Escaped farmed salmon are threatening stocks of wild fish, conservationists have claimed.
Ecologists are worried about escapes from fish farms
Campaigners from WWF Scotland have urged ministers to introduce more secure cages for the fish.
Almost 630,000 farmed salmon escaped in January this year, when storms battered the coast of Scotland.
But industry body Scottish Quality Salmon stressed the latest WWF report related to Norway and said the January storms had been an exceptional event.
WWF Scotland is calling for minimum cage standards and says the latest research shows salmon in Norway's open waters are at risk from disease and genetic contamination.
According to the study about 500,000 farmed fish escape into Norwegian waters every year, meaning a quarter of salmon or trout found in Norway's coastal waters are fish farm escapees.
The report claims fish are crammed tightly into cages in open water, providing an ideal breeding ground for disease and parasites, such as sea lice.
It says escaped infected fish can then take these diseases with them into the open seas and infect wildlife.
Maren Esmark, of WWF in Norway, said: "It's totally unacceptable that such enormous amounts of farmed fish have escaped from fish farms into open waters, undermining the long-term survival of wild salmon."
A spokeswoman for Scottish Quality Salmon said: "Clearly the matter of farmed fish escapes is of serious concern to salmon farmers, and especially to those who suffered the loss of fish as a result of the most severe weather conditions experienced on the Western Isles for generations.
"However, over the course of the past decade the industry has made significant progress in preventing these sorts of severe weather-related losses.
"Had these storms occurred 10 years ago, the loss of fish and damage to pens and equipment could have wiped out the industry."
Meanwhile, the Esk Disrict Salmon Fishery Board has bought the netting rights on five miles of coastline for £270,000.
The catch from the nets in 2003 amounted to a quarter of the salmon and grilse legally landed in Scotland.
The board believes the buy-out will save some 2,000 salmon, 6,000 grilse and 2,000 sea trout each year, allowing them to return to their home rivers.
Restricted netting will continue for the next three years to accommodate operators working on a lease basis.