The net outflow of migrants continued in January, pushing the annual population loss from migration to 3100, its highest for more than 10 years.

Permanent and long-term departures exceeded arrivals by 650 in January, on a seasonally adjusted basis. That is a level exceeded only once (in September last year) since February 2001. The net flow has been negative for 10 of the past 12 months.

The loss over the past year compares with an average gain of 16,300 over the preceding 10 years.

In the year ended January there was a net loss of 38,100 people to Australia, the largest yet recorded, reflecting 51,900 departures offset by 13,800 arrivals, Statistics New Zealand said. In both directions most were New Zealand citizens. But economists noted that on a seasonally adjusted basis departures to Australia have been declining in recent months.


They were now at their lowest level since February last year, Infometrics economist Matt Nolan said, and had declined 13 per cent from their peak last September.

"With the Australian labour market softening, we expect further declines in permanent departures to Australia."

Goldman Sachs economist Philip Borkin said that the larger overall net outflow of migrants over the past few months had been driven by a drop in arrivals, which have fallen to their lowest level since 2005, while departures remained largely unchanged. The Auckland region was the only one to buck the trend. It recorded a net gain of international migrants of 5600 in the year to January, while Canterbury suffered a net loss of 3700.

Borkin said slowing population growth would weigh on household consumption and domestic demand more broadly this year.

"Our forecasts assume population growth slows to around 0.7 per cent over 2012. This is from estimated 0.8 per cent growth over 2011 and 1.2 per cent growth over 2010."

Economists expect the trend to turn around as the Australian labour market softens and the rebuilding of Christchurch gets under way in earnest.

"As the New Zealand labour market gradually strengthens, we expect permanent arrivals to pick up and departures to ease from their current elevated level," Nolan said.

"Even so, more people are likely to leave our shores than move here during the first half of the year and, as a result, we do not expect annual net migration to return to positive territory until the start of 2013."