Tasmania’s largest salmon company, Tassal, sought to block the release of monitoring reports submitted to the state’s Environment Protection Agency (EPA) after using more than two tonnes of antibiotics at two of its fish farms.
In early January 2022, Tassal and Huon Aquaculture reported outbreaks of vibrio, a bacterium the Tasmanian Salmonid Growers Association says can cause an infection with a “high mortality rate”.
To treat the outbreak, Tassal used 675kg of a broad-spectrum antibiotic, oxytetracycline, at its Sheppards lease near Coningham, just south of Hobart. An internal memo obtained under right to information laws reveals that EPA staff reported that there was a “sticking point” in discussions with Tassal, which dated back to the company’s argument that the monitoring report on a previous use of antibiotics in 2020 should not be made public.
The January 2022 memo to the EPA director and chief executive, Wes Ford, revealed that there had been a long-running standoff with Tassal over the public release of a September 2020 report on the use of 1.3 tonnes of oxytetracycline at the controversial Okehampton Bay lease near Triabunna.
According to the EPA, Tassal provided “a number of legal reasons” why the report should not be released in full, including that the information should be considered commercial-in-confidence. The company objected to the publication of details about how much antibiotic was used and the number of salmon cages that were treated.
The EPA informed Tassal of its intention to publish the report on 16 November 2020 unless it could “provide further justification why not”. But the report remained buried until July 2022, when it was published on the EPA website without public notification.
An EPA spokesperson confirmed the agency had been “in dispute” with Tassal “over material contained in the report, and whether or not it should be published”. They said the government amended the Environmental Management and Pollution Control Act in December 2022 to allow the EPA director to release and publish “relevant environmental information”.
A table in one of the documents reveals the Tasmanian salmon industry has used more than 31.4 tonnes of antibiotics in marine leases since 2003.
Sheenagh Neill, a spokesperson for Marine Protection Tasmania, said the use of antibiotics appeared to be increasing, which was “extremely disappointing, given that vaccines are available”.
“The salmon producers need to lift their game.
“Tassal has very good reasons for wanting to keep the public in the dark about their poor animal husbandry practices and their dumping of tonnes of antibiotics into our public waterways: it makes them look bad. I’m pleased that the EPA did not pander to Tassal’s wishes.”
Tassal says on its website that before being slaughtered, salmon treated with antibiotics “must go through a lengthy withdrawal period, as required by the authorities to ensure no residue”. The regulatory withdrawal standard for salmon for the domestic market is 1,000 degree days, a cumulative tally based on water temperature. (If the water temperature is steady at 16C, the 1,000 degree days threshold is reached on the 63rd day.)
“Why is there a 1,000 degree days clearance required for salmon, yet any person fishing for flathead has no idea about possible antibiotic residues in the fish they catch in the ‘wild’?” Neill asked.
The World Health Organization (WHO) has warned that misuse of antibiotics is accelerating the development of antibiotic-resistant organisms. It describes this as “one of the biggest threats to global health”. The WHO has recommended the vaccination of farmed animals as one way to reduce the overuse of antibiotics.
The EPA and Huon Aquaculture agreed on the requirements for an antibiotic residue monitoring report after the company used 400kg of trimethoprim to treat salmon for vibrio at its East of Yellow Bluff lease off the coast of Bruny Island.
The company acknowledged the salmon were unvaccinated, but told the EPA in an email they would be in future “to prevent recurrence of this situation”.
Huon Aquaculture did not respond to questions about whether this change has been implemented. Tassal did not respond when asked if the salmon at the Okehampton and Sheppards leases were vaccinated or would be in the future.
A spokesperson for the EPA did not commit to making public when approval had been given for using antibiotics at salmon farms, or when new residue reports had been published. They said disclosure would be considered as part of a review.
Neill said the public should be “informed in real-time”.
“There are better, world-class options available, and it’s time this government started protecting our waterways and the public that use them,” she said.
• This is an edited version of an article that originally appeared in the Tasmanian Inquirer.
