Surveys of Gladstone fishing areas over the past week are indicating a decrease in the number of fish with lesions or cloudy eyes.

General Manager of Habitat and Assessment Dr John Robertson said Fisheries Queensland had conducted a number of supervised fishing trips over the past week and results had been encouraging.

"I wish to make it clear that the closure in Gladstone wasn´t lifted by Fisheries Queensland because there are no sick fish, rather the identified conditions are not a concern," Dr Robertson said.

"The decision to lift the closure was not taken lightly but made following expert advice and scientific test results.

"Scientific testing by the Department of Environment and Resource Management has found little change in water quality in the Harbour over the past year including since dredging began. The exception was following this year´s major flooding events when water salinity decreased.

"The Acting Chief Health Officer has advised that no clear link has been established between the fish and infection cases identified in humans.

"Test results on fish samples have confirmed the symptoms were caused by red-spot disease and a parasite, which do occur in Queensland and are not unexpected given flooding earlier this year and the cool weather.

"The Gladstone Area Water Board has estimated that some 30,000 barramundi washed over the spillway at Awoonga Dam between December 2010 and March 2011 due to overtopping.

"These fish suffered physical stress, which combined with the stress of the relocation, would have also made them susceptible to disease.

"Past experience shows the conditions will naturally pass out of the environment, so they are not a reason to prohibit fishing and are not considered a risk to human health if the appropriate food safety standards are followed.

"A number of fishing trips have been conducted over the past week to assess whether the situation is improving.

"More than 240 fish have now been caught and visually inspected from Gladstone Harbour, the Boyne River, the Calliope River and Awoonga Dam.

"Some have shown skin discolouration, but this could be caused by a number of factors such as the already-identified parasite, net damage or knocks against rocks."

Results so far:

Saltwater catches

• 29 September (night): 8 barramundi caught at Hot Water; 6 of these had skin discolouration
• 3 October (night): 16 barramundi caught at Hamilton Point, 6 barramundi at Tide Island and 5 barramundi at Wit Island; 1 of the barramundi had cloudy eyes (fluke), and 20 had skin discolouration
• 4 October (night): 2 barramundi and 2 thread fin salmon caught at South Trees Inlet; 1 of the barramundi and the threadfin salmon had skin discolouration
• 5 October (night): 61 barramundi caught in the Boyne River, 4 barramundi in the Calliope River, 2 barramundi in the Narrows; of these fish 28 barramundi had cloudy eyes, 24 had skin discolouration and 12 had signs of lesions.
• 6 October (night): 26 barramundi were caught near Turkey´s Beach; of these fish 5 barramundi had cloudy eyes, 3 had skin discolouration and 1 had signs of lesions.

Freshwater catches

• Between 29 September and 6 October: 117 fish were caught in freshwater systems: none exhibited fish health issues other than a minor anchor worm infestation, which is a common parasite that appears all year round.

Dr Robertson said additional laboratory testing of fish samples was also continuing to help Fisheries Queensland assess the extent of affected fish in the Gladstone area.

"New test results have shown that apart from barramundi, no other fin fish had red-spot disease or the parasite," he said.

"Mud crabs and prawns submitted for testing all had evidence of erosion consistent with shell disease that does occur occasionally."

The fish sampling data and new scientific test results will be provided to the scientific panel, which has been tasked with reviewing all available information relating to the health of fish in Gladstone and give independent advice to government.

Dr Robertson said any seafood, regardless of where it was caught or purchased, that showed signs of damage, deterioration or disease should not be eaten.

"Seafood available through retail outlets is from regulated and wide-ranging sources and continues to be safe to purchase and eat," he said.

"The community can be confident of local seafood, as it must meet national standards for suitability and food safety, otherwise severe penalties apply."

Safe Food Production Queensland (SFPQ) will be conducting monitoring activities to ensure requirements are met.

For further information, visit www.qld.gov.au/gladstoneharbour or call Fisheries Queensland on 13 25 23.