More than 11,000 salmon have escaped from a fish farm in Argyll and Bute.
The salmon are believed to have vanished into local rivers around the farm at Geasgill, near Ulva.
Only 250 of fish have been accounted for and fishermen have been ordered to kill any they find.
The cost to the Scottish Salmon Company is unknown but a similar escape in 2015 totalled £240,000.
The Scottish Gamekeepers Association (SGA) has raised concerns about the impact on the local wild salmon population.
The SGA’s Greg March said: “We can continue to catch and dispatch as many of the escaped fish as we can but the damage has been done because lots won’t be caught.
“Those on the environmental side in Scottish Government need to raise greater awareness of the dangers to wild fish caused by escapes from fish farms and start doing something more effective about it.”
The escape was discovered during what the Scottish Salmon Company called a “routine fish-handling exercise”.
“This was reported to Marine Scotland and investigated in line with standard procedure,” a spokeswoman said.
“We take the health and wellbeing of our fish and the surrounding environment very seriously and have reviewed procedures and training.”