The NSW Department of Primary Industries (DPI) Fisheries continues to investigate fish deaths at Swan Lake, near Cudmirrah on the NSW South Coast.
Reports indicate thousands of dead fish, mostly bream, have been affected, whilst other species are also showing signs of distress in some areas of the lake.
DPI Deputy Director General Sean Sloan said investigations into the cause of the fish deaths are on-going.
“Water quality testing has shown that dissolved oxygen levels were critically low at the inlet to Swan Lake in the morning and this is suspected to have contributed to the fish deaths,” Mr Sloan said.
“However, we are also conducting investigations as part of standard processes to rule out the possibility of disease.
“We recommend people do not consume or handle fish showing signs of poor health (such as cloudy eyes, ulceration, fish schooling in the shallows or swimming slowly), and to clean, wash and cook thoroughly any fish caught for consumption in other areas of the lake during this time.
Mr Sloan said in this instance, management options are limited as fish relocations are not recommended as it may further stress fish, reducing the likelihood of survival in the ocean, whilst also potentially risking further spread of any potential disease or secondary infections.
“Investigations into the water quality and algal community of Swan Lake are also being undertaken, with input from Shoalhaven City Council and Department Planning and Environment.
“The quality of the water in the coastal lakes can change over time from natural environmental processes, such as strong winds and rainfall, and this can sometimes result in fish deaths like we are seeing in Swan Lake,” Mr Sloan said.
The management of coastal lakes is complex, involving a range of agencies and options to ensure any actions avoid impacts, whilst trying to reduce risks to fish and other aquatic animals, as well as people using the lakes.
“It’s also not recommended that the lake be opened at this time as it may further exacerbate fish kill impacts and risks throughout a larger area of Swan Lake,” Mr Sloan added.
“Opening coastal lakes at unfavorable times can transfer oxygenated water away from the system further reducing water quality, whilst also potentially draining the lake and creating ineffective openings that close rapidly and create larger sand bars and future blockages.”
Shoalhaven City Council operates an Entrance Management Policy for Swan Lake, and other coastal lakes in the region, with licenses from various State Government Agencies, with unauthorised openings prohibited.
All fish and seafood products available in seafood outlets is safe to eat and is not impacted by these events. Seafood consumers can feel confident in purchasing seafood from all seafood outlets because the NSW Food Authority has processes in place to ensure food safety across NSW.
For any further information on the management of Swan Lake please contact Shoalhaven City Council at 1300 293 111.
Community members are encouraged to report any fish deaths or observations through the Fishers Watch phoneline on 1800 043 536.
