Cooke Aquaculture says it lost up to 20,000 salmon from a sea cage on the south coast last week.
The company said high tide and unusually strong currents caused the upset of a cage in Hermitage Bay on Sept. 18.
Cooke officials said cod fishermen have reported catching some of the 10- to 15-pound salmon in their nets, and have found some dead fish along the shoreline.
The company has been licensed by the Department of Fisheries and Oceans to fish for the escaped salmon near the site.
Cooke expects predators, such as seals, will eat the escaped fish that were almost ready to be harvested for sale.
None of the workers at the sea site were injured.
The company said the escaped fish pose no threat to the local environment.