TBfree Southland

Southland has seen a gratifying drop in the number of TB infected herds from 56 in 1995 to only two today. This success is the result of a number of factors:

• The identification of areas where infected vectors were located

• Performance-based possum control contracts with independent monitoring

• The introduction of GPS trap location in the early 2000s

• The introduction of PDA’s for realtime recording and data transfer in 2007

• Efforts by the Southland TBfree committee to gain and maintain buy-in and support from local farmers

This work is funded and managed by the Animal Health Board whose mission is to eradicate bovine TB from New Zealand.  Recently the Board has focused control efforts on the eradication of TB from localised possum populations that are known to be infected.  Monitoring continues at a lower level in TB free locations.

In 1995 approximately one million hectares of Southland were considered to harbour wild animal populations infected with TB that could be passed on to cattle and deer herds. The areas of risk were centred on the Takitimu Mountains, the Hokonui Hills, and south-eastern Southland adjacent to the Catlins forests.

At that time there were 56 infected herds. Today there are only two and the drop is a direct result of the TBfree New Zealand programme that included a combination of vector control (mainly possums), TB testing of livestock, and stock movement controls.

Blackmount sheep & beef farmer Mike O’Brien has been involved with the TB eradication campaign since the 90’s and has been Chairman of the Southland TBfree Committee for the past 10 years. He says that they have learnt from experience that TB eradication is a long-term project:

“It’s not just a matter of getting out there and killing a few possums. In the 70’s the Hokonui area was targeted because it was an obvious hotspot, but although they knocked back both the possum population and the TB infection rates, they made the fatal mistake of not maintaining a control programme for long enough. 20 years on and not only had the possum numbers come back, but TB infected herds had risen to an all time high losing all the gains made ,” says Mike.

“So since the 90’s we have used a variety of methods to reduce possum numbers, including trapping and poisoning. If you concentrate on one method all the time then you will get either trap-shy or poison-shy possums, so you have to change. A combination of methods is essential, especially in difficult and inaccessible terrain. We used an aerial 1080 drop in the Hokonuis following the failure of ground control, and this proved to be the one thing that really knocked the disease down because it achieved such good, low, even control of the possum population.”

TB infected herds surrounding the Hokonuis dropped from 33 to 5 in one year following the operation. Mike says that the number of infected herds subsequently fell to zero for a short time, but then went back to two, indicating that the disease had not been eradicated from the possum population in that location.

Early successes were achieved through good management of trapping, poisoning and monitoring contracts. In the early 2000’s control was enhanced by the introduction of GPS equipment, and later through the use of Personal Data Assistants (PDA’s).

Lyndon Dynes, a senior field supervisor for the AHB in Southland who has been working in pest control since the late 80s, explains. “Originally we used performance-based contracts to reduce possum numbers along with separate monitoring to ensure that contractors were working effectively. It was quite a broad brush approach over a large area and we needed to fine tune it,” he says. “In about 2002 we put bar codes on all the traps and required contractors to record the GPS location of each one. This allowed us to see the coverage being achieved, see where possums were being caught and identify hotspots. It may be a single gully where suddenly you find 40 possums because it may have been missed in the past, or perhaps a crop has caused the possums to congregate.”

PDA’s were originally used just by monitoring contractors, but Southland pioneered their use for recording captures, trap deployments and non-target species captured. This was of great value for surveys where caught animals were sent to a lab for autopsy to determine whether or not they were carrying TB. Now these devices are being used to record and transmit data in real time to AHB databases, and this allows the rapid pinpointing of locations where infected possum populations can be targeted.

Earlier this year the Animal Health Board announced a new strategy that will start focusing on eradicating TB from possums in those populations known to harbour TB. This plan is now being implemented in Southland and includes intensified targeted control by poisoning and trapping which will need to be in place for some time yet. All going well, says Mike O’Brien, the region should end up with all herds being TB free.

“But even after the last infected herd is cleared, farms will still need to be visited by AHB contractors to control or sample wild animals, TB testing restrictions will have to remain in place however we will phase movement control out over time,” says Mike. “I think farmers understand that it could take quite a while to get TB out of the wild population and that we will have to be vigilant and keep testing to ensure that there is no recurrence of infection.”

Both Mike and Lyndon pay tribute to the dedication of contractors who work in the region and to the co-operation of farmers.

Says Mike: “You can have all the rules and regulations you like but unless you have got the backing of local stakeholders, you are not going to succeed. Farmers are very supportive of the Southland TBfree Committee and we act as a link between them and the AHB. Our biggest role is keeping farmers on side with the TB scheme.”

Lyndon is very proud of the region’s achievements. “It’s an ongoing battle and we still have a fair way to go. Success relies on a team effort involving the high quality contractors we have in the southern South Island area plus a very good management team working with farmer groups, and the cooperation from farmers overall is excellent.”