More than 600,000 farmed salmon escaped into waters off the west coast during January's storms, it has been claimed.
Ecologists are worried about the ones that got away
Less than 10% are known to have died, according to the Scottish Wildlife Trust and WWF Scotland.
Experts warn the 629,000 fish left alive and free may have a "potentially disastrous" impact if they ended up breeding with wild salmon.
An industry spokesman said fish farms already did all they could to minimise the numbers of escapes.
The storms had been "one in a million" and it was not clear that any cages could have survived unscathed.
Environmentalists stress that wild fish are uniquely adapted to their habitat.
Researcher Laura Bateman said: "While we recognise the social and economic benefits of the Scottish fish farming industry, we believe these should be equally balanced with the socio-economic impacts of the angling industry in Scotland.
"They should not outweigh the importance of protecting Scotland's unique and vulnerable water environment."
She added: "It is important that those involved in the fish farming industry learn from these events."