The escape of the fish, which have an average weight of 550 grams, resulted from a long tear in a net and is the second escape fish loss in the space of nine days for Huon.
Last week it announced that between 50,000 and 52,000 fish with an average weight of 4kg had escaped after a fire on a pen at its Zuidpool lease in the D’Entrecasteaux Channel melted the infrastructure above and just below the waterline.
The second escape was discovered on the morning of December 2 at a pen at Huon’s Yellow Bluff site in Storm Bay. The inner net had a tear from approximately four metres below the surface down to the base of the net.
“Due to their small size these fish are unlikely to survive in the marine environment,” said Huon’s managing director and chief executive Peter Bender in a statement on the company’s website.
“This incident, coupled with the fire at a pen in the Lower Channel last week, is hugely concerning.
“The integrity and structure of the Fortress Pen has not been compromised. While the weather was challenging over the past few days, the sea state was relatively calm.
Weather not the cause
“The direction of the prevailing winds would indicate that weather is not the cause of the net tear.”
Bender said staff had continued working through the night to assess and review the escape, with no clear cause identified.
Internal investigations in relation to last week’s fire are also still ongoing, with no clear cause yet identified.
Over the past few years Huon has invested more than A$100 million in its own patented Fortress Pens, designed for use in Storm Bay and other high energy sites.
“We use lightweight, super-strong nets on the pens (made from the same material as bullet-proof vests) which can withstand extremely high current flow,” said Huon in an article about the cages on its website.
The Fortress Pen System was developed by Huon in response to a need to keep seals out, provide a safe platform for staff to work on and allow the company to farm further offshore.
Tailor-made for Tasmania
“There was nothing available on the market, so we underwent a two-year, new pen development project with funding support from the Australian Government’s Fisheries Research and Development Corporation,” said Huon.
The pens contain no steel parts to damage boats or chaff through nets and ropes.
A key feature is a patented, wide-style stanchion with flexible seal fence posts in an angled socket to allow an outer predator net to be set around the inner net while keeping a distance of between 2m and 7m separation between the nets. This outer predator net is connected directly to the sinker tube to reduce rigging and keep it tensioned at all times and in all weather.
A tensioning system for the inner net allows it to flex with the pen, the predator net and the sinker tube.