Fisheries managers on one of Scotland's most important salmon rivers are calling for a "sensible debate" on whether some birds should be culled to protect fish stocks.
The Dee Salmon Fishery Board said almost three quarters of young salmon are not making it to the sea.
It said this is largely because they are being targeted by predators.
As part of a study, researchers tagged more than 100 smolts and tracked their progress down the River Dee.
They found that 70% from the upper reaches of the river died before getting to the sea.
The study blames predation - birds like the goosander duck taking them from the river for food.
River Director Mark Bilsby said: "When we are losing so many young fish as they migrate down the river, we need to have a really good discussion with the Scottish government and other agencies about how we can protect these further.
"We need to have all the tools in the toolbox to remove these predators."
Some of the birds are already shot under licence but fishery managers now want a "sensible debate" over whether more should be culled to protect the fish stocks.
Fish numbers have been declining on salmon rivers across Scotland for a number of years with several factors at play.
Rising sea and river temperatures, sea lice and an invasion of Pacific Pink salmon have all been blamed.
However, the RSPB is not convinced about the study.
A spokesperson said: " We've not had time to look at the report in detail but we note that it does not conclusively identify predation as the cause of losses of salmon smolts but merely speculates that this is what might be happening.
"A great deal of evidence shows that many environmental factors are affecting salmon populations, of which predation is just one, and we are aware that goosanders and cormorants are already routinely killed on the Dee with the intention of protecting salmon.
"We welcome any informed dialogue that this report generates but we would be very surprised indeed if the authorities decided to increase the killing of native wild predators on the basis of such slim new evidence."
Marine Scotland will meet Mr Bilsby this week to discuss his concerns.
A Scottish government spokesman said: "We take our responsibility to protect the marine environment extremely seriously and the decline in wild fish stocks is a matter of great concern.
"We know a number of complex factors are impacting on wild salmon numbers and that Scotland is one of several countries which have been affected.
"We continue to engage with the wild fisheries sector in efforts to ensure that we are doing all we can to preserve wild stocks including addressing concerns relating to predators."