Marine Harvest, the world's biggest Atlantic salmon producer with sizeable operations in Scotland, has forecast a sharp fall in 2013 volumes because it will have fewer live fish ready for slaughter.

The company warned earlier this month of an 84% drop in earnings, and yesterday it reported third-quarter results which prompted a 5.6% fall in its shares on the Oslo stock exchange.

Marine Harvest's earnings before interest and taxes in the quarter to September 30 fell to 73 million Norwegian crowns from 457m crowns a year ago (£46m to £7m).

It also unveiled plans for an £85m investment in Norway to keep production costs low in the face of rising feed prices.

Marine Harvest said it expects the full-year harvest to be 390,000 tonnes of gutted weight, up a touch from an earlier forecast of 380,000 tonnes, but sees volumes falling to 350,000 tonnes next year, which analysts said was below expectations.

However, the company said supply growth was likely to "flatten out" in Europe in 2013, and prices were expected rise to help offset the fall in volumes.

Chief executive Alf-Helge Aarskog said: "If supply and demand is at work, we will see an increase in Europe, but America will lag a few quarters."

The company, controlled by shipping tycoon John Fredriksen, said that it is ready to take advantage of opportunities arising from the financial difficulties its rivals are likely to face at current price levels.

Its Scottish facilities include four freshwater loch sites, five hatcheries and 25 sea farms.