Thieves have stolen more than 400 seal bombs, two dart guns and a shotgun from salmon giant Tassal's Dover facility in the state's far south.
Police said the items were stolen from two locked safes inside a locked shed at the Strathblane facility between April 20 and 28.
The safes were unlocked using keys stored inside a keypad safe on the property.
Police said the 432 explosives, two dart guns and the shotgun were stored correctly, and that their investigation would look at whether appropriate firearms licences were held.
Tassal confirmed that a break-in at its Dover site was discovered on April 28th and immediately reported to police.
The company said the equipment was government-approved and used for dealing with seal interactions and keeping its workforce safe at sea.
Tassal said the aquaculture industry used shotguns to shoot beanbag bullets as seal deterrents, which complies with the Tasmanian Government's seal management plan.
Environment Tasmania's Laura Kelly said the theft was worrying.
"This throws a spotlight on just how violent the industry's attack against seals is," she said.
"We're talking explosives and shotguns, with our recent Right to Information requests showing seals have been shot in the face and 4,000 seal bombs or 'crackers' have been used in the past two years."
A 2018 report by the ABC revealed almost 9,000 beanbag bullets had been fired at seals around aquaculture sites in Tasmania over the previous five years.
Police have asked anyone with information about the theft or location of the stolen items to contact them or CrimeStoppers.
