Wild pigs helping to keep bovine TB out of Marlborough
A survey of Marlborough's wild pig population is helping determine the extent of bovine TB in the region.
Pig hunters have been contracted by OSPRI and Landcare Research to hunt in specific areas and collect pig heads for TB analysis since July.
Lymph nodes under the neck of the animal can show that TB was evident in the region.
Pigs contract TB by scavenging dead animal carcasses which have been infected, but do not pass on the disease themselves.
By finding out if a wild pig shot by hunters has TB, OSPRI can then determine that the disease is in the region and present in possums, the main carriers of the disease.
Pig surveillance was the one of the best tools available for understanding the geographical location of TB infection, OSPRI northern South Island programme manager Josh King said.
"When TB is present in possums in an area, it is highly likely that it will also be present in local pigs.
"If we can pinpoint where disease is, we can be specific about possum control."
Since July wild pigs have been hunted across selected areas in Marlborough, as well as North Canterbury, Tasman and West Coast to get a better understanding of the pattern of disease.
The survey is important for the TBfree programme, King said.
The programme is targeted to eradicate TB from wildlife by 2040, farmed cattle and deer by 2026, and across New Zealand by 2055.
Possums are the main transmitters of disease to farmed livestock and to other wildlife.
Much of the work will involve helicopter hunting on private farmland with owners' permission, although some traditional hunting methods with dogs will also be used.
Wild pig heads are collected for post-mortem examination to check for TB in the lymph nodes just below the jawbone to show the presence of the disease in the area where the animal was taken, King said.
It is crucial hunters correctly dispose of skins and offal after they've removed the head, he said.
"Disposing of offal properly is really important for containing any disease a pig might carry."
As more areas of New Zealand are cleared of disease, pigs can also confirm the effect of good possum control, he said.
"The absence of TB in pigs is also useful to show that possum control has been effective and that disease has been eradicated from the area."
Landcare Research Kaikoura field operations manager Grant McPherson said the survey is the final drive to show TB was not in the area.
"It's a new strategy for Marlborough by TB Free to eradicate the disease from the region.
"Pigs are a sentinel species that can be used to show effectively if TB is present in the area."
Hunters have been collecting pigs heads in the Awatere, Waihopai and Wairau valleys.
Using a GPS the specific area where the pig is shot can be later downloaded onto data and used to track if any TB is evident, he said.
Marlborough was almost free of TB and Landcare Research staff were not expecting to find any new evidence, he said.
- The Marlborough Express