The tuna industry is intricately orchestrated to coincide with the natural movements of the SBT, value adding to this natural resource at every stage, competing against the rough waters of the Great Australian Bight, and the Southern Ocean. Success is achieved through coordination, innovation and teamwork, with each step relying on the successful completion of the one prior. Years of experience, research and attention to detail feed into the practice, yielding world class, premium quality product. The majority of Australia’s catch is caught for tuna ranching using purse seine nets which target surface schools of SBT. The remainder of SBT are targeted or taken incidentally by pelagic longline vessels in the Eastern Tuna and Billfish fishery, and to a lesser extent, the Western Tuna and Billfish fishery. The tuna ranching process is described below.
Typically it all starts with the spotter plane. Flying above the Great Australian Bight, a pilot searches for schools of tuna. Using an expert eye they estimate the average size of the tuna and the quantity, attempting to identify which patch will be the most promising. The information is relayed to the skippers of the tuna boats who prioritise which schools they target, ensuring efficient travel, size of fish and size of school, ensuring we minimise our costs of production whilst maximising returns.
If all is going according to plan, a third boat, known as a towboat, is called upon. The role of the towboat is self-explanatory; it carries a tow cage used to transport tuna. Skilled skippers and crew align the tow cage alongside the purse seine net such that the gates on each net match. The seiner boat pulls in their net slowly, encouraging fish to naturally transfer from the fishing net to the tow pontoon with low stress. Specific schools are targeted, the purse seine method is generally size and species specific, resulting in minimal by-catch. Contact by the fishing gear with the seafloor is very rare.
Once the tow cage has approximately 10-15,000 fish the gates are dropped. With the tow cage attached and tuna inside, the towboat travels back to Port Lincoln. In the waters behind Boston Bay await static tuna cages into which the tuna must be transferred. An independent auditor manually counts each individual fish, determining the number that is in each cage. By multiplying the number of fish by the average weight the company knows how much of its quota it has caught, and thus how much they are yet to catch.
The prized Southern Bluefin Tuna are fed a diet of baitfish over a period of 4 to 5 months, during which time the fish grows, maximising its colour, texture and flavour. The aim is to double the weight of the fish. Additionally, as winter approaches, the waters cool and tuna begin to build up fat. It is these fatty reserves that are celebrated in the world of sashimi. Harvesting of the tuna is swift with unparalleled attention to detail. The aim is to minimise stress in the fish since upon stress lactic acid is released into the tuna’s system, which influences the flavour of the fish.
By reducing the stress felt by the fish, the quality and the integrity of this product is maintained to the highest standard. Divers manually capture individual fish and guide them onto platforms that lead to the deck of the boat. Within 10 seconds of being out of water the fish are euthanised humanely using the “iki jime” method. This has been perfected over time to minimise stress. Tuna are immediately transferred into an ice slurry or refrigerated sea water in order to keep fish fresh. The speed of the process maintains premium quality.
