Farmed Salmon Issues: Some of the Environmental Issues Can Be Resolved

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In the previous post I wrote a bit about the problems associated with farmed salmon – these fish are relatively unhealthy to eat due to the toxins in their bodies. The toxins get into the farmed salmon through the pellets that they are fed and the medications the salmon are given for the control of parasites and disease, and there is not much to be done about that problem at the moment. But there are available solutions to the negative impact these salmon farms have on the environment, so although the fish may be unhealthy to eat, at least the problems generated by the farms can be reduced.

Typical Salmon Farm Pen (Creative Commons Photo)

The following review is from Orca Network’s informative summary on the problem with fish farms:

The farming of fish such as salmon so high up the food chain is an extremely efficient way of concentrating contaminants. Some fish feed is so contaminated it should be disposed of as hazardous goods rather than fed to farmed fish destined for human consumption.

Yet, fish feed companies have known about PCB contamination, for example, for over 20 years. Recent scientific research has revealed contamination in Canadian, Norwegian, Scottish and Irish farmed salmon. Dioxin contamination of fishery products is now well known with DDT, chlordane and hexachlorobenzene recently detected in 97% of ‘fresh’ (i.e. farmed) salmon on sale in the UK (the only negative sample was the one wild fresh salmon sample) (Cameron: 2002c, PRC: 2002)

…Salmon farming is running on empty – it is literally running out of fuel. Such is aquaculture’s insatiable growth that it already uses up ca. 70% of the world’s fish oil and ca. 35% of the world’s fish meal (Tacon and Forster: 2001, Tacon and Barg: 2001).

Canada’s David Suzuki Foundation provided the following information:

…there can be other additives in the feed such as colouring agents (to make the farmed salmon flesh pink), binders and antioxidant preservatives. There is also an increasing use (limited at the moment) of immunostimulats.

To reduce the number of times the nets have to be cleaned, farmers will apply antifouling paints to the nets. The most commonly used paint in B.C. is copper based, where the copper is the active ingredient. The copper can make its way into marine waters by slow leaching of the paint or when the paint is striped during net cleaning.

Another toxic metal that is emitted by salmon farms is zinc. This is because zinc sulphate is added to salmon feed as a way to help the fish avoid contracting cataracts…

48 per cent of the farms had sediment concentrations of copper and zinc which were above what the government considered “safe”.

The farms themselves have far-reaching impacts on the ecosystem which extend well beyond the areas where the farms are located. The non-native Atlantic Salmon escape in mass numbers, and cause havoc with wild salmon:

The reported escapes of farmed salmon in BC between 1987 and 2001 fluctuates from one year to the next with the average being about 90,000 escapes per year for the period 1990-2000. Since the 1980’s, salmon farms in BC have switched from farming pacific species to mainly Atlantic salmon. This is reflected in the escape figures, which are now predominantly made up of Atlantic salmon.

Finally, research published in Science
found that:

The louse-induced mortality of pink salmon is commonly over 80% and exceeds previous fishing mortality. If outbreaks continue, then local extinction is certain, and a 99% collapse in pink salmon population abundance is expected in four salmon generations. These results suggest that salmon farms can cause parasite outbreaks that erode the capacity of a coastal ecosystem to support wild salmon populations.

However, there is a viable alternative to the environmental problems caused by open pen fish farms, which although not a long term solution might buy our salmon-hungry world some time while we restore the wild salmon population.

Being tested now and with plans for future development are closed-system tanks, made of fiberglass and designed to treat wastes. Depending upon how the wastes are managed and the materials that are used that contact the environment, these tanks could virtually eliminate the contamination to wild salmon and by extension, to the orcas that feed upon them.

J40 catches a salmon off False Bay, September 8, 2008 (CWR photo by Astrid van Ginneken)

But the industry has a long way to go before they produce a healthy, natural fish fit for consumption.

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