The Environment Protection Authority (EPA) has released preliminary findings from antibiotic residue monitoring undertaken in response to the use of the antibiotic Florfenicol to treat Piscirickettsia salmonis (P. salmonis) at salmon farm leases in southern Tasmania.
EPA Director, Catherine Murdoch, said Antibiotic Residue Monitoring Schedules were developed and issued to Environmental Licence holders following notifications of intended Florfenicol use.
“The schedules were informed by a review of scientific literature and with support from Tasmania's Public Health Services and were specifically designed to reflect the intended use of Florfenicol on individual leases, its shorter half-life, and its potential fate in the marine environment," Ms Murdoch said.
The monitoring schedules require baseline sampling prior to treatment, as well as sampling during and after treatment, to collect data on the presence and breakdown of antibiotic residues in sediments, water, and wild fish.
“This approach ensures the EPA can assess potential environmental impacts associated with the use of Florfenicol," Ms Murdoch said.
Monitoring programs were issued for the first three Florfenicol treatment events at three leases: Meads Creek, Stringers Cove, and Zuidpool, in the D'Entrecasteaux Channel and Huon River Marine Farming Development Plan Area.
The EPA's preliminary report provides an initial assessment of results reported from samples collected at baseline, mid-treatment, and at one- and seven-days post-treatment, summarising laboratory analysis of 286 sediment samples, 104 water samples, and 119 pooled wild fish samples.
The report outlines that Florfenicol has not been measured in sediments within or external to treatment sites during the first three treatment events. Florfenicol was measured in water samples in low concentrations mid treatment but was not present in water samples at a distance greater than 35 metres from the lease boundaries seven days after treatments were completed. Florfenicol has been measured in two of the 119 pooled fish samples collected.
The preliminary report indicates that the presence of Florfenicol in the marine environment would be expected to be limited to low concentrations during treatment and up to seven days after treatment. The report outlines that initial results indicate that concentrations of residual antibiotic present in the environment after the first three treatment events are unlikely to present a risk to the Tasmanian Marine environment.
Ms Murdoch said the findings do not represent a full environmental risk assessment of Florfenicol use in the Tasmanian marine environment.
“A comprehensive risk assessment requires analysis of all environmental samples collected under the entire Therapeutant Residue Monitoring Schedules issued to licence holders."
The EPA anticipates that a full environmental risk assessment, including the establishment of guideline values for Florfenicol use in Tasmania, will be completed in early 2026 once all laboratory results are received.
A final report for each antibiotic treatment event will be published on the EPA website when monitoring has been completed.
Preliminary results and associated documents can be viewed on the EPA website at Preliminary analysis of environmental samples for Florfenicol in southern Tasmania | EPA Tasmania
ENDS.
Published on:
22/12/2025