Twelve-gauge ammunition and shotguns remain more popular than 20-gauge, and steel shot - more environmentally friendly - is the dominant ammunition sold.
Lead shot is banned in 12-gauge shotguns over open water.
He said decoys had seen a lot of changes in the hunting industry, with the variety on offer hugely increased.
He pointed out a large Canada goose decoy, complete with bobbing head to imitate feeding.
"In the American market, there's quite a variety over there, we see the consequences of that here."
But there is also New Zealand's unique decoys, including paradise duck male and female pairs.
Some decoys are remote-controlled, including a pair of ducks on poles appearing to land, with whirring cardboard wings making a realistic sound.
Mr Roseingrave said he was a "baby-boomer" hunter and thought numbers had fallen off over the years.
However, this year it felt as if more of the younger generation were participating.
Mr Roseingrave likes the comradeship that hunting provides.
The Wellington region season runs until June 15.