Skretting prepares for sustainable tuna farming

Companies and research teams around the world are near to breeding and rearing bluefin tuna in captivity. Skretting ARC and Skretting have succeeded in developing a feed concept for this much sought after giant fish, reports www.megafishnet.com with reference to Skretting.
For many years, bluefin tuna has been in demand for its exclusive, dark red meat. However, increased demand has led to over fishing and this fish is now considered to be a threatened species.

Since 1997, Skretting Australia has been involved in research on bluefin tuna. Over the past year, Australian fish farmers have been able to conduct commercial farming of this lucrative fish using feed from Skretting. However, the path to this stage has been anything but smooth, as bluefin tuna has a discerning palate.

Karl Sveinsvoll, a researcher in Skretting ARC, says, "The main challenge was to develop a feed with a texture and size that the bluefin tuna wanted to eat, at the same time as containing sufficient and the correct nutrients. This problem was solved by using the feed block concept, Aurora Gel, which was patented in 2003." Sveinsvoll also says ARC and Skretting are currently testing a new generation of feed blocks, which they have called AquaSoft Tuna.

"There are significant advantages of feeding formulated feed to bluefin tuna, as the alternative has usually been to feed them "trash fish", such as herring and mackerel - with a feed conversion ratio up to 20. Formulated feed contributes toward greater sustainability, traceability, less risk of transmitting disease and better control of the nutritional profile of the fish," Sveinsvoll says.

Skretting is also testing the bluefin tuna feed in Japan, Spain and Turkey. So far, the results in Japan have been positive. The trials in the Mediterranean countries have not been as successful until recently when the team experienced a break through in Spain with the new feed. Although Skretting has a feed that the bluefin tuna likes, there are other pressing problems that must be solved before commercial farming of bluefin tuna is possible. Bluefin tuna farming is currently based on wild fish that have been caught and fed until they reach harvesting weight.

"The challenge is to get the fish to reproduce in captivity and to get the fry to survive into adulthood," Sveinsvoll says.

The challenge of "closing the life cycle" is the topic of SELFDOTT (SELF-sustained aquaculture and DOmestication of Thunnus Thynnus), an EU-funded research project, which Skretting ARC, among others, is taking part in.