A survey of by the association Norwegian River Salmon, which represents about 7,000 licenced salmon fishers, said the worst affected rivers are found in Nord-troms, Nordmore and around the Trondheim Fjord. In the rivers Gaula, Orkla and Stjørdals, members report that salmon stocks are 30 to 60 percent lower than in a normal year.
"When fish stocks are down 60 percent in a year, we're on the brink. It's very serious," said association chairman Torfinn Evensen.
He told the Dagbladet newspaper that Norway should consider introducing stricter regulations on fishing salmon this season, and said he believed industrial salmon farmers could be to blame for the decline. If farmers do not properly delouse salmon in the farms, river salmon risk catching lice larvae on their way out to sea, where they then perish, he said.
Fishery and Aquaculture Industry Association spokeswoman Are Kviststad did not agree with Evensen's conclusion.
"There are low numbers of lice in the farms," Kviststad said. "There can be several reasons that salmon fishing is weaker, such as poor access to food in the ocean."