Fish, salmon farms and empty oceans

Anyone who cares about wild salmon and tries to reconcile the tolerant attitude of the Department of Fisheries and Oceans (DFO) to the environmentally damaging practices of salmon farming must confront a bewildering question. If DFO is responsible for the well-being of Canada’s wild salmon stocks, why does it endorse salmon farming in principle and allow open net-pens in practice when such an industrial practice is a clear risk to wild stocks and causes demonstrable harm to the very species and habitat that DFO is legally mandated to protect?

Concurrently, the emission of carbon dioxide from burning fossil fuels is acidifying the world’s oceans. About a third of the CO2 we emit from industrial activity is added to the atmosphere to cause global warming, a third is absorbed by plants and a third is dissolved into oceans. When carbon dioxide mixes with salt water, it forms carbonic acid, and this process is lowering the ocean’s pH — making it more acidic.



How serious is this acidification process? Studies at the Svalbard Archipelago in the Arctic Ocean have found that north pole seawater will likely reach “corrosive” levels of acidity within 10 years. Professor Jean-Pierre Gattuso of France’s Centre National de la Recherche Scientifique, told an international oceanographic conference, “We knew that the seas were getting more acidic and this would disrupt the ability of shellfish — like mussels — to grow their shells. But now we realize the situation is much worse. The water will become so acidic it will actually dissolve the shells of living shellfish” (Globe & Mail, Oct. 7/09). The other oceans of the world are also becoming more acidic, and they will follow the fate of the Arctic Ocean. When this happens, the foundation of the marine food chain will collapse and sea life as we know it, including wild salmon, will cease to exist.

As well as acidifying, oceans are also warming — indeed, oceans are the principal heat sink that has been absorbing most of the planet’s warming. Warmer water contains less dissolved oxygen. Salmon, like other fish, breathe this vital gas. The research of Gary Shaffer at the University of Denmark calculates that in a worst case-scenario, the 400-plus “dead zones” in the world’s oceans could increase 20-fold if we don’t control greenhouse gas emissions (New Scientist, Jan. 31/09). Less oxygen means less vital salmon and lower survival rates at sea.

Ray Grigg, canada.com, 13 November 2009. Full article.

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