Huon Aquaculture was responsible for using underwater explosives 8,000 times to stop seals from interacting with its fish farming operations in a 14-month period, according to new information released by the Tasmanian Government.
Seal crackers, also known as an "underwater deterrent device", are an approved seal deterrent used to scare them away from fish farm enclosures.
They are explosive charges that are thrown into the water to detonate under the surface.
Monthly seal deterrent usage figures for the period January 2021 to March 2022 show seal crackers were used 8,057 times by Huon Aquaculture — the most of three major salmon farmers in Tasmania.
Petuna used the tactic 1,748 times in the period, while Tassal used crackers 2,259 times.
The documents also show Huon Aquaculture accounted for three quarters of all seal deaths attributable to the three companies.
Eighteen seals died due to interaction with Huon Aquaculture's activities in the 14-month period, while Tassal was responsible for five.
Petuna wasn't responsible for any of the 23 deaths.
According to the documents, a seal death is defined as "mortality caused by an interaction with marine farming activities, operations and infrastructure including but not limited to: entanglement, vessel strike, other infrastructure interaction, deterrent use, sedation, and humane destruction".
Tassal is the only company reported to have also used "bean bags" during the period to deter seals — the lead-filled projectiles used to move seals on from farming areas.
None of the three companies reported using darts, which are usually fired from a shotgun and detonate upon impact with the seal or target.
Of the seal deterrent devices used, seal crackers account for over 98 per cent of devices deployed on marine farming leases.
Huon says it works hard to keep wildlife safe
According to the documents, state-wide cracker usage in 2021 reduced by 62 per cent across the industry compared to the previous year.
Huon Aquaculture's CEO Phil Wiese said the company worked hard to keep local wildlife safe, "however, seals are very intelligent and naturally curious and interaction with farming infrastructure is inevitable".
"It is well understood that higher energy, off-shore sites receive far more attention from seals — they typically feed in deeper exposed waters," he said.
"So they are naturally comfortable in the Storm Bay region where the majority of Huon Aquaculture's fish are situated."
Mr Wiese said the company stopped relocating seals in 2016, more than a year before the state government banned the practice in September 2017.
"We also work closely with the RSPCA in relation to protecting the welfare of both fish and native wildlife, resulting in Huon ceasing to use beanbags and scare caps in 2018," he said.
"The only deterrent used by Huon is crackers — an approved measure under the state government's Seal Management Framework."
The Department of Natural Resources and Environment Tasmania provides and oversees, permits and audits seal management activities.
A spokesperson for the department said there were strict protocols in place to assess applications from those seeking to use seal deterrents.
They said the practices were used to maintain the health and safety of marine farm workers, as well as the seals.
"Seal interactions may also cause loss or damage to fish stocks, and interfere with or damage industry infrastructure," they said.
They said the department's Seal Management Framework aimed to "minimise risks to farm workers while maintaining seal welfare and ensuring full transparency through reporting and monitoring".
Greens call for end to 'barbaric practice'
Under a proposed three-year trial, 50 hectares of Bass Strait, located about 6 nautical miles north of Burnie, will be set aside for fish farming research conducted by the federally funded Blue Economy Cooperative Research Centre.
The Greens have called on the Federal Government to rule out allowing the use of explosives on protected seals during a three-year trial of fish farms in Commonwealth waters.
"Tasmania is potentially on the edge of seeing massive expansion of industrial fish farms in Commonwealth waters," Greens spokesperson Peter Whish-Wilson said.
"Under federal law these seals are protected in Commonwealth waters so the federal government will have a very direct responsibility to the welfare of these animals as well as other protected marine life. So this is an issue the Commonwealth government needs to deal with now."
He said big salmon farming companies should also take the initiative and voluntarily stop the use of seal crackers.
"Most people would find the concept of big salmon companies using underwater explosives or forms of explosives to deter seals unconscionable," he said.
"If JBS [the new owner of Huon Aquaculture] wants to get off on the right foot with Tasmanians then Huon Aquaculture should lead by example and immediately and publicly declare an end to this barbaric practice."
