The Glenomaru Reserve in the Catlins has been closed to recreational hunters for three months from July 1 while the Department of Conservation (Doc) works to bring the area's increasing feral pig population under control.
Doc area manager Robin Thomas believes the pigs - a kunekune-domestic crossbreed - were released in the Glenomaru Reserve deliberately by hunters wanting easy sport.
The pig population is causing problems for local farmers who are having to repair damaged fence lines and re-sow pig-rooted grazing paddocks.
Glenomaru farmer Chris Roughan has also expressed concern about the feral pig population potentially spreading tuberculosis to other animals on his property.
The population was growing rapidly because the pigs were such prolific breeders, he said.
"A sow can have a litter at three months, then they can breed three months later. I've seen litters of up to 10. Wild pigs don't have litters that size."
"We are not the only people having this problem, but we've decided to get together with the Animal Health Board and Doc to do something about it."
Mr Thomas said in earlier recent years there had not been an issue with pig numbers, but in the past three years there had been an upsurge, and this had come from a domestic crossbreed he believed was released for sport.
Anyone found releasing the animals could be prosecuted by Doc and fined up to $50,000 or face a term of imprisonment.
Doc had organised reputable hunters and pig traps to try to bring the population under control, Mr Thomas said.
"It is very hard to know exactly how many are there ... there are quite a number there, and a reasonable number have been taken out already.
"These pigs have caused significant damage within the reserve, as well as the adjoining farmland."
They were turning over the ground for feeding stock and creating a problem for farmers around lambing time, he said.
Farmer Nathan Wilson, whose property is on Matuanui Rd, said his farm was not on the boundary of the reserve.
"When they were in the reserve, they weren't affecting me, but the pigs have spread from the reserve into the Katea Valley."
While the pigs weren't costing him anything yet, their rooting was making a mess and he had a few repair jobs to do, he said.
Puerua Valley Rd farmer Howie Gardner said he had heard all sorts of stories about people releasing and feeding pigs, but had no first-hand knowledge of the issue.
"One of the biggest problems is the pig hunters. The numbers [of pigs] that come out this way are not high. At the moment there are more hunters than pigs."
Mr Roughan said tuberculosis was a major issue, but the pigs were also costing him money damaging grazing and fencing.
Anyone found releasing pigs needed to realise they would be prosecuted, he said.
"There are laws in place ... that needs to be spelled out loud and clear."
