Rāhui placed over fishing Ulva Island’s waters during pest eradication operation

A rāhui on fishing has been implemented on Ulva Island, Te Wharawhara, near Raikura, Stewart Island, as a predator control operation takes place.

The Department of Conservation (DOC) is using the aerial delivery of brodifacoum toxin to eradicate Norway Rats from Ulva Island, 780m away from Stewart Island, at its closest point, means the island was always vulnerable to reinvasion.

The first of two applications of brodifacoum, a highly lethal poison often used for rodenticide, took place yesterday.

The rāhui sets a temporary prohibition on fishing until all traces of the toxin are no longer present within key indicator species such as blue cod, trumpeter, pāua, kina, mussels, and limpets.

Awarua Rūnaka mātaitai advisor Gail Thompson said fishers should avoid the area.

“We are supportive of the mahi to protect Te Wharawhara (Ulva Island) and our taonga manu, but this rāhui recognises that land activities have an impact on our fishery. We’re imploring the community to not fish or eat kaimoana collected from within 1km of Te Wharawhara for their safety until the rāhui is lifted.”

A second application of bait will take place two weeks after the first application, weather dependent.

Ulva Island was first declared pest free in 1996, with Prince Harry in 2015 describing it a “conservation jewel”.

The spikes in rats on Ulva Island pose a significant threat to native bird species such as the tieke (South Island Saddleback), mohua (yellowhead), titipounamu (rifleman) and South Island kākā.

In June 2022, Estelle Leask, who is a director on the board of Predator Free 2050 and a trustee of the Predator Free Rakiura trust, said Norway Rats, the species found of Ulva Island are good swimmers and quick breeders as their gestational period was only three weeks.

According to DOC, rats have re-invaded Ulva Island more than 20 times since 1997, with most incursions successfully thwarted.