Millions of Atlantic salmon are filling 18 super-tough ‘fortress pens’ at a new farm site in open water in southern Tasmania.
Younger, smaller fish, up to half a kilo in weight, are going to sea at Yellow Bluff — 2.2 million of them.
They are transported from the company’s hatchery, pumped into the well of boat the Ronja Huon, and taken to the fish farm site.
“After about eight months they’ll be transported to larger pens at Storm Bay,” said David Moorehead, general manager of Huon Aquaculture’s marine operations.
It allows the company to keep the different sizes separated in different locations.
“It also allows us to fallow Yellow Bluff before we then stock it next year,” he said, a move expected to help protect against disease.
Last year the company lost salmon in Storm Bay to the virus pilchard orthomyxovirus (POMV).
Huon Aquaculture is currently harvesting 90 to 100 tonne of fish a day, while the company itself is growing 10 per cent annually.
White water breaks over the pens
Working out at Yellow Bluff, and in the even more open water at Storm Bay, is not for the faint hearted.
The farms can face the full brunt of southerly seas and weather.
“If the swell is over two or 2.5 metres, that can restrict us,” Mr Moorhead said.
In May 2018, seas reached heights of 6 metres at the open waters of Storm Bay in Tasmania’s south-east.
The special fortress pens are designed to withstand rough weather and keep seals out.
It is a two-net system — a tough outer net and an inner net — with about two metres between them.
But despite the tough design, breakages did occur in 2018 when the company lost more than 100,000 fish.
Seals a constant challenge
Mr Moorhead said Huon Aquaculture had been working on the nets ever since and had reinforced their pens with extra ropes.
“We did have feed bins in some of those, so we’ve removed those and we’re feeding via barges,” he said.
“We did change all our pens to be double netted [and] that’s seen a dramatic drop in the seal activity that we’ve got around our pens.”
It is usually when nets are damaged by boats or equipment that seals slip through for an easy feed.
Occasionally the company will use firecrackers in the water to scare seals away.
Two other big Atlantic salmon farmers
The Yellow Bluff site, north-east of Bruny Island, is a key part of Huon Aquaculture’s grow-out plan for Atlantic salmon.
Mr Moorhead said the process started with approval applications in 2016.
With those approvals in place, the moorings and the fish pens have been established and the fish were moving in.
But Huon is not the only aquaculture company to be setting up in more open water in Tasmania’s south-east.
Petuna’s application for its fish farming expansion in Storm Bay has had some of its early approvals, and aquaculture giant Tassal has had four 45-hectare leases approved.
Tassal’s farms will be at a site known as West of Wedge near the Tasman Peninsula.
A spokesperson for Tassal said the site was among the highest energy conditions in the world, and the company was focussed on responsibly transitioning salmon production to the farm.
It is not known when Tassal will set up its farm site or start putting fish in the water.