The number of immigrants who leave after staying for more than a year has doubled in the past decade.
Migration researcher Professor Richard Bedford told an immigration conference in Auckland yesterday that many more people who came to this country intending to stay for the long term were now leaving
for the long term.
In the year to March 1996, 11,930 migrants had left, intending to stay away for 12 months or more, compared with 22,090 in the year to March 2006.
The figures do not include New Zealand citizens.
Of those migrants who left in the 12 months to March this year, 41 per cent were originally from Asian countries and just over half were from traditional migrant source countries such as Britain.
Professor Bedford thought some migrants weren't settling because of the difficulty of getting other family members into the country.
He said the family quota was not being increased in proportion to the growing numbers of migrants coming in.
Professor Bedford, convener of Waikato University's migration research group, said much of the pressure to bring in family members came from the Asian migrants.
"We have sought people from that part of the world but not made it easy for them to have their families here."
He gave a warning that New Zealand could not assume countries such as China and India were bottomless sources of skilled migrants.
They were increasingly competed for by other countries and some were now wanting to return home as local opportunities increased.
Chinese migrants to Canada were increasingly returning to China, he said.
Professor Bedford said global migration was increasingly mobile.
New Zealand had the highest per capita rate of immigration and emigration in the OECD, as well as the largest numbers of its people living overseas relative to its population size.
Professor Bedford considered the biggest challenge facing New Zealand in the next five years was to stop its workforce being gutted by other countries trying to lure the country's skilled workers.
