Peter's Blog

Tuna harvest under way

Mr TRELOAR (Flinders) (15:31): I rise today to talk about something I was very pleased to be part of last weekend and something I have been meaning to do for a long time—that is, to go out on a boat off Port Lincoln to be part of the tuna harvest. Last Sunday at 6am, I had permission to board the Challenge. My thanks go to Graham Tapley, his son Joe and also Chunky Bryant, who had me on board for the morning. We left the wharf at about 6am and steamed out for about an hour to the other side of Boston Island where we pulled up next to a service vessel that was tied to the tuna ring. The five divers were already in the water and about to start work.

The southern bluefin tuna quota in Australia consists of some 5,665 tonnes. I understand that 96 to 98 per cent of that is owned and held in Port Lincoln and that 96 to 98 per cent of what is held in Port Lincoln is farmed—the term sometimes used is ‘ranching’. The southern bluefin tuna enter the Great Australian Bight in the latter months of every year, having arrived from the Indian Ocean some 3,000 kilometres away. Southern bluefin tuna inhabit all the southern waters right around the globe but, interestingly, the Great Australian Bight is the only place in the world where the fish aggregate at the sea surface, which makes it possible for the schools to be captured via purse seine.

This occurs in December, January and February. Everybody is well aware of how important tuna is to Port Lincoln and South Australia. It was made famous by Colin Thiele’s book Blue Fin and is celebrated each and every year on the long weekend in January at Tunarama. Interestingly, this aggregation in the bight annually during December, January and February happens to coincide with the southern bluefin tuna moving into their fastest growth rate, so the aggregation and capture coincide exactly with the fastest growth rate.

Once they are towed in within these purse seine nets and deposited into the tuna rings or tuna farms, they are at their best growing rate. They are fed each and every day with pilchards or sardines, depending on which school you went to; 80 per cent of those sardines are caught locally and the other 20 per cent are imported. The sardine quota is an interesting one. It is Australia’s largest fishery, with some 42,000 tonnes at the moment and, as I said, it is mostly fished in the gulf just to the west of Eyre Peninsula. The fish are held in pens and fed for about three to six months and then harvested, and that is what I took part in on Saturday. That harvest is drawing to a close.

It is incredibly labour-intensive do. There are divers, and there would have been around 20 men involved in the whole process. The divers capture the fish individually. They catch them by the tail, roll them on their side, and that tends to nullify the fish, and then they steer them slowly to the edge of the pen, where they are placed on a conveyor belt that carries them up to the boat, where they are spiked, cored, wired, bled and gutted, and within a couple of minutes they are dropped into big tanks of cold sea water.

Sea water freezes at below zero, so the sea water sits at about zero degrees. The fish are dropped in it gutted and bled, as I said, and they are kept there for the period of time that the harvest continues; my guess is that it is around three hours. It is then steamed back to shore, unloaded, transported and frozen to minus 65 later that day. Minus 65 is a critical temperature because it is from that temperature that they can be thawed and be at their best.

About 20 per cent of the harvest occurs later in the year, when they are sold directly to Japan as fresh fish. Japan makes up almost the entirety of the market. In some ways, that makes the fishery a little vulnerable, but they are actively seeking other markets in Asia, but Japan is culturally suited to eating the sushi that comes from fresh tuna. One of the challenges going forward will be how to best manage and account for the recreational catch, certainly a little bit in South Australia but particularly out of Portland in Victoria. This is something that the industry and the federal fisheries minister are looking at closely.