For the first time scientists have been able to develop a completely vegetarian diet that works for marine fish raised in aquaculture, the key to making aquaculture a sustainable industry.
The study was led by Aaron Watson and Allen Place at the University of Maryland Center for Environmental Science’s Institute for Marine and Environmental Technology.
Aquaculture isn’t sustainable because it takes more fish to feed fish than are being produced, said Dr Watson. But a new vegetarian diet might change everything.
In the study the team has proven that a completely plant-based food combination can support fast-growing marine carnivores like cobia and gilthead sea bream in reaching maturity just as well as – and sometimes better than – conventional diets of fishmeal and fish oil made from wild-caught fish.
Nearly half of the world’s fish and shellfish supply is supplied by aquaculture, and scientists have been trying to figure out how to make growing fish sustainable. Many high-value fish such as cobia, sea bream, and striped bass are predators and eat other fish to survive and grow. As a result, their food in captivity is made of a combination of fishmeal and fish oil, and must be caught from the wild to feed them. This is expensive and it further depletes the world’s fisheries.
This makes aquaculture completely sustainable, said Dr Place. 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.
In the study fishmeal was replaced with a food made of corn, wheat, and soy. Fish oil was replaced with soybean or canola oil, supplemental lipids from algae sources, and amino acid supplements, such as taurine.
And, in addition to the benefits already mentioned, raising fish on a vegetarian diet also means cleaner fish to eat, with levels of PCBs and mercury as much as 100-fold lower.
Mercator Media Ltd 2013