Article-Antibiotics from fish farm in Derwent River
Hobart Mercury | Tuesday July 7, 2026
Antibiotics from fish farm in Derwent River
Elise Kaine
Calls are growing for freshwater salmon farms to be legislated as strictly as marine operations following a new report that found antibiotic residue in wild fish, sediment, and the Derwent River after a mass mortality event at a salmon hatchery earlier this year.
The report revealed that in January, Huon Aquaculture applied 51.7kg of the broadspectrum antibiotic oxytetracycline (OTC) at its Meadowbank Hatchery, about 20km upstream from New Norfolk on the Derwent River.
The 20-day antibiotic administration was prompted by a sudden 5°C spike in water temperature, which led to an outbreak of bacterial enteritis and elevated fish mortalities.
The Meadowbank Hatchery OTC Residue Monitoring Interim Report indicated the treatment commenced on January 21, 2026.
The public became aware of the antibiotic use through a media report in February.
Huon Aquaculture subsequently posted a statement on Facebook on February 10, saying it had voluntarily informed the Environment Protection Agency (EPA) about the treatment, despite no legal obligation to do so.
Independent MLC Meg Webb said the incident highlighted the need for transparency in the industry, including mandatory antibiotic monitoring in hatcheries.
She said any industry operating in public waterways, especially those connected to drinking water, should be “ultra-transparent”.
Ms Webb said it was problematic that Tasmanian residents – particularly those downstream from the hatchery – only learnt months later about antibiotic residue in the waterway, sediment and native fish.
She called for the EPA to make full and timely disclosure of antibiotic use and subsequent monitoring data a mandatory licensing requirement for freshwater fisheries, adding that the interim report raised further questions about the regulatory system for finfish farms in Tasmania’s fresh waterways.
An EPA spokeswoman said the agency had “committed to inform the public via live maps on its website for any future antibiotic treatment events and will continue to publish reports for each antibiotic treatment after completion of the required therapeutant residue monitoring program”.
She said the variation of environmental licences for inland farms was currently underway and expected by September.
Environment Tasmania campaigner Jess Coughlan said mortality events triggered by increased water temperatures would become more common.
She urged the government to legislate against “flowthrough” hatcheries and mandate the use of modern Recirculating Aquaculture Systems, which reuse up to 98 per cent of water.
Ms Coughlan said environmental licences for any industry should demand zero environmental impact.
If an industry could not operate without polluting drinking water and public resources, it should not be permitted in the state.
She noted OTC was listed by the World Health Organisation as an antibiotic of significance to human health.
The interim monitoring report revealed that oxytetracycline residues exceeding the standard limit of reporting were detected across multiple environmental samples for weeks following the antibiotic treatments.
In the surrounding water and sediment, elevated antibiotic levels above the reporting limit were recorded up to six weeks and 12 weeks post-treatment, respectively.
Testing of wild fish caught downstream of the hatchery showed residue levels exceeding the limit in native short-finned eels on both day seven and day 21 after the application had concluded.
The EPA spokeswoman said the detected antibiotic residues do not indicate environmental harm and “the Director of Public Health has outlined that the monitoring results for Meadowbank indicated that the use of OTC in January and February 2026 did not pose a risk to human health”.
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