Norway's proposal to impose a new 40 percent tax on its netpen salmon farmers will not impact land-based operations, but news of the tax hike may have contributed to a rise in the share prices of several publicly listed land-based salmon firms.

While news of the tax hike sent stock prices of leading Norwegian salmon farming companies such as Mowi, Grieg and Austevoll tumbling, shares of land-based salmon farming companies increased during Wednesday's trading on the Oslo stock exchange.

At the close of trading Wednesday, share prices for land-based farmers Proximar and Atlantic Sapphire were up 3.1