Duck hunters are being urged to wear life jackets during the season that starts on Saturday, particularly in areas where water levels are much higher than usual thanks to cyclones Debbie and Cook.
Fish & Game's southern game bird manager for the Auckland-Waikato region, David Klee, said high water levels may cause problems.
"The amount of water around is phenomenal. While water levels have been dropping, there have been places you could usually walk to that may still be inaccessible, or only able to be reached by boat, and some mai mai may be flooded," he said.
"Hunters need to take care around water. Always wear a life jacket when you are on the water, and avoid overloading boats with mates, equipment and dogs."
Water Safety New Zealand agreed that high water levels meant increased risk, particularly in terms of rivers that could be extremely changeable, CEO Jonty Mills saying rivers had been responsible for around a third of all preventable drownings over the last couple of years.