New Pellet For Farmed Bluefin To Cut Costsff

A development in research for food pellets for farmed southern bluefin tuna may halve the industry’s feeding costs for labor and running the boats.

From experiments on yellow tail kingfish the new pellet has been found as effective as the pellets currently used for tuna.

A problem with the pellets used now is they are high in moisture so they are not stable at air temperature and must be stored frozen to prevent mould.

“This need for freezing greatly increases transport and storage costs. It also limits the use of labor saving automatic feeders,” South Australian Research and Development Institute (SARDI) senior scientist - tuna, Jeff Buchanan, said.

“All these issues restrict the use of pellets by commercial farmers.”

The next step will be to test the feed on tuna and this will go ahead when funding becomes available, hopefully in autumn this year.

If this is successful, testing on a pilot scale - involving one or two cages - may go ahead next year.

“The big improvement is if they grow well on this you might take the boat out every third day ... now they’re going out twice a day,” Dr Buchanan said highlighting the high cost of diesel. “It may save 50 per cent on feeding costs, not the cost of the food, (but) the labor costs and running the boat.”

SARDI produced three pellet diets involving a control (the regular pellets) and two others containing a different preservative each, enabling them to be stored at room temperature.

A 50-day growth experiment using kingfish found one of the pellets containing a preservative (based on propionic acid) worked the same as the regular pellets, while the fish did not eat much of the third pellet.

“This stabilized diet has shown strong promise with the surrogate species but this now needs to be tested on SBT to see if SBT will respond the same way in terms of intake and growth,” Dr Buchanan said.

“Ideally the stabilized pellet should be tested in combination with automatic feeding systems to maximize the benefits as, if successful, it might only be necessary to top up on site feed hoppers every two to three days rather twice daily trips.”

Improving tuna pellets is one aspect of a broader Aquafin CRC research project on tuna nutrition lead by Dr Robert van Barneveld.