Salmon farming and heavy metal pollution: the facts

We are often (once again, wrongly) on the receiving end of claims that salmon is full of chemical and environmental contaminants. If that were so, why would we submit our salmon and trout for routine testing by the Federal Government AND publish the results?

Since we began reporting to the National Residue Survey in 2000 there has been no detection of any additives, anthelmintics, contaminants, hormones or insecticides in Huon Aquaculture products (INCLUDING zero Ethoxyquin) – click on survey results below to see copies of the results from the Federal Government.

The most current results (2022) show that lead was not detected in Huon fish at all and mercury was detected at a level of half the MRL – ie 50% less than what the authorities recommend is an acceptable level in Australia. The source of heavy metals in both farmed and wild fish comes from what they eat; the difference is that we know exactly what our fish eat whereas both the location and type of food eaten by individual wild fish is unknown.

Click here for Huon Salmon survey results

For more information on the National Residue Survey (industry-wide results), visit: https://www.agriculture.gov.au/ag-farm-food/food/nrs

Salmon farming is not a source of heavy metal pollution.

In Macquarie Harbour, the source of heavy metals is river outflows from adjacent catchments containing high levels of heavy metals accumulated from historical mining activity. In the Derwent River, the main sources of heavy metals are the zinc smelter at Lutana and urban stormwater run-off (as identified by the Derwent Estuary Program).

Heavy metals are not a health risk in Tasmanian farmed salmon. Huon has sampled our fish for heavy metals, primarily targeting gill, liver and kidney which are scientifically recognised as the organs most likely to show up any elevated levels of heavy metals in fish. All results, including in Macquarie Harbour, have been well below the levels reported by the Food Standards Code of Australian and New Zealand (FSANZ) as safe.

There is no scientific evidence to indicate that aquaculture derived nutrients are likely to enter the Derwent Estuary system at high enough loads and for long enough to then cause the required sustained hypoxia to cause heavy metal release. Those interested in the facts around this topic should contact the internationally recognised experts at the Institute of Marine and Antarctic studies (IMAS).

Nonetheless there is an extensive monitoring program in the Derwent Estuary and Storm Bay, including scientists from CSIRO and IMAS to monitor factors like oxygen concentration in the water and heavy metal levels in fish and shellfish.

The Tasmanian Department of Health website provides public health alerts in regard to consumption of shellfish and certain fish species (e.g. flathead) which is based on a long-term monitoring program.

Some detractors have claimed that eating farmed salmon from Macquarie Harbour and Storm Bay may lead to a human health event similar to that which occurred in Japan at Minamata in 1956 (sometimes referred to as Minamata disease).  Minamata disease in the local Japanese human population was caused by the toxic effect of methylmercury which had accumulated to high levels in the local fish and shellfish. The source of the methylmercury was wastewater released from a chemical factory, with methylmercury reported to be around 5% of the wastewater. This bears no relevance to farmed salmon in Tasmanian conditions.

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