The shark's presence in the lake went viral early this month after local fisherman Clinton Bambach filmed it swimming near Murrays Beach jetty.

There have been several other sightings but none quite as spectacular as Rod Collins, of Kurri Kurri, who filmed the juvenile shark jumping out of the water off Pulbah Island.

However, a sighting last week with a hook in its mouth with line and lure trailing has confirmed Mr Bambach's fears that someone would try to kill or capture the shark after his footage was released.

Shannon Malone from Fishermans Warehouse Tackle World at Marks Point said he had heard of many sightings of the shark and several lately confirming it had a hook in its mouth.

It is an offence to harm a threatened species - including a great white shark - with a maximum penalty of $55,000 or one year's imprisonment or both.

■ Phone 1800 043 536 if you see the shark or anyone harming it.