The net flow of migrants turned negative in March as a jump in departures of Christchurch people amplified a continued trend of dwindling net gains.

Statistics New Zealand reported that departures of permanent and long-term migrants exceeded arrivals by 530 in March on a seasonally adjusted basis.

That is a turnaround from a net gain of 470 in February and of 960 in March last year. It is unusual to record no net gain of population from migration in a month, and this net outflow was the largest for 10 years.

Departures of Christchurch residents more than doubled to 1100 from 500 in March 2010. This counts people leaving the country with the intention of staying away for at least a year.

Even if the 600 increase in Christchurch residents leaving is added back, the net inflow would have been just over 100. It has been declining since October last year. The net gain for the year ended March was 6600.

"Before the earthquake, the trend of New Zealanders relocating to Australia was already in place, given Australia's economic outperformance," ASB economist Jane Turner said.

(Source NZ Herald, Brian Fallow)