The River Tay is seen a prime target for poachers

The move, across Perthshire, came at the start of the fishing season in the River Earn.

The operation, involving Tayside Police and Tay District Salmon Fisheries Board, will see officers monitoring activity at salmon fishing areas.

They also aim to carry out specific operations at waterways identified as poaching "hot spots".

The action, dubbed "Operation Salmo", will also see police and the fisheries board regularly meeting to discuss poaching trends.

'Economic damage'

Tayside Police wildlife officer Alan Stewart said there was evidence that poaching was on the increase.

"The River Tay is a prime target for salmon anglers and poaching on a commercial scale, in addition to adversely affecting salmon stocks, has the potential to damage the local economy," he said.

Fisheries board manager David Summers said the problem had not always been properly recognised in the past.

He added: "Numbers of salmon which return from the sea are much lower than they were a few decades ago and there is real concern regarding the future sustainability of stocks."

Meanwhile, the salmon season got under way on the River Forth with a special ceremony.

Stirling Council's fishery service manages a tagging scheme, allowing anglers to catch up to five fish per season.