It sounds too good to be true: A common marine species that consumes microorganisms and can be converted into much-needed feed for salmon or a combustible biofuel for filling petrol tanks. And it can be cultivated in vast amounts: 200 kg per square meter of ocean surface area. Other than the Japanese and Koreans, who eat tunicates, no one has paid them much attention until now.
Tunicates (ciona intestinalis) is the name of this unexpected source of such rich potential. The species is the starting point for a research-based innovation project being carried out by researchers and innovation specialists in Bergen. The idea was hatched by a group of researchers at the University of Bergen and Uni Research.
The yellowish, slimy growth that many of us have come across on ropes that have lain in seawater is the marine organism known as tunicates.
Tunicates are basically living filter tubes that suck bacteria and other microorganisms into one end and excrete purified water out the other end. This is how tunicates feed – at the very bottom of the food chain and without competing directly with fish or other marine animals higher up in the chain. At the same time tunicates clean the fjords and coastal areas.
The fact that tunicates also are the only animals that produce cellulose – and that they are rich in omega-3 fatty acids – make them a potential alternative for bioethanol and as a feed ingredient for farmed fish.
From cellulose to bioethanol
The tunicate is the only animal known to produce cellulose, with which it constructs its body wall, called the mantle.
Breaking down cellulose yields sugars that can be used to produce the fuel bioethanol. Much of the world’s bioethanol currently comes from corn, a controversial source since this crop could be used to feed people instead.
One alternative being thoroughly researched is to produce bioethanol from the cellulose in forest-based biomass. But this is not unproblematic either, since the biopolymer lignin contained in wood is valuable in many other applications. Tunicate cellulose would be a less controversial source because it does not contain lignin.
Targeting fish feed based on marine ingredients
Even more attractive than biofuel production is the use of tunicates in feed for salmon and other farmed fish. Norway is the world’s largest producer of salmon feed, and there is a huge demand for more marine proteins as feed ingredients, but the limit has already been reached in industrialized fishing.
Norwegian fjords could sustain tunicate farms that produce 100 times more protein by surface area than any land-based protein cultivation. Pictured are tunicates raised at a research facility in Øygarden, Norway. (Photo: Bård Amundsen)
One major challenge facing feed producers is to produce salmon feed containing omega-3 fatty acids, which the fish need but do not generate. The bulk of omega-3 in salmon feed presently comes from the fisheries industry. Dried tunicates contain 60 per cent protein and are rich in omega-3. Perhaps just as importantly, salmon find them tasty as well.
Read the original article by the Research Council of Norway here.
Text modified by: Thor Lanesskog, ThorNews