Management of Therapeutants (including antibiotics)

​The use of vaccines and treatment of diseases at finfish farms are important fish health and welfare matters that are overseen by Biosecurity Tasmania. Public health issues associated with the ​use of antibiotics are the responsibility of the Department of Health. 

Treatment of marine farmed fish only occurs based on veterinary advice and has declined significantly since 2006 - 2009 due to the development of vaccines, as shown below. 

​​Figure 1: Use of antibiotics (active medication in kg/year) between 2003 and 2023​​

Graph of antibiotic usage - see accessible version. 

Accessible version of this graph

The EPA's responsibility is to ensure that the use of antibiotics in finfish farming does not cause environmental harm. This is done through monitoring of antibiotic residues in the environment. 

Following notification of medication events, the EPA requires licence holders to conduct comprehensive monitoring of antibiotic residues in seabed sediments and in wild fish. 

The monitoring schedule developed by the EPA is designed to track potential antibiotic residues over time and assists in the understanding of antibiotic fate in the receiving environment.  Monitoring intensity (e.g. number of monitoring sites) is determined using a risk-based matrix taking into account the amount of medicated feed used during treatment and site-specific factors. 

For wild fish sampling, the end of the monitoring program coincides with the number of 'degree days' corresponding to the withholding period for farmed salmon specified under food safety regulations.   

Sediment monitoring is required to continue until levels determined through analysis at an approved laboratory are below the specified threshold. 

It is the EPA's current practice to make antibiotics monitoring reports public after residue monitoring is completed, usually within a timeframe of 6 months from the commencement of monitoring. Interim reports may be issued in the case of more prolonged monitoring events.​

The EPA's approach is consistent with findings of a risk assessm​ent undertaken by Food Standards Australia and New Zealand (FSANZ), which was undertaken to identify the risk associated with consumption of recreationally caught wild fish and escaped farmed fish following treatment with oxytetracycline (a commonly used antibiotic). The FSANZ risk assessment did not consider the commercial harvest of salmon, as salmon destined for sale must comply with the Australian New Zealand Food Standard Code which specifies a maximum residue limit of 0.2 mg/kg. 

To date, antibiotics residue levels observed in wild fish samples collected under EPA monitoring requirements have remained well below the maximum concentration of antibiotics in wild fish flesh which was assumed for the FSANZ study. 

Details regarding specific antibiotics residue monitoring events can be accessed on​​​​​​​​​ the web page for each marine farming region (see region links on this page).