In the first half of this year, salmon farmers on the Australian island of Tasmania detonated nearly 1,800 underwater explosives to scare away fur seals intent on nabbing fish, government figures show.
Seals are capable of both jumping into pens and biting through pen nets, and they can easily injure or kill large numbers of salmon. Tassal, one of three companies operating farms in Tasmanian waters, reported that seals gained access to its salmon pens some 1,100 times over the past three years.
To ward off the animals, farmers use loud underwater explosives, known as seal crackers. The devices are intended to scare off seals, but they have been known to inflict grave injuries on marine mammals, including burns and broken bones.
Since 2016, Tasmanian farmers have used more than 150,000 crackers, according to data from the Department of Natural Resources and Environment Tasmania. The agency publishes updates on the use of seal deterrents twice yearly in response to a 2022 public records request from the Tasmanian Inquirer.
These updates also include data on the number of seals killed at salmon farms. In the first half of this year, two seals died while entangled in salmon pens; one died after being struck by a boat; and another died during an attempted sedation. (Farmers sometimes sedate seals that enter or become trapped in pens.) Since 2021, at least 48 seals have died at Tasmanian salmon farms.
Tasmania is home to both long-nosed fur seals, which are classified as threatened in the state, and Australian fur seals. Both species are protected in Australian waters. According to the Department of Natural Resources and Environment Tasmania, “The greatest threat to seals comes not from their natural predators, white pointer sharks and killer whales, but from humans.”
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