The National Oceanic and Atmospheric Administration’s Fisheries division explains that aquaculture involves the breeding, rearing and harvesting of fish and shellfish in ponds, rivers, lakes and the ocean. While some of these fish are produced for commercial use, many are released into the wild to rebuild “wild populations or coastal habitats.” The proliferation of these fish on the open market directly affects the nutritional value of the seafood we buy, and of course, their release into the wild will have long-term effects on the environment.
With that in mind, a new study by researchers from the University of Melbourne is cause for real concern. The study, published in the Journal of Experimental Biology, found that at least half of all the world’s farmed salmon are deaf as a direct result of the accelerated growth rates found in aquaculture.
The research team determined that these quicker growth rates cause deformity of the otoliths – the tiny crystals in the fishes’ ears which detect sound – causing devastating hearing loss.
Tormey Reimer, the study’s lead author from the School of Biosciences at the University of Melbourne, explained, “We looked at over 1000 otoliths from fish farmed in Norway, Chile, Scotland, Canada and Australia, and found that this deformity was extremely common, but only in farmed fish. Then we found that we could reduce the incidence of the deformity by reducing how fast a fish grew. The fastest-growing fish were three times more likely to be afflicted than the slowest, even at the same age. Such a clear result was unprecedented.” (If environmental issues are of concern to you, stay in the loop by bookmarking Environ.news)
While there were other contributing factors, including diet, exposure to sunlight and genetics, the overwhelming cause of this type of deformity was found to be the expedited growth of farmed fish.
The fact that scientists have detected this one deformity in farmed fish raises the question of what other undetected, and possibly unhealthy, changes might be taking place in these fish as a result of the conditions in which they are farmed.
What is clearly understood by scientists is the fact that a fish is not just a fish when it comes to the differences between wild and farmed fish.
Tilapia are particularly problematic in this regard. Since this species is especially hardy and adaptable, tilapia farmers can get away with using very low-quality feed, diminishing the eventual nutritional value of such fish.
A study conducted back in 2008 by researchers from the Wake Forest University School of Medicine, found that farmed tilapia contain very low levels of the essential fatty acid omega-3. Worse, the report concluded that the “inflammatory potential of hamburger (80% lean) and pork bacon is lower than the average serving of farmed tilapia (100 g).” Farmed tilapia were also found to contain high levels of arachidonic acid, an omega-6 fatty acid which may cause inflammation, and has been linked to brain disorders like Alzheimer's.
Studies like these are not a reason to despair and stop eating fish, however; their health benefits are enormous if you make the right choices. Just be sure to opt for wild-caught salmon, tilapia and other fish next time you put seafood on the dinner menu.
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