On the Atlantic Salmon Trail

An opportunity to investigate the supply chain of Atlantic Salmon with Tasmanian producer Petuna offers insight into the many players needed to bring Australia’s favourite fresh fish to our tables

By Catherine Norwood

Viewed from the outside, there is barely a hint of the fervent activity underway within the walls of Skretting Australia’s aquafeeds plant, which lies on the eastern outskirts of Hobart. Inside staff are busy with the mixing and milling, pressing and pelleting of various animal and fishmeals, oils and grains, preparing more than 90,000 tonnes of feed to exacting formulations for Australia’s burgeoning aquaculture sector.

Most of the ingredients come from Australian producers – grain from our farms and animal byproducts sourced from domestic meat processors.

As a lab technician at Skretting for more than two years, 23-year-old Georgia Eastburn has become accustomed to the smell. This is her first “real job”, she says, after completing her Bachelor of Applied Science with a major in aquaculture. She is one of 76 staff onsite.

She is responsible for testing each batch of aquafeed to make sure it meets the specified nutritional content, and providing quality control for the various formulations that cater for different fish species and various stages in fish life cycles.

Tasmania’s Atlantic Salmon and Ocean Trout producers take by far the largest share of Skretting’s product. Petuna, along with Tassal and Huon Aquaculture, accounts for almost 60,000 tonnes of the feed, also buying from other manufacturers. Bulk deliveries head by the semitrailer load to hatcheries and fish farms from the top of the state to the bottom.

Building boom

As aquaculture has expanded, apprentice boilermaker Clint Riley is taking advantage of the boat building boom it has generated.

Across the River Derwent, south-west of Hobart, is the deep-water port of Margate, which is the base for the shipbuilding operations of Haywards Steel Fabrication and Construction. Sparks fly in the workshop as two giant skeletons take on a boat-like shape – the latest in an ongoing stream of orders for new vessels from the three salmon producers. The vessels range from 25 to 35 metres and cater for live-in staff who provide around-the-clock monitoring of operations, as well as controlling the feed distribution for fish at sea.

The managing director of Haywards, Steve Edmunds, says the expansion of the aquaculture industry has allowed the business to double its shipbuilding staff in the past three years, adding tradesmen, apprentices, naval architects and project managers. The firm has 280 staff members, a quarter of whom are involved in shipbuilding and maintenance.

He says only three or four new vessels are completed each year, depending on the size, and the additional staff capacity is expected to cater for the aquaculture sector’s long-term plan to double Atlantic Salmon production from almost 50,000 tonnes in 2014-15 to 100,000 tonnes by 2030.

At Haywards, 28-year-old Clint Riley is among those benefiting from the shipbuilding boom. The former printing machinist is retraining in a career he sees as having a better future. He began working at Haywards’s Wynyard workshop, near Burnie, as a trade assistant more than two years ago, but in January became an apprentice boilermaker and welder at the shipyard.

It is not far from Margate to the fish farms of Tassal and Huon Aquaculture in the D’Entrecasteaux Channel. The two firms also have farms at Macquarie Harbour on the south-east coast, although Petuna is the longest-standing and the largest leaseholder at Macquarie Harbour, which is serviced by the remote community of Strahan, population 660. Aquaculture has provided a lifeline for the town, which has suffered from downturns in the mining and forestry sectors. 

Petuna has 53 staff at its fish farms on the harbour, 46 of whom are based in Strahan. Then there are the contract service providers such as Strahan Dive. Dive operator Tim Richards, 51, is a former miner who made a career change more than a decade ago, with aquaculture in his sights. Strahan Dive now has 12 employees, providing commercial dive services that include underwater inspection and maintenance for Petuna.

As part of a four-person dive team that includes a diver, standby diver, supervisor and dive attendant, he heads out on to the harbour to inspect the nets on Macquarie Harbour. The team checks for holes, removes dead fish, inspects the hulls of vessels and casts a critical eye over the underwater environment and seabed.

Tim Richards says Macquarie Harbour is a unique environment, with a layer of black freshwater overlaid on seawater, which can make diving a challenge. It can be pitch black below the surface, and in winter pockets of freshwater along the shore can freeze. Sometimes the team members have to break their boat free of ice before heading out to the leases, where the water will be a comparatively warm 10ºC or, in summer, a balmy 20ºC.

Tim Richards provides commercial dive services including underwater monitoring and maintenance for Petuna.

The freshwater layer is also what makes the harbour so attractive for fish farming. The potentially fatal amoebic gill disease is one of the most significant health issues for the industry in Tasmania. Bathing fish in fresh water cures the condition and, as a ‘self-treating’ environment, the harbour is free of the disease.

Monitoring of fish health and research into disease control is ongoing, with the Tasmanian Government’s Animal Health Laboratory (AHL) at Launceston leading the way. The AHL tests an average of 3000 fish a year, conducting approximately 10,000 tests for the Tasmanian Salmonid Health Surveillance Program, which is funded jointly by industry members and the Tasmanian Government.

The AHL has 22 full-time staff. While it provides diagnostic services to all primary production sectors in Tasmania, about half of its work is tied to aquaculture. Research microbiologist Emily Spencer, 32, has been working at the AHL for two years and recently joined a new three-year, $3 million research program funded by the FRDC, developing vaccines to counter emerging Atlantic Salmon viruses. The research team includes nine full-time staff.


At Petuna’s hatchery, based in Cressy in northern Tasmania, the success of AHL programs to develop vaccines against a range of fish diseases has significantly improved fish welfare, according to site manager Shaun Slevec. From as many as six baths for disease control, fish might now undergo only one or two treatments during their life cycle.

Microbiologist Emily Spencer is working on new vaccines to protect Atlantic Salmon from emerging disease issues.

The Cressy hatchery is where production officially begins for Petuna, which has its own broodstock but also sources some from Saltas, a hatchery jointly established by Atlantic Salmon producers and the Tasmania Government. 

Shaun Slevec says light and temperature controls are used to stagger hatching and growth rates to provide consecutive waves of maturing fish, for year-round production of a consistent product, “because the market wants the same fish, every day”

Feed is the major input, but at the hatchery there are also significant water and power inputs. The fresh water supplies that provide a home for hatchlings for the first 12 to 18 months of their lives come from the Great Lake in the heart of Tasmania’s Central Plateau. It is delivered via the same gravity-fed irrigation system that supplies district farms, and faces similar restrictions in the event of drought. 

Petuna has cut its fresh water use by 95 per cent with its recent investment in new recirculating aquaculture systems (RAS) at the hatchery that help to manage the drought risk. However, six-figure power bills are the norm, with energy required to run the RAS and keep water clean and control water temperatures for the fish (between 2.5ºC and 10ºC).

It takes up to 18 months from the production of eggs for the fish to reach ‘smoltification’. This is the physiological process that allows fish to process and eliminate salt from their bodies and signals their readiness to move from the freshwater hatchery to estuarine or ocean waters.

Migration to sea

As winter approaches and fish become physically ready, an “assisted” migration process begins. For Petuna, mid-April marks the start of this process, and specially fitted, oxygenated tanker trucks begin transferring live smolt cargo from the hatchery to Petuna’s fish farm on the Tamar River. In July, transfers begin heading south-west from Cressy to the Macquarie Harbour leases, until the stocking window closes in September. 

The challenge, says contractor G&D Transport’s Tony Dyke, is to deliver all the smolt within the required timeframe, particularly through the mountainous trek from Cressy to Strahan. Of his 15 staff, 10 work almost full-time making deliveries for Petuna, including feed deliveries. 

His company has five 25,000-litre tanker trucks for smolt, as well as four 30,000-litre tankers for harvested fish. The smolt tankers carry 1.8 tonnes of fish at a time, moving up to three million smolt each year for grow-out. The harvest tankers can carry up to 13 tonnes of fish at a time from the marine farms to the factory for processing. 

At Macquarie Harbour, G&D’s tankers are a common sight out on the water, on board Petuna’s barges, where they deliver smolt directly to their new homes. Water from the harbour is mixed into the tankers to help acclimatise the smolt before they are transferred directly into the floating pens,  where they will spend the next 12 to 18 months.

Petuna targets an average size of 3.8 kilograms for its Atlantic Salmon. Harvesting is essentially the reverse of the tanker system that delivers the smolt, although it occurs continuously throughout the year, with peaks at Christmas and Easter. 

Harvest tankers are driven onto barges at Strahan, sometimes two abreast, and shipped out to the pens, where the fish are taken straight from the water and killed quickly with a single blow direct to the back of the head. They are transferred to the tankers and, in fewer than 40 seconds, chilled in ice slurry to below 3ºC for the three-hour trip to Devonport for processing. (The Australian design for the tanker transfer system has since been patented and sold to Norway.)


Petuna has recently upgraded its Devonport processing facility with a $9 million expansion that has doubled its previous processing capacity and provided more employment. There are now 110 full-time staff at the site, in production, maintenance, quality and administration.

The upgrade includes investment in new European-built automated gutting and filleting equipment, but local expertise plays a major role in ongoing refinements to improve the connections and workflow efficiencies for staff and equipment. 

As the manufacturing and design manager of the fabrication division of Tasmanian company Degree C, Trent Madden is a regular visitor to Petuna’s processing plant, fine-tuning everything from the supply of cleaning water to the fabrication and operation of conveyor belts carrying the fillets between machines and out to dispatch. After 15 years working with Petuna, he says the evolution of its operations means there is almost more superseded equipment in the company’s ‘graveyard’ than there is in the processing plant.

Also in Devonport, James Wescombe of MGP Tas Pty Ltd is part of the support team for the processing plants of Petuna and Huon Aquaculture. Thankfully, late-night calls are rare, he says, but they are part of the 24-hour service he offers for the maintenance and replacement of electric motors to keep processing on track. 

At Petuna’s factory, for instance, he estimates there are more than 100 motors that keep pumps supplying water and the conveyor belts turning on the processing and packing lines. The company’s operations are based on processing fish within 24 hours of being harvested.

“If something breaks down late in the day, which can be 9pm or 10pm during the busy periods, it needs to be fixed overnight, so processing can begin again for the morning shift, which might start at 5am or so,” he says. Aquaculture is not the only sector that uses MGP’s services, but James Wescombe says the sector’s support was important when he went out on his own to establish the business three years ago, with a staff of three.

To market

Petuna sells about 20 per cent of its fish wholesale, head on and gutted (HOG), and 80 per cent are further processed in some way into ready-to-use products such as fillet portions. Recent contracts with supermarkets have increased the proportion of higher-value consumer ready-to-eat products over the wholesale HOG products.

Petuna also has a traditional smokehouse onsite, using both hot and cold smoking techniques to further value-add, a process that can take up to 36 hours to produce a finished product.

In the Devonport deli of the gourmet grocery chain Hill Street Grocer, Petuna’s products are prominently displayed. Store manager Trudi Beveridge says it is sometimes difficult to get regular supplies of the wild-catch fish her customers like, such as Pink Ling and Blue-eye Trevalla. “But the Atlantic Salmon is always a popular choice, because it’s a consistent, quality product, and it’s always available. And there’s also a perception of freshness,” she says.  

These are key factors behind the consistent, double-digit growth in consumer demand for Atlantic Salmon across Australia. From his base in Melbourne, where he is general manager of Fresh Freight Tasmania, Michael Leonard and his team oversee the distribution of much of Petuna’s product. He coordinates transport from the Devonport processing plant via the Spirit of Tasmania or SeaRoad shipping to Melbourne, and on to further destinations. 

He calculates total aquaculture sector sea freight might be worth more than $25 million a year. For his company alone, it underpins the jobs of 93 employees and another 60 contractors in Tasmania and Melbourne.

Overall, it is estimated that as many as 5000 jobs are directly related to Tasmania’s Atlantic Salmon industry, which contributes $1.2 billion to Tasmania’s economy, according to a 2015 report from accounting firm KPMG, with additional value further afield. Not only is it sold in every supermarket and hundreds of seafood specialty stores, it also features somewhere on the menu of many a restaurant and cafe.

In terms of fisheries, the aquaculture industry has made Tasmania the nation’s most-valuable producer of fish and aquaculture producer of sh and aquaculture products. In 2014- 15 salmonids (both Atlantic Salmon and Ocean Trout) represented 30 per cent of total Australian seafood production, both farmed and wild caught.

That figure is only expected to grow as the industry increases production capacity and as consumers turn to Atlantic Salmon in increasing numbers. In May this year, Woolworths managing director and chief executive o cer Brad Banducci suggested more customers were opting for salmon as an alternative to red meat, given high beef and lamb prices this year. “We are seeing a movement in protein from red to white and pink meat – chicken and salmon – because they are more affordable,” he said.

It seems clear that the ripples of salmonid in influence are steadily changing both the economic fortunes of Tasmania and the dining habits of the nation.

More information


Tasmanian Salmonid Growers Association