South Waikato, Otorohanga and Waitomo Districts are among a group of regions which have stopped growing or are in decline. Reasons are being sought for the population loss.
Experts say the situation may be past the point of no return in some areas.
World population recently reached seven billion, but globally population growth is projected to end during the second half of this century, and in New Zealand, sometime before that. Already, 15 of New Zealand's 67 territorial authorities have seen their populations either stop growing or go into what will be permanent decline.
Professor Natalie Jackson from Waikato University's National Institute of Demographic and Economic Analysis (NIDEA) has been working with summer research scholarship student Dave Greenslade to examine the triggers for decline.
Once we can explain the triggers, then government and local authorities can plan for the future, says Dave Greenslade. But what councils first have to accept is that many are past the point of no return. While Auckland may keep growing, overall, New Zealand's population will not.