Invasion of mice on 'predator-free' island

 on predator-free Marlborough Sounds islands.

Senior ranger Phil Clerke, of Picton, said DOC biosecurity experts from Northland and Canterbury had checked protocols for keeping animal and plant pests off island sanctuaries in the Sounds.

Recommendations included appointing a staff member dedicated to making sure people going onto the islands followed correct procedures and constructing purpose-built quarantine sheds.

Biosecurity standards had been improved and refined in the last four years, Mr Clerke said.

"But people need to be kept aware of risks all the time. It is possible for someone who has been working on the islands for decades when there have been no incursions to overlook the obvious."

DOC boats regularly used the jetty at Maud Island, in Pelorus Sound, as well as water taxis, the mail boat and Pelorus Tours, which takes summer visitors to the island, Mr Clerke said.

Staff also occasionally discovered people on the island who were not entitled to be there.

Existing procedures included keeping boats clean and tidy, Mr Clerke said.

Glue boards were installed to trap any unwanted insects or rodents and rodent baits were laid regularly.

Before people stepped on the island they checked their pockets and packs in basic quarantine rooms.

Boots and shoes, muddy clothing and tools were scrubbed with disinfectant to kill chytrid fungi which could kill Maud Island frogs.

Mr Clerke said DOC still had no idea how the mice arrived at Maud.

They were not known to swim that far but it would take only one floating across on a log to start a plague.

Before putting out poison for the mice at Maud Island next winter DOC would probably remove all takahe and kakapo.

DOC permission was also required to land at Stephens Island, The Trios and the Chetwodes in the Marlborough Sounds which were also predator-free, Mr Clerke said.

Blumine and Motuara Islands in Queen Charlotte Sound also harboured rare birds and was predator-free but anyone could land there, he said.

Signs asked that people take care not to introduce any pests and diseases.

The Marlborough Express