Half of all farmed salmon on your plate is deaf

The quick rearing methods in aquaculture may cause large-scale variations in the inner ear of the salmon, it is apparent from Australian research.

Salmon © Getty Images/iStockphoto

Last year, allowed researchers from the University of Melbourne found that half of the kweekzalmen abnormalities of the inner ear exhibits. Now they have found the cause: the rapid growth of the animals. They publish their findings in the Journal of Experimental Biology.


The inner ear of the salmon, it features tiny crystals and sound to detect, and a small change can be all to serious hearing problems lead. In the sixties, were the first abnormalities are defined, and from the Australian research shows that 95 percent of all farmed salmon sign of the deviation. At the half of the fish leads to severe hearing loss.


The scientists found that the disease is far less frequent if the fish growing at a slower pace.

“We studied more than a thousand crystals of fish from Norway, Chile, Scotland, Canada and Australia,” says Tormey Reimer, professor of life Sciences and lead author of the study. “We determined that the deviation is very common, but only in farmed fish.”

The scientists found that the disease is far less frequent if the fish growing at a slower pace. The fastest growing fish have three times more chance of the deviation than the slowest cultured.

Five freedoms

“These results lead to serious questions about the welfare of the farmed fish,” says co-author Tim Dempster. “In many countries, the growers take into account the ‘five freedoms of animals: freedom from hunger or thirst, freedom from discomfort, pain, injury and disease, the freedom to have a normal behaviour and the freedom from fear or stress.”

Animals breeding with deviations goes against two of those freedoms, says Dempster: freedom from disease and the freedom to have a normal behavior to show. “But fish farms are very noisy places for salmon, so the hearing loss can also reduce stress. We still don’t know whether the disorder has an impact on the production.”


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