Farmed Fish Can Now Go Vegetarian… So We Don’t Have to?
I’m not sure about North America, but here Down Under “fish & chips” is a pretty big staple in the diet. In fact seafood is generally the food of choice when celebrating a sunny Christmas and Easter. Unfortunately, as many Care2 readers are well aware, the global seas are facing an over-fishing crisis. Bluefin tuna are on the absolute brink, and 70% of fisheries are fished at or over capacity.
As the world’s population booms and food demands go up, aquaculture (fish grown in tanks or ponds) has become a necessary link in the food system chain and currently provides nearly half of the world’s fish supplies. Like it or not, the demand for seafood is not going away anytime soon.
Feeding Limited Supplies of Fish with… Fish
One of the main issues with farmed fish, however, is that many species are fed a combination of fish meal and fish oil which is produced from wild fish. As a result, we end up using limited wild fish stocks to feed farmed fish.
The research team from the Institute for Marine and Environmental Technology have developed a completely plant-based diet that works for marine fish raised in aquaculture. Their findings were published in the journal Lipids, supported by another paper published in the Journal of Fisheries and Aquaculture.
Author of the study, Dr. Aaron Watson, told the University of Maryland’s Center for Environmental Science, “Aquaculture cannot sustainably grow and expand to meet growing global population and protein demand without developing and evaluating alternative ingredients to reduce fish meal and fish oil use.” Current practices see carnivorous fish such as sea bream and striped bass fed with five pounds of wild-caught fish in order to produce one pound of “gourmet” fish. The practice is expensive, unsustainable and actually quite ironic given the purpose of aquaculture.
The Vegetarian Diet for Fish
Fish oil has become quite limited and expensive thanks to the demand for it as a health supplement. The researchers managed to replace fish oil with soybean or canola oil, supplemental fats from algae and protein supplements such as taurine (carnivorous fish and their prey tend to have high levels of taurine).
A mixture of wheat, corn and soy was used to replace fish meal.
Co-author Dr. Allen Place said, “This makes aquaculture completely sustainable. The pressure on natural fisheries in terms of food fish can be relieved.”
“We can now sustain a good protein source without harvesting fish to feed fish.”
Whether the nutritional value of the fish raised on this meal plan will be affected remains to be seen, but I have a sneaky suspicion it might, given the nutritional changes in grain-fed vs. grass-fed cattle for example.
Lowering the Mercury
One noted benefit of raising fish on a plant-based diet is that mercury levels were found to be as much as 100-fold lower. With mercury toxicity being incredibly harmful to the body, aquaculture may soon be favored over wild-caught fish, easing pressure on wild populations.
“Right now, you are only supposed to eat striped bass once every two weeks,” said Place. “You can eat aquaculture-raised fish twice a week because levels are so low.”
Fish raised on a vegetarian diet could revolutionize the fishing industry, with potentially huge implications for wild fish populations, aquaculture as an enterprise and the health of consumers.
Of course we could always just stop eating fish.
Photo Credit: Thinkstock