The third day of search efforts for a Department of Conservation worker missing on remote Raoul Island is under way as hopes dwindle of finding him alive.
The volunteer went missing from Fishing Rock on the island in the Kermadecs about 6am on Monday.
Ground and air searches have failed to find the man, whose name has not yet been released, and the Taupo rescue helicopter has been called in to help.
Doc spokesman Tim Brandenburg told Radio New Zealand that yesterday's search efforts were called off at about 8pm as night fell.
"This morning, the helicopter will be in the air again. The Rescue Co-ordination Centre tells us that it's better they fly later in the morning because the light is better. But we expect them to be doing another circuit over the search area this morning, and our staff on the island will support the helicopter crew as needed.''
The man's vehicle and measuring equipment had been found at Fishing Rock where he was thought to have been taking water temperature readings for a weather station Doc operates for the MetService.
"We're reasonably sure of the scenario of him being washed off the rock is probably what happened but of course we can't conclude that at this stage. But unfortunately last night at the end of the search, we had found no sign.''
He said the area, which is said to be surrounded by cliffs, was not particularly hazardous and was the boat launching and retrieval area.
"There are hazards with working along the shoreline wherever you are, you have to be careful of the conditions.''
He said Doc would not release the man's name at his family's request.
Doc spokeswoman Liz Maire yesterday said there was a slim chance of the man being recovered alive: "I think hope is dwindling.''
The man had been on Raoul Island, about 1000km northeast of Auckland and renowned for volcanic eruptions and almost daily earthquakes, since October on a six-month stint.
He was one of four volunteers helping three DoC staff who monitor seismic and volcanic activity and conduct conservation work to protect the more than 100 plants native to the Kermadecs.
A review of the volunteer programme would follow the search efforts, Mr Brandenburg told Radio New Zealand.
"As part of the investigation all the aspects of the programme there will be reviewed. If we have learnings from the review that would help us to make our staff safer, we will certainly be implementing those.''
Doc was not reviewing having volunteers on the island: "it's a very important part of the programme, we get a lot of interest in it.''
He said there were "good'' procedures around the programme.
Doc worker Mark Kearney, 33, disappeared during a volcanic explosion on the island in 2006. He is believed to have died when a crater lake erupted as he was checking its water temperature. His five colleagues were rescued.
