We believe that disease control in salmon requires a holistic approach. Good site management, fish husbandry and rigorous biosecurity measures are central to reducing the risk of disease outbreaks and controlling the spread of infectious diseases.
Vaccines are important in preventing disease outbreaks but cannot control all losses. Medication such as antibiotics are also important but should only be used as a last line of defence to avoid significant animal welfare issues and stock losses. This mind-set means that we are continually working to develop proactive diet regimes and vaccines to allow our salmon to combat known illnesses and lead healthy lives.
- Antibiotic use on Huon farms is rare.
- Like all farming operations, sometimes our fish can get sick and it is important that we have the ability to responsibly treat with antibiotics on those rare occasions, to ensure fish health and welfare needs are met.
- From 2017 to December 2021 no antibiotics were used across any marine leases (both in Macquarie Harbour and in South East Tasmania). In January 2022, some smolt pens at our Yellow Bluff lease were treated. Huon will report actual grams/T produced (in accordance with the Global Salmon Initiative GSI annual reporting requirements) at completion of end of our reporting year (ie, CY 2022).
- The correct use of antibiotic is critical in reducing antimicrobial resistance which is why our veterinarians follow the World Health Organisation (WHO) guidelines for the use of antibiotics in livestock industries. WHO does not preclude the use of antibiotics in livestock industries, including salmon farming.
- Our vets only prescribe antibiotics as a last resort and always following a full investigation, confirmation of diagnosis through laboratory testing of fish health samples and after confirming antibiotic sensitivity of causative organisms.
- Huon voluntarily and publicly reports all antibiotic use (Huon owned and operated marine and freshwater sites) as well as reporting their use to the State Government in real time.
- Our use of antibiotics across our freshwater operations (ie hatcheries) is restricted to our non-consumptive flow-through hatcheries (which only hold on average around 20 per cent of our total smolt biomass) – notwithstanding that condition, the last use in one of our flow-through hatcheries was in January 2019—see below for details.
- Antibiotics are prescribed by a qualified veterinarian and there is a strict withholding period which means that any traces have completely passed through the fish long before it is harvested.
- Huon also participates in the annual independent National Residue Survey to monitor levels of therapeutants, demonstrating that we comply with a maximum residue limit. Huon has never had any antibiotic residues detected in our products.
A last resort
We believe that antibiotics should only be used as a last resort which is why we practice a holistic approach to farming. Integral to our approach is good site management, low stocking densities, the development and use of vaccines, feeding a high-quality diet, and keeping our fish as calm and low stress as possible.
In January 2019, we used antibiotics to treat small fish at two of our freshwater hatcheries. The fish in these hatcheries were prescribed the treatment as they had Yersinia (a coccobacilli bacterium which is naturally present in some water).
We will never use antibiotics at our closed-loop hatcheries as those systems rely on good bacteria within the waste treatment system to treat the water and as anyone who has taken antibiotics will know, their use kills both the good and the bad bacteria.
Huon does not use any of the antibiotics listed as Critically Important by the WHO – despite WHO guidelines stating that this would be acceptable under certain defined circumstances.
(WHO categorises all antimicrobials used in human medicine as either Critically Important, Highly Important or Important in the medically treatment of bacterial infections in humans; in effect placing a value/importance on each antimicrobial in terms of its effectiveness in combating bacterial infections).
Huon only uses Trimethoprim (Dihydrofolate Inhibitor) and Oxytetracycline (Tetracycline) which are on the WHO Highly Important list. All use is in early life stages, well over 12 months prior to harvest, significantly exceeding required withdrawal periods so there are no residue issues in final products.
The Tasmanian industry as a whole independently made the decision many years ago not to use antibiotics such as Oxolinic Acid (Quinolone) and Amoxycillin (Penicillin) which are compounds listed by the WHO within Critically Important classes of antimicrobials. This decision was made despite these particular antibiotics being used in salmon farming across other countries.
Preventing antibiotic resistance
To prevent and control the spread of antibiotic resistance, the agriculture sector (including aquaculture) can:
- Only give antibiotics to animals under veterinary supervision;
- Not use antibiotics for growth promotion or to prevent diseases in healthy animals;
- Vaccinate animals to reduce the need for antibiotics and use alternatives to antibiotics when available;
- Promote and apply good practices at all steps of production and processing of foods from animal and plant sources; and
- Improve biosecurity on farms and prevent infections through improved hygiene and animal welfare.
Voluntary public reporting
We publicly and voluntarily report antibiotic use across Huon owned sites, at conclusion of reporting period. Huon adheres to the Global Salmon Initiative (GSI) annual reporting requirement (of active pharmaceutical ingredients (API) used (in grams) per tonne of fish produced (LWE) in the period (Huon adopts CY reporting following acquisition by JBS).
Withholding period and residue testing
In the event that antibiotics are used in a population of fish at sea, we adhere to strict withholding periods which allows any therapeutants to pass through the fish before it is harvested for consumption.
Every year Huon participates in the independent annual National Residue Survey to monitor levels of a wide variety of compounds and therapeutants, across the salmon industry, ensuring we comply with a maximum residue limit, which refers to the highest concentrations of a chemical residue that is legally permitted or accepted in a food, based on good agricultural and chemical use practices. The industry-wide combined results can be found on the National Residues Survey website. Notwithstanding the industry-wide NRS results, Huon voluntarily publishes our flesh testing results here.
On occasion we also conduct voluntarily flesh testing which is not required by government regulations. When we do this, we publish the results on our website