Poaching could pose a serious threat to a valuable resource in Manx waters.
It is the time of year when newly reared trout and salmon are released to replenish stocks.
There is only a slim chance of survival for the salmon anyway, and in the past poachers have assisted in their demise.
John Ballard from the Fish Hatchery at Ballaglass is urging people not to buy salmon offered to them, and instead report anyone trying to sell their illegal catch.
He explains why salmon stocks are so precious: