5 days ago
Salmon company Huon used tonne of antibiotics in bacterial outbreak, EPA report finds
Samples of wild fish caught near a Huon Aquaculture lease in February were found to have antibiotic residue levels up to a dozen times higher than the threshold for commercially sold salmon, according to an Environment Protection Authority (EPA) report.
The interim report monitoring Huon's antibiotic use was completed by environmental consultants Aquenal.
According to the report, 1,133 kilograms of the antibiotic Oxytetracycline (OCT) was administered via fish feed at Huon's Zuidpool lease between February 13 and February 26 this year.
In February, a mass mortality event caused by the bacterial pathogen Piscirikettsia salmonis devastated salmon farms in the D'Entrecasteaux Channel, south of Hobart.
Between January and March, the death of more than 13,500 tonnes of salmon was reported to the EPA by the three major salmon companies operating in the state.
By late February, Huon's Zuidpool lease had begun to draw public and media attention after the Bob Brown Foundation released drone footage showing workers at the lease putting live salmon into tubs along with dead stock.
Oily globules made of salmon fat began washing up along beaches on the channel, which were found to contain low levels of antibiotics.
According to the Australian New Zealand Food Standard Code, salmon destined for sale must comply with an antibiotic maximum residue limit (MLT) of 0.2 milligrams per kilogram.
The report said eight samples of wild fish were taken in the Zuidpool North lease, with three samples — all blue mackerel — testing above the reporting threshold.
It found one sample site with wild fish showing "relatively high" antibiotic residue levels of up to 2.4 milligrams per kilogram, or 12 times higher than the maximum antibiotic threshold for commercially sold salmon.
In a statement, Tasmanian Public Health Director Mark Veitch said the results were consistent with estimates used in a Food Safety Australia New Zealand (FSANZ) risk assessment.
"These samples were collected in late February 2025, in the days after the period of [antibiotic] dosing ended, when antibiotic residue was most likely to be present in fish and the environment."
The report also tested at Zuidpool South, with no samples returning antibiotic residue levels above the limit of reporting.
Samples were also taken at five locations several kilometres from the Zuidpool salmon pens.
One of those sites, Ventenat Point on Bruny Island, recorded noticeably elevated antibiotic levels in blue mackerel that was sampled.
Verona Sands, Jetty and Conleys Beach on Bruny Island, and Roaring Beach near Surveyors Bay were also sampled for antibiotic levels.
Aquenal said the results of those surveys will be released "in subsequent reports".
The EPA will release a final report with all sample results after the monitoring program finishes.
It raised concerns that prolonged exposure to antibiotic treatment could result in resistant bacterial strainers that were more difficult to treat.
This year the EPA would not disclose how much antibiotic was being used by Huon, citing commercial in confidence.
"If individuals are concerned at all about potentially having antibiotics in wild fish, then of course they can choose to fish further away from the [affected] lease," former EPA Tasmania director Wes Ford said at the time.
Antibiotics have been commonly used by salmon companies to treat bacterial diseases.
However, the EPA said antibiotic treatment has declined since 2009 due to the development of vaccines.
In 2022, Tassal used 675 kilograms of the same antibiotic to treat a vibrio outbreak at its Sheppards lease off the coast of Coningham.
Three flathead caught 2 kilometres from the lease were also found to contain more than the reportable threshold of antibiotics in their flesh that same year.
