* Q2 harvest 83,000 tonnes vs guidance of 73,000
* Q2 writedowns in Chile of $115 million
* Says market for salmon "good in Q2"
* Reduced active sites in Chile further in Q2 from 11
* Shares down 1.2 percent, underperforming main bourse index
(Adds comments, share price)
By Aasa Christine Stoltz
OSLO, July 14 (Reuters) - The world's largest fish farmer, Marine Harvest Group, reported a forecast-beating second-quarter salmon harvest and said on Tuesday that demand remained robust.
Norway-based Marine Harvest said it was working to minimise losses in Chile, where it has been hit by fish disease, through a plan which would trigger writedowns of about $115 million in its second-quarter results.
Marine Harvest said it harvested 83,000 tonnes of salmon in the second quarter, up from 76,000 tonnes in the first quarter, and more than guidance of 73,000 tonnes.
Its shares initially rose 2.4 percent before it lost gains and were down 1.2 percent at 4.18 crowns by 0816 GMT, compared with a 1.2 percent rise in Oslo bourse's main index.
"The market has been good for salmon in the quarter," Chief Financial Joergen Andersen told Reuters.
"Prices have been good and our debt has been reduced... from above 7 billion crowns entering the second quarter to about 6 billion crowns," he said.
Salmon prices have risen to 36.10 crowns per kilo in week 27 -- up 36 percent from the same period last year and the highest in three years -- according to data from Statistics Norway.
Revenues from its Norwegian fish farms account for up to 65 percent of Marine Harvest's total sales.
CHILE PLAN
The company, which will post second-quarter results on Aug. 14, said it had approved an updated business plan for its operations in Chile, where it is the biggest industry operator.
Marine Harvest's operations in Chile account for 5-10 percent of its total volumes, down from 25-30 percent in 2007.
The plan aimed to "harmonise the scale of the business to the expected low level of activity in the coming years, and to minimise losses during this period," it said in a statement.
"The plan will trigger provisions and write-downs of approximately $115 million in Q2," Marine Harvest said.
"Marine Harvest Chile will post a negative operational EBIT of approximately 400 million Norwegian crowns ($61.8 million) and a negative financial EBIT of approximately 900 million crowns in Q2," it said.
Andersen said financial EBIT included writedowns of fixed assets in Chile.
Marine Harvest said in April that it had halved its number of active sites in Chile to 11 from 22 during the first quarter.
"We have reduced this (number) somewhat (further) in the second quarter, so it is lower, but not as drastic compared with (the reduction) in the first quarter," Andersen said.
The company said it was in compliance with all financial covenants at the end of the second quarter.
In May, the company raised $47 million in a share issue to finance the restructuring of its operations in Chile and reduce its debt. ($1=6.475 Norwegian Crown) (Editing by David Holmes and Simon Jessop)