Department of Primary Industries acting director fisheries compliance Tony Andrews said fisheries officers conducted a targeted operation on the Macquarie River, downstream of Narromine.

"Fisheries officers located a camp being used by a number of fishers downstream of Narromine," Mr Andrews said.

"A number of fisheries offences were detected including the use of 41 unattended lines that were set and left unattended, possession of fish illegally taken, the use of 31 live finfish as a lure or bait to take fish on inland waters, the use of a gaff to take fish on inland waters and a master of a boat not preventing a serious fisheries offence taking place.

"Seven people were apprehended by fisheries officers and admitted to the offences when interviewed."

"Seven people were apprehended by fisheries officers and admitted to the offences when interviewed.

"Officers seized 41 set lines, 2 gaffs and 31 European carp and fines totalling $5200 and a number of written cautions were issued to the members of the camp."

Mr Andrews said unattended lines and other illegal fishing gear were prohibited because their use posed a very real risk to the sustainability of native fish populations and other protected fauna."

A maximum of two attended fishing lines were permitted in NSW inland waters, he said.

Attended lines had to be within 50 metres and in the line of sight of the person using the line.

The use of live finfish as bait was also prohibited in NSW, he said, because it presented biosecurity risks to waterways through the potential spread and transmission of noxious aquatic diseases through the transfer of fish from one body of water to another.

Mr Andrews reminded fishers that fisheries officers regularly patrolled waterways to detect illegal fishing activity.

"Fisheries officers are targeted in their operations and if you are doing the wrong thing it is only a matter of time until you are caught," he said.

"Members of the public can also report any suspected illegal fishing activity to the Fishers Watch hotline on 1800 043 536 or directly to your nearest Fisheries office."