How will global warming affect our salmon farming industry?
- Salmon farming requires water temperatures of 8 – 14 degrees Celsius. Recently water temperatures in Hobart ranged from 11 to 15 degrees, and there have been large fish losses during heat spikes, most recently in the Tamar River. Global warming means that our ocean temperatures are rising quite rapidly, and will continue to rise, which will make current salmon farming marginal at best within a few years.
- Worldwide, the salmon industry is exploring moving to colder deep ocean areas. But there is a much greater effort towards raising salmon ashore in huge tanks, using water that is filtered and recycled with fish waste removed and used for agricultural fertiliser. Tasmania is falling rapidly behind.
How does salmon farming work?
Salmon production takes about 3 years. Hatching occurs in controlled freshwater environments, usually on land, and when the salmon are about a year old, they are transported to seawater pens. They reach a harvestable size after 12-18 months, then they are killed and prepared for sale.
Surely fish farming on land would be too expensive, just as contaminating, or just too impractical?
- Any potential contamination from closed-loop fish farming can be strictly monitored. The main effluent from a fish farm is faeces – and that’s a good agricultural fertiliser which is easily marketed.
- The set-up costs of closed-loop fish farming ashore are considerable. However, the costs of running the installations is far less than the cost of maintaining fish pens that require towing, cleaning, repairing and protecting from weather.
- Is salmon farming on land viable? The industry says no, but does not provide any evidence for their exaggerated cost and energy claims. Here is a simple analysis of the current situation, showing how land-based aquaculture is increasing around the world (4 pages, PDF).
Surely fish farming out at sea would be too expensive, and incredibly difficult and dangerous?
- Scandinavian producers have developed ways of farming fish in deep, stormy ocean waters. There are no shortage of industry leaders overseas for Tasmanian fish farmers to follow.
- NOFF is neutral on the economics of such methods when it comes to the smaller Tasmanian enterprises, but we suspect that moving onshore would be more economically viable.
Does the technology exist to move on-shore or off-shore?
Yes. The past decade has seen huge investment overseas in developing shore-based fish farming. There is an increasing risk that overseas operators will establish land-based facilities on the Australian mainland, close to their main markets, and Tasmania will not be able to compete.
What’s happening in Storm Bay and the Tasman Peninsula
All three fish farming companies are planning massive expansions into Storm Bay. There are plans to produce 80,000 tonnes of Atlantic Salmon, which would produce five times more sewage annually than the whole of the Tasmanian population. Already there are new pens off the west coast of the Tasman Peninsula and off Bruny Island. Close to the World Heritage site of Port Arthur, Stingaree Bay is being polluted by stinking algae that covers the rocks and beaches – in the wake of Tassal re-opening its leases there and stocking its pens.