WWF Scotland welcomed measures to reduce the amount of by-catch
Scotland's fishing industry is contributing to a "worldwide marine crisis" by throwing back up to a fifth of its stocks, a charity has claimed.
WWF Scotland said that while progress had been made to reduce the amount of by-catch (fish that cannot be landed), ministers must urge the EU to do more.
It wants to see measures to combat the problem included in the Common Fisheries Policy.
The Scottish Government said it had an unrivalled commitment to conservation.
A report by WWF estimated that 40% of worldwide fish stocks, 38m tonnes, is left unused or unmanaged each year, with a "huge quantity" thrown back into the sea dead or dying.
It found that in the North East Atlantic, where fishermen target species such as cod and haddock, up to 20% of the total catch is unused.
It blames factors such as the use of non-selective fishing gear, market demands and quota limitations.
But the charity has also welcomed measures introduced in Scotland to reduce the amount of by-catch, such as the Conservation Credit Scheme where fishermen are "given back" days at sea in return for meeting conservation quotas.
Louize Hill, WWF Scotland's marine policy officer, said: "In order to reduce by-catch further it is important these and other initiatives are rolled out across all European waters.
"We therefore urge ministers to ensure the upcoming reform of the Common Fisheries Policy addresses this issue as a matter of priority."
Rural Affairs and Environment Secretary Richard Lochhead said Scotland works more closely with WWF on fisheries management measures than any other country in Europe.
He said: "Scotland's commitment to the issue of conservation on the fisheries front is unrivalled across Europe. Other nations are encouraged by the decisive and innovative action of our fishermen and learning from their leadership.
"We continue to be very pro-active in generating solutions to radically reduce discards, while discard reduction is one of our key priorities."
The European Commission announced a full review of the EU's Common Fisheries Policy in September 2008, saying the current regime fails to protect fish stocks.
The commission said fishermen who obey the fishing rules are being penalised by the irresponsible behaviour of others who flout them.