Like any farming endeavour where a large number of animals are kept together in close quarters, salmon farming is rife with disease. This unnatural environment is a breeding ground for pathogens, requiring brutal measures of treatment and control. The Atlantic salmon species that has been introduced is susceptible to diseases of native fish populations, and meanwhile, native fish populations are exposed to a host of devastating new illnesses.
The salmon industry must engineer and manipulate its fish to an alarming degree, just to ensure their survival long enough to be harvested. This raises serious points for our consideration. Firstly, do we want to be eating meat that is steeped in antibiotics and pesticides (not to mention distress)? Secondly, can we endorse our food coming from an industry beleagured with animal welfare complaints? History has proven that there are serious consequences when we meddle in previously intact and self-regulating balanced ecosystem.
Amoebic Gill Disease (AGD)
The biggest threat to the salmon industry is gill disease. Indeed, it can kill up to 2% of fish per day if not treated. Tassal, Tasmania’s largest salmon company, has admitted that it is standard to lose 17 percent of stock prior to harvest — rather alarming compared to the 3 to 5 percent mortality rate in intensive chicken farming! The industry spends a whopping 20% of its production costs on managing just this one problem. The scale of these losses and costs would be incomprehensible in just about any other industry.
One of the worst diseases that can infect farmed salmon is what is known as Pilchard Orthomyxovirus (POMV). It is a type of Herpes virus. Don't worry, there is no indication that you may catch herpes from eating salmon that have it. (Whether you want your salmon to have herpes is another issue.)POMV is one nasty virus. In late May 2018, a report came to light that more than 1.35 million farmed salmon had died in the previous six months due to POMV.
Salmon lice are a biblical plague on farmed fish. Salmon lice are marine crustaceans, smaller than a fingernail. They have a shield-shaped body and the females bear two long egg strands. Their mouth closely resembles a hypodermic needle, which they use for puncturing the skin and sucking blood and juices. They literally bite onto the fish and eat the fish alive. In severe infestations, they can strip much of the skin and flesh off a fish's face, fins, and genital area, such as in the photos here, here, and here.
Intensification Breeds Infection
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Image Oleg Gamulinskiy at Pixabay CC BY 3.0