Contents of this page

Sandbar Barramundi

The Fish

Feed

Fingerlings

Polyculture

R & D Priorities

Sandbar Barramundi

The trade name for our fish is Sandbar Barramundi. People have asked where the name sandbar comes from. The name refers to a stretch of white sand that appears in the Blackmore River next to the farm at extreme low tides. The tides in the river rise and fall by as much as 8 meters, and when the tide drops below about 4 meters, the mangroves roots are exposed to the air. During the extreme low spring tides the river is only about 20 meters wide and quite shallow. At these times, until the tide turns there is a truce between predator fish and prey fish as they all concentrate their efforts on surviving the very low water levels and use the sandbar as a protective refuge.

Saltwater barramundi (Lates calcarifer) are grown on the farm. These iconic Northern Territory fish are native to the area and thrive in the Blackmore River which is an angler's paradise for barra and many other tropical estuarine fish including mangrove jack, golden snapper and jewfish. Barramundi have a number of characteristics that make them ideal for aquaculture. They are easy to breed , take feed pellets readily, grow quickly and have broad environmental tolerences. From the market point of view, they have wonderful eating qualities,  contain about 2% Omega 3 lipids and can be cooked in many different ways so demand for the fillets is strong. On the farm we grow the fish to about 2.6 kg. This takes about 16 months from stocking 100 mm juveniles.

Barramundi have an interesting life cycle. They breed in salt water, then the juveniles swim into the estuaries (such as the Blackmore River) where they grow to young adults which are all male. When they go to the sea to breed, the bigger fish change from males to females and the cycle goes on.

More information on barra can be found at the NT Fisheries Barramundi site.

Feed

Feed accounts for more than 50% of the costs of growing barramundi, so it is very important that 1) the feed is of optimum quality and 2) the application of the feed is done correctly. On the ARDA-Tek farm we use Australian made feed sourced from Skretting and Ridley. The feed is a floating feed which allows us to monitor very closely consumption of feed so as to eliminate wastage. We feed once a day, keeping the daily consumption to about 10 grams per fish for fish over about 1 kg in size. In this way we achieve about 180-200 g of growth per month. We have found that aiming for maximum growth of the fish by providing the maximum amount of feed that the fish want to eat is not the optimum management strategy.

Sustainability of the raw materials made to produce feed can be an emotional topic. For those interested in facts the NT Fisheries has produced a technical bulletin.

Fingerlings

We purchase 100 mm barra fingerlings from the Darwin Aquaculture Centre. The fingerlings are certified disease free by the Berrimah Veterinary Laboratory and the fingerlings are also inoculated against Streptococcus iniae bacterial disease. We stock about 14,000 fingerlings per ha and usually stock twice a year.

Polyculture

At the ARDA-Tek farm we keep some areas free from commercial production so that we can carry on our R&D programme. Our current R&D work is focused on polychaete worms, local school prawns and local mullet. The worms are discussed in the section on environmental sustainability. The school prawns breed prolifically in the river and huge numbers can be pumped into the ponds at certain tides particularly in September and October. We take advantage of this and grow these prawns which we then feed to the barramundi as supplemental feed. We are also doing some work with the local mullet. The Top End barra fishermen are keen to use local bait, as they are aware that there exists a biosecurity danger in using imported bait. So we are testing a number of species to find one which will prove useful as a bait source for the local fishermen.

R & D Priorities

Priorities are firstly disease management, diagnosis and control: this is top priority simply because disease can wipe out a fish farming operation very quickly: dead fish are worth nothing at all.. The second priority is to optimise the quality of fingerlings from the hatcheries and nurseries: at present there is variation in quality among and between batches and the reasons for these differences need to be researched. The third priority is feed: the aim of feed research is to reduce the cost by using cheaper protein sources, to improve feed formulation, and to understand better the physiology of feed utilisation by barramundi. The fourth priority is genetics, but being number four, let's leave it at that!