An expert says low immigration numbers have contributed to a population decline in most regions.

StatsNZ figures show populations declined in Auckland, Wellington, Nelson, West Coast, and Southland in the year to June.

Internal migration, people moving around the country, is the main driver of population change in 12 of the 16 regions.

Massey University sociology professor, Paul Spoonley says more people are beginning to leave New Zealand, rather than arrive.

He says if you look back at our population, the number of births have declined and we've increasingly relied on migrants.

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