A large and unprecedented salmon mortality event has unfolded since mid-February 2025 in the lower D'Entrecasteaux Channel. Huon Aquaculture Company (Huon) and Tassal operate salmon farms in this area.
Mortalities affect salmon farming worldwide and are typically elevated during summer months, including in Tasmania, when warmer waters and other factors affecting salmon health are more likely to occur. Tasmania's Chief Veterinary Officer (CVO) has made a statement on the cause of the mortality event, available at Salmon mortalities | Department of Natural Resources and Environment Tasmania.
Media Statements
Latest Media Statement
Previous Media Statements
Mortality Waste Data
New salmon mortality reporting conditions derived from the Government's Environmental Standards for Tasmanian Marine Finfish Farming are being implemented by the EPA. These conditions require the combined weight of deceased fish from finfish farms to be reported within 10 business days of the end of each month. A breakdown of tonnages reported, together with the different types of waste receiving facilities, is shown in the table below. The EPA intends to publish mortality weight information quarterly, approximately three weeks after the end of each quarter.
* This data is released pursuant to Section 23AA of the Environmental Management and Pollution Control Act (EMPCA) 1994.
Independent environmental monitoring by the EPA
In response to analytical results indicating that a small number of oil globules found on beaches in the southern D'Entrecasteaux Channel contained antibiotic residues in the parts per million range, the EPA commenced an independent environmental monitoring program on 20 March 2025. The EPA's monitoring did not detect any further antibiotic residues in water, beach sand, or fish. A report outlining the EPA's sampling methods and results is available below.
EPA Independent Environmental Monitoring Report April 2025 (PDF 289Kb)
Expanded Antibiotic Residue Monitoring Schedule
The EPA requires companies to conduct detailed antibiotic residue monitoring of sediments and wild fish following application of antibiotics to fish farm pens. Further to the usual requirements, on 7 March the EPA issued expanded antibiotic residue monitoring requirements that include sampling of water, sediments and oil globules (where present) at four beaches around the southern D’Entrecasteaux Channel that are known to have been impacted by oil globules.
Antibiotic Residue Monitoring Schedule MF141 and Signed Letter 7 March 2025 (PDF 514Kb)
Interim Antibiotic Residue Monitoring Report – April 2025
Sampling of wild fish, sediment and water was required to be conducted by Huon Aquaculture Company on five occasions between February and April 2025. An interim monitoring report containing the results for all samples collected during round 1, which occurred on the two days immediately following the end of treatment, can be viewed here:
Interim Antibiotics Residue Monitoring Report - Zuidpool (MF141) - April 2025 (PDF 2Mb)
Oxytetracycline was detected in sediment immediately adjacent to the treated pen bays and at two of the twenty-seven transect sites at significantly lower levels. No oxytetracycline was detected in sediment samples at the six ambient sites located 2 km, or further, from the lease boundaries.
Wild fish were collected from six sites, two in-lease and four ambient sites, pooled, and analysed for the presence of oxytetracycline. Oxytetracycline was detected in three pooled samples on Zuidpool North and one pooled sample at the ambient site located near Ventenat Point.
The Director of Public Health has reviewed the report and provided the following statement “Residual oxytetracycline (OTC) antibiotic was detected in several wild fish samples collected and tested on behalf of HAC under EPA monitoring requirements. These samples were collected in late February 2025, in the days after the period of OTC dosing ended, when antibiotic residue was most likely to be present in fish and the environment. These findings were consistent with the estimates used in the FSANZ risk assessment – Oxytetracycline in Tasmanian Salmon and Wild Fish that concluded that consuming foreseeable quantities of such wild fish does not raise public health concerns.”
The Director of Public Health also noted that testing by the EPA of wild fish caught in the southern D’Entrecasteaux Channel in late March 2025 did not detect antibiotic residues (see EPA report above).
The licence holder has complied with all requirements of the monitoring schedule. Additional sampling occasions may be required. This will be determined upon receipt of the results for rounds 4 and 5.
A final report containing the results for all rounds of sampling will be made available upon completion of the monitoring program.
Direction to Cease Discharge of Controlled Waste 6 March 2025
The EPA issued directions to Tassal and Huon Aquaculture on 6 March requiring removal of deceased fish and waste derived from them at a rate and in a manner sufficient to prevent discharge of a controlled waste to the environment.
Summary of Sampling and Testing Results
Due to the highly complex nature of lipid (fatty acid) profile testing and the similarity of results received to date, the EPA will no longer request such tests to be undertaken on oil globule samples. This material can be readily identified in the field and its nature is known to be consistent with fish oil.
^Collected by members of the public.
‡Collected by Huon Aquaculture Company.
Unless indicated all other samples collected by the EPA.
#DMB is dry matter basis.