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.
He says they're still assessing the data and each area tends to have different characteristics, but clearly these 15 districts have a significant deficit of young adults. Young women in particular are moving away and not coming back, so not only do you lose them, but you don't get the children they may have.
Tied to that, Mr Greenslade says areas in decline usually have more men than women. In the labour market, entry and exit ratios are being affected by the loss of young adults, coupled with the impact of low birth rates over recent decades. As the working population ages and retires, it's becoming harder to replace these people, so in time it becomes harder to find a plumber or a doctor for example.
Professor Jackson says some people still have their heads in the sand about this issue and view continued population growth as a given. But while we have economic cycles, we do not have demographic cycles and that can be difficult for people to accept. We're providing the evidence base for them. This is a new and permanent reality. Overall growth is coming to an end.
Professor Jackson says immigration is no quick fix. Immigrants grow old too, and apart from some small sectors, many immigrants have few children because they come here to work, under the business skills visa category,.
Districts that have stopped growing or declined, 2006-2010 include Chatham Islands, Gore, Kawerau, Opotiki, Otorohanga, Rangitikei, Ruapehu, South Taranaki, South Waikato, Tararua, Wairoa, Waitaki, Waitomo, Wanganui and Whakatane.