Three of Norway-based Mowi's Eastern Canada salmon farming sites holding around 2.7 million fish suffered significant mortalities following health treatments, according to the company.

The sites are located at Little Bay, Chaleur Bay and Friar Cove in Newfoundland.

Under Newfoundland and Labrador Department of Fisheries, Forestry and Agriculture regulations, salmon farming companies are required to report "abnormal mortalities" exceeding 10 percent.

Based on the number of fish at the site and the 10 percent reporting threshold, losses at the sites would number at least 270,000 fish, though Mowi did not disclose the total number.