"Pleasingly, overall only a small number of relatively minor offences were found, with breaches of the three-shot rule the most common.
"Seven hunters were using guns which hadn't been pinned to restrict magazine capacity to only two shots as required under Eastern Region regulations," he said.
Six hunters at five locations were either using unpinned guns or in possession of lead shot ammunition in breach of the ban on possessing or using lead shot within 200 metres of open water.
Fish & Game rangers also seized a shotgun from another alleged offender in the Bay of Plenty, Garrick said.
Disappointingly, of the offences detected, most were located within the Gisborne and Wairoa districts, he said.
"The circumstances surrounding each case will be considered and actions could include the hunters being prosecuted," Garrick said.
The game bird season for mallards will continue until June 3 for Eastern and Auckland/Waikato regions, and June 16 for Hawke's Bay.
Any hunters planning to harvest game birds are again urged to check the regulations booklet before venturing out.