Salmon Farming November 2014

Salmon farming production has increased by around 171% over the past decade in Tasmania and salmon companies have stated that they want to double production by 2030. Whilst the industry provides much-needed regional jobs, anecdotal and scientific reports suggest that impacts are increasing, monitoring is inadequate and the expansion of the industry needs to slow down and be done in a more strategically planned and transparent way.

There are several current and proposed expansions to salmon farming areas in the D’Entrecasteaux Channel and Huon regions in south-east Tasmania.  However these are assessed and approved by government on an ad-hoc basis that creates numerous processes, making it difficult for the local community, conservationists and other stakeholders to engage properly and ensure their concerns are adequately and strategically considered. For many people, it feels as if the industry and its impacts are on an endless growth curve.

An independent report commissioned by Environment Tasmania – ‘Review of Monitoring the Environmental Effects of Salmon Farming in Tasmania’ by Hugh Kirkman – found that the monitoring of salmon farming impacts was inadequate; what monitoring is being done is not released in a timely manner; and a regional plan is needed, to include all uses and conservation of waterways, particularly as the effects of climate change become greater and there is a need to increase natural areas’ resilience.

Research suggests there has been environmental degradation, including the creation of dead zones (localised oxygen depletion), nutrient enrichment in bottom waters of the Huon Estuary, a long-term increase in phytoplankton, and toxic algal blooms. There is minimal data available and no ongoing monitoring for the effect of nutrients or salmon-cage detritus on reefs or seagrass in south-east Tasmania, despite recent studies showing impacts of nutrients on macroalgal (kelp) communities occurring hundreds of metres away, wherer, impacts are legally limited to just 35m from lease areas. Commercial abalone divers and local residents in the D’Entrecasteaux Channel and Huon River region are also reporting ongoing algal growth, dusty sediment settling on reefs, and fewer fish.

The report also found that additional research is urgently needed, to assess impact and recovery of seafloor ecosystems over time. The current annual frequency of video samples is inadequate for a meaningful assessment of impacts on sediment under cages, as it does not alert managers to impacts that may do permanent damage to the seafloor and fauna. As opposed to annual surveys, video images and transects should be made at least monthly and triggers for responsive action should be set.

Whilst improvements have been made, seals, birds, and dolphins all run the risk of being caught in aquaculture nets and dying. At least 144 ‘protected’ seals have died as a result of fish farming since 2009. Forty-nine of these deaths were the direct result of Tassal and Huon Aquaculture’s operations in 2012 and 2013.

Sometimes referred to as the battery hens of the sea, up to 50,000 salmon can be put in one circular cage. It takes 1.7kg of wild fish in addition to other inputs, such as grain and chicken, to produce 1kg of farmed salmon, with approximately 5% of this feed entering the marine environment as nitrogen. Fish farms are the most significant source of ammonium – a form of nitrogen – in many marine areas, due to the bacterial mineralisation of faeces and feed. This can lead to localised oxygen depletion and excess nitrogen changing nutrient dynamics and the frequency of algal blooms.

We can minimise the impacts and control the expansion of salmon aquaculture to ensure a healthy future for Tasmania’s unique natural environment and all that relies on it. However, the salmon-farming industry expansion plans in south-east Tasmania will continue to drive social division and provoke opposition whilst these environmental impacts persist, and coordinated regional planning and transparency fail to occur. To read the report and find out how you can help, go to