Antibiotic name and dosing period
Florfenicol 100% Active. Nine 10-day treatments under 8 Medication Authorities, with the first treatment starting on 12 November 2025 and the final treatment finishing on 19 January 2026.
Summary of sampling rounds undertaken
The original monitoring schedule required that water, seabed sediment and wild fish samples were collected before, during and after treatment (baseline, mid-treatment, day 1 post-treatment, day 7 post-treatment, day 14 post-treatment, day 21 post-treatment).
An Addendum to the Monitoring Schedule was issued due to the receipt of additional Medication Authorities for this lease. The Addendum required that these samples be collected weekly until all treatments on the lease had finished and 2 consecutive results below the limit of reporting were received and the Director had authorised that sampling be stopped.
Samples were collected at sites both inside the lease (pen bays and centroids) and outside the lease, including compliance sites, transect sites, control sites (i.e. at an untreated lease) and reference sites.
In total, 83 pooled samples of wild fish, consisting of 3 individual fish per pooled sample, and 372 individual wild fish samples were caught across 3 zones (within 1 km, between 1-3 km and greater than 3 km) from the lease boundaries. The 455 wild fish samples included 23 benthic and pelagic species, with Australian salmon, flathead and wrasse the most commonly captured.
In total, 327 sediment samples and 420 water samples were collected at multiple distances from the pen bays and including reference sites up to approximately 9.1 km from the lease boundary. The Addendum also specified that the required water samples be collected from 2 additional depths at each site.
Assessment of compliance against the schedule issued by the EPA
The report is compliant with most of the requirements of the Therapeutant Residue Monitoring Schedule - Marine Farming Lease No. 141 (South of Zuidpool Rock), the ADDENDUM - Therapeutant Residue Monitoring Schedule - Marine Farming Lease No. 141 (South of Zuidpool Rock) and section 28(2) of the Environmental Standards for Tasmanian Marine Finfish Farming 2023.
Non-compliance with the water sampling requirements has been identified, with some post-treatment samples not being collected at pen bays as specified in the monitoring schedule. Water sampling at lease centroids, external and reference sites was undertaken as required. The EPA is currently considering its response to this matter.
Summary of findings in report
The results outlined in this report align with the EPA's Preliminary analysis of environmental samples for florfenicol in southern Tasmania with negligible detections of florfenicol in seabed sediments and rapid depletion of the low level detections in the water column in the days after treatment.
EPA's assessment of potential environmental impacts
The EPA is currently reviewing the accumulated monitoring data in relation to the use of florfenicol at Tasmanian salmon farms. The EPA is currently finalising its work to establish a guideline value for ecotoxicity of florfenicol in aquatic environments. Results will be released in due course.
Statement from the Director of Public Health
Public Health Services notes the reports of florfenicol residue detected in 8 of 143 individual or pooled wild finfish samples (1 sardine and 7 sand flathead) caught within 1 km of a treated lease. Eating typical amounts of these wild finfish does not pose a risk to health.
Florfenicol residue above the level of reporting was not detected in any of 112 individual or pooled wild finfish samples caught between 1 km and 3 km of a treated lease, or in any of 200 individual or pooled wild finfish samples caught more than 3 km from a treated lease.
Public Health Services has reviewed all results to date and maintains its precautionary advice, which is available on the Department of Health website.
Link to final report:
Final Report - Therapeutant Residue Monitoring Program - MFL 141 South of Zuidpool Rock (PDF 5Mb)