Half of All Farmed Fish Have Deformed Ear Bones That Cause Hearing Loss

Farmed fish have become an increasingly larger share of the world’s seafood market in recent decades—now accounting for 50 percent of global seafood consumption.
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At the same time, however, debate about the ethics, safety and health of farmed fish versus their wild counterparts has also intensified. A new study published in the journal Nature Scientific Reports finds that half of all farmed Atlantic salmon have deformed ear bones that lead to hearing loss. These salmon are 10 times more likely to have the deformity than wild fish. The findings “raise questions about the welfare of farmed animals,” said Tim Dempster, a biologist at the University of Melbourne involved in the study. It may also explain why efforts to boost wild populations by releasing farmed juveniles have proven unsuccessful. Hearing loss would prevent farmed fish from detecting predators, or restrict their ability to navigate to breeding sites, the scientists said.