Posted by: Footler PJ4 SEP 2013
According to the Journal of Fishing and Aquaculture, nearly half the world’s supply of fish and shellfish is now farmed in tanks or ponds rather than being caught in rivers, lakes or oceans. One of the latest developments involves the cobia, a solitary predator usually only taken as bycatch. With its rapid growth rate and high quality flesh, cobia is tipped to become one of the most important marine fish for future aquaculture production.
However, like other high value fish such as the sea bream and striped bass, farmed cobia are fed on fishmeal and fish oils, which are produced from wild-caught fish. Since it can take five tons of wild fish to produce one ton of farmed fish, researchers have been trying for decades to replace the fishmeal and fish oils in aquaculture diets.
Some progress has been made. In Australia, for example, prawn farmers use Novacq, a product based on marine microbes, as a food supplement — with some success. Now for the first time scientists at the University of Maryland Centre for Environmental Science have developed a completely vegetarian diet for aquaculture.
In the vegetarian diet the fish oil, which has become scarce and expensive partly due to its popularity as a health supplement for people, was replaced with soybean or rapeseed oil, lipids from algal sources and amino acids such as taurine. Taurine, found in high levels in carnivorous fish and their prey, plays a critical role in the metabolism of fats, stress responses, and muscle growth. The fishmeal was replaced with a mixture of wheat, corn and soy.
In addition to the potential to make aquaculture more profitable and sustainable, while reducing the pressure on our rapidly depleting wild fisheries, a vegetarian diet also means cleaner seafood with much lower levels of polychlorinated biphenyls (PCBs) and mercury.