The Manx public is being asked to help protect stocks of salmon and sea trout in the Island's rivers.
This year's river fishing season ended on 31 October and taking fish is now illegal.
The Department of Environment, Food and Agriculture says anyone caught handling, buying or selling illegally-caught fish will face prosecution.
If you spot any suspicious activity on the Island's rivers you should report it to the Fisheries department at DEFA or to any police station. Suspected poachers should not be tackled by members of the public.
Freshwater Fisheries Supervisor Robbie Moore says poaching won't be tolerated as it can severely damage stocks.
He says it cannot be seen as an innocent rural pursuit.