Rakiura/Stewart Island Department of Conservation (Doc) acting operations manager Alex Macleod confirmed the last phase of the drop was completed last Wednesday morning.
"It has gone successfully ... we’ve got to get it right because we have sunk a quarter of a million dollars into this job, so hopefully it has gone well."
The department will be engaging a dedicated ranger to continue to work towards regaining a pest-free island.
Rat numbers would be checked over the coming months to determine the effectiveness of the drop.
He said it was important at this stage to "hold the gains", so more investment had been made in establishing more traps and monitoring.
The eradication programme had been managed by the national team who would continue to maintain monitoring on the island.
Path and beach cleanups were next on the project list to finish the job off, he said.
Ulva Island/Te Wharawhara has been named one of the few pest-free open sanctuaries in New Zealand and is home to vulnerable species such as kiwi, weka, saddleback and yellowheads.
Ulva Island, considered to be the jewel of Rakiura National Park, is a 267ha island with an 11km coastline, inside Stewart Island-Rakiura’s Paterson Inlet.
The island was established as a pest-free sanctuary after an intensive rat eradication programme was launched in 1992, and declared rat-free in 1997, but from 2021 numbers had fluctuated again.
The island’s proximity to Rakiura-Stewart Island — less than 1km away — made it more vulnerable to re-invasion.
Murihiku mana whenua have placed a rahui over the fishery covering a 1km offshore radius around Ulva Island, which recommended no fish be consumed from within the banned area until all traces of the toxin were no longer present within key indicator species such as blue cod, trumpeter, pāua, kina, mussels and limpets.
- By Toni McDonald
