The Bennett's wallaby used to be confined to South Canterbury, an area from the Rangitata River south to the Waitaki River and lakes, inland to the Tekapo River and back to the headwaters of the Rangitata.
Before 2008, there were isolated reports of individual dead or alive wallabies south of that area in North Otago.
In 2008, signs were found on the south bank of Lakes Waitaki and Aviemore on five properties covering about 80,000ha, centred on the Aviemore Dam and gullies.
ECan biosecurity team leader in Timaru, Brent Glentworth yesterday said that since then, Environment Canterbury (ECan) has been conducting eradication programmes in the new area, with contractors or farmers shooting 38 wallabies, including eight this year.
The latest move, after discussions between Meridian Energy Ltd and ECan, is the construction of a 1.5km-long wallaby-proof fence by the owners of the Aviemore Dam from Fisherman's Bend (at the top of Lake Waitaki) to the Deep Creek lagoon (west of the dam).
Wallaby numbers had increased, putting pressure on the containment area and pushing them south, he said.
It was hoped the fence would prevent wallabies crossing the Aviemore Dam and boosting numbers to the south.
Mr Glentworth said some of the country was very rugged to cover and contractors with dogs were needed to flush out the pests. A helicopter had been used for searching and poison had been trialled.
Mr Glentworth said ''a considerable amount of money'' had been set aside for what would be a continuing programme until there were no signs of wallaby.
''Our aim is to eradicate them [south of the Waitaki River and lakes],'' he said.
Some individual wallabies had been shot outside the containment area, including in the Lindis Pass.
It was suspected these had either been pets that had escaped or had been released, both being illegal.
Some hunters took a joey from the pouch of a shot wallaby and kept it as a pet. It was illegal to take wallabies outside the containment area and they could only be kept under licence.
