Ivan Vindheim, CEO of the world's largest salmon farmer Mowi, once again came out swinging for the proposed Norwegian salmon tax during the group's first quarter earnings presentation on Wednesday.

Despite the company hailing an all-time high operational profit of €322 million ($352.9 million), the proposed "resource rent tax" continues to cast a very unwelcome shadow on the country's salmon farming industry and for Mowi.

The proposed tax is expected to be finally approved by the country's parliament before the summer break in June, with a retrospective effect from Jan.