The pork industry says about 20,000 to 30,000 fewer pigs are being slaughtered compared with previous years.
That is causing some problems for a butcher in Lower Hutt who is trying to find legs of pork of the size his customers prefer as Christmas hams.
New Zealand Pork says domestic pig farmers cannot compete with high feed costs and imported products undermining prices and some have stopped producing.
Chair Ian Carter says that while there's usually a shortage around Christmas, fewer pigs being slaughtered will make that worse.
Craig Taylor, who owns Taylor Quality Meats in Lower Hutt, says he may have to buy bigger legs that will cost customers more.
He says it will pay this year to order well ahead to secure a ham.