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September 08, 2015
On the one hand, experts from the Department of Primary Industries point out the disease, called mycobacteriosis, has been linked to a degraded environment and warn the low oxygen levels and complex marine environment in the harbour increases the risk of disease spread among salmon, ABC Rural reported.
Senior Lecturer in veterinary pathology at the University of Adelaide and staff of the Department of Primary Industries, Parks, Water and the Environment (DPIPWE), Dr Stephen Pyecroft, explains in this regard: "You get an increased number of those bacteria if you have low dissolved oxygens, high levels of detritus, and you get into what we call an eutrophic environment (high amount of nutrients from fish waste).”
Besides, a DPIPWE spokesperson explained that mycobacteria is a common environment bacterium, found in soil and water and that it was uncommon for the disease to be found in Atlantic salmon.
"At this stage the incidence of its detection in samples from Macquarie Harbour is quite low, with seven of 79 submissions to the Animal Health Labs indicating its presence. The detection of this bacteria does not represent a disease outbreak, but rather that some fish have picked up this infection," the spokesperson stressed.
DPIPWE highlighted the disease is also commonly called "fish tuberculosis" and can spread between fish through contaminated water sources, consumption of contaminated feed, and cannibalism of infected or dead fish.
Fish can harbour the disease, which is not fatal in all cases, for long periods of time and it is possible for them to recover if the environmental conditions change.
In addition, DPIPWE experts ensure infection from fish to human is extremely rare and has been associated with infected cuts on hands or people with compromised immune systems.
On the other hand, referring to the data released by DPIPWE, Greens Senator Peter Whish-Wilson claimed: "It's just another piece of a jigsaw puzzle which suggests to us that unless we diffuse it Macquarie Harbour is a ticking time bomb for the salmon industry and for potentially the wider and broader eco-system."
For his part, Professor of Marine Ecology and Director of the Centre of Environmental Sustainability at the University of Technology in Sydney, Dr David Booth, said: "It's such a stratified estuary, the bottom layers of the water have incredibly low levels of oxygen, this means it's already a situation where it's almost at tipping point."
"If the salmon farms aren't correctly managed not only could they damage themselves but it could have a flow on effect to the environment," the professor added.
The companies Tassal, Huon Aquaculture, and Petuna have been expanding fish farming in Macquarie Harbour over the last five years.
Source: FIS News