metres of a proposed 25 million-cubic-metre project over three years.

It says there is no link between its work and the fish and that they have previously conducted far bigger dredging programs without any health issues.

Greens spokeswoman Libby Connors said she saw black sludge being dredged out of the harbour in July.

"The sea bed mud was so black it looked like coal dust had settled in that part of the harbour and was being stirred up by the process," Dr Connors said.

Multiple factors could be involved, she said, from the increase in fresh water after the January floods through to mangrove and vegetation clearing on Curtis Island as well as increased dredging for port expansions.

Dr Connors said Federal Environment Minister Tony Burke had to reject the fourth liquefied natural gas plant for the region.

An Environment Department spokesman said it was premature to speculate on reasons for the problem.

The department's chief scientist Col Limpus last week put the high numbers of turtle deaths down to the loss of seagrass meadows after two big wet seasons.

This also has occurred in Moreton Bay and particularly in the Cairns to Townsville region.

Fisheries Minister Craig Wallace said the port was working with the Environment Department to ensure all conditions of the dredging project were met.

Independent water quality tests had found no impact from dredging which would affect fish.

Originally published as Sick seafood forces fishing ban