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Dirty Tricks Leave Dirty Tracks
Humans don't like noise pollution, but for marine animals it is much worse. Sound travels much farther underwater, hundreds to thousands of kilometres, and can cause physical damage and behavioural changes to wildlife. Dolphins, whales, and penguins are particularly at risk. Peer reviewed research overseas indicates that noise from salmon farming is likely causing irreversible harm to our most beloved species. And yet, astonishingly, we have very little research on these effects in Tasmania.
Noise Pollution: Sonic Torture of Animals
Flaw 2: Hazardous Wastes
For years the Tasmanian salmon farming industry has been getting away with egregiously negligent practices, leaving evidence of their pollution everywhere. Ocean pens create dead zones on the seafloor and uncontollable jellyfish blooms, while a floating rubbish dump of lost and broken equipment presents a treacherous hazard for boaters. Meanwhile, the inland hatcheries release putrid effluent raising the frightening spectre of neurodegenerative disease for those consuming drinking water downstream.
There is another very serious human health threat from salmon farming: heightened risk of boating accidents from colliding with floating debris. We might think of marine debris as being unsightly ropes or soda bottles on the beach, or perhaps the floating bag or two posing a threat to unsuspecting turtles. But it can be far more serious, life threatening even.
Most of the debris coming from fish farms is things like plastic tubing or ropes. Mind you, a rope around your prop can stop your boat so fast that you are flung forward or even cast out. But boaters pray that the big items either sink or become beached. Imagine cruising along at a good clip and slamming into a piece of debris floating just under the surface of the water. No sign of anything there until whammo, your keel is damaged, there goes your stability, and your boat flips over before you even realise what has happened.
Dead Zones Under Fish Farms
Motor Neurone Disease via Our Drinking Water?
Salmon farming blankets the seabed with sludge -- a thick rain of excrement that leads to hypoxia, or low oxygen. Species who can swim, scurry, or dart away, flee for their lives. But those who cannot, simply perish, their habitat no longer able to support life. It's a disgusting way to raise food for human consumption. But there are other far more frightening implications:
Remobilisation of Heavy Metals: legacy heavy metals like mercury and arsenic are re-activated into the food chain in low-oxygen conditions.
Stimulate Blooms of Jellyfish and Toxic Algae: As vulnerable ecosystems become more heavily impacted by industry, opportunistic species like jellyfish and toxic algae are too often the result. We already see these increasing in Tasmania.
Threats to Endangered Species like the Handfish: The Critically Endangered Handfish are being run out of their last stronghold, a couple of rocks within reach of the algae being stimulated by salmon farming. It seems inevitable that these fish will go extinct.
There is growing concern that inland salmon hatcheries may be stimulating contamination of our drinking water supplies with a type of neurotoxin that is strongly associated with Motor Neurone Disease, a debilitating and lethal neurodegenerative disease.
The Nightmare of Net Cleaning
Jellyfish have an unusual life cycle: when the jellyfish has babies, they grow up to be tiny polyps, and when the polyps have babies, they grow up to be jellyfish. These polyps -- or hydroids -- are highly invasive, fast-growing, and stingy. Salmon farmers must clean them off the nets to protect the fish from being stung. However, this creates several major problems:
Gill disease in the salmon: fragments from cleaning irritate and injur the salmon's delicate gills
Impacts on other species: other species are assaulted too by these irritants. However, nobody nurses them back to health or even tracks these impacts.
Stimulates rapid re-growth: the mechanical action of cleaning stimulates the hydroids to grow more vigorously
Seeds even more hydroid colonies: the fragments act like seeds to grow thickets of new colonies, adding to the problem
Image Pond Scum CSIRO CC BY 3.0