A die-off of hundreds of thousands of fish at land-based salmon farming leader Atlantic Sapphire has sent shares of land-based aquaculture companies tumbling, with over $258 million (€218 million) shaved off market capitalizations in a matter of hours.

Atlantic Sapphire made up the overwhelming majority of the loss as shares sunk 11.6 percent following the announcement of the losses on the Oslo Stock Exchange, closing at NOK 122 (€12/$14.20) per share, down from the previous day’s close of NOK 138 (€13.59/$16.08).