KEY POINTS:
At least half of electorate seat boundaries will be changed for the 2008 election as a result of shifts in population.
But only one new general seat will added, probably in Auckland, and the number of Maori seats will remain at seven.
Statistics New Zealand oversees a review of the number of seats based on a statutory formula using the last Census and the Maori Option - which gives Maori the chance to change registration between the Maori roll and the general roll.
The Representation Commission will oversee where the boundary lines will be drawn.
It will meet in March and its preliminary redrawn boundaries are expected to be ready in May.
But since the MMP voting system replaced first-past-the-post in 1996, the importance of boundary changes has greatly diminished, because the overall percentage of party votes cast now determines the make-up of Parliament, not who wins and loses electorate seats.
Census 2006 general manager Nancy McBeth said yesterday that at least 50 per cent of the 70 electorates for the 2008 election will need to be changed by the Representation Commission to ensure they are within the tolerance of plus or minus 5 per cent.
Boundary changes will be forced not just by the fact that another general seat will be added to the North Island, but because many electorates are now well outside the tolerance levels.
For example, Clevedon and East Manukau exceed the quota by 19 per cent, followed by Auckland Central and Hamilton East, which exceed it by 15 per cent.
Similarly, population shifts mean that some electorates are now well below the quota: Clutha-Southland by 12 per cent, and Invercargill, Taupo and Wairarapa by 10 per cent.
The new population quotas around which the boundary changes will have to be made are:* 57,243 people per North Island general seat (up by 2947).* 57,562 people per South Island general seat (up by 3254).* 59,583 people per Maori seat (up by 6484).
The Maori Party was disappointed the increase in the number of people on the Maori roll and in the population has not translated into a new Maori electoral district.
The party had campaigned to get more people signed up to on Maori roll in the hope of creating an eighth Maori seat and nearly 15,000 additional people did so.
The Maori Party won four of the seven Maori seats in the September 2005 election.
"Given all this growth it is of course disappointing that the figures didn't translate into an eighth electorate seat," Maori Party co-leader Pita Sharples said.
He said there was a serious problem with youth not voting - about half of those eligible to vote who were not enrolled were aged under 25.
Co-leader Tariana Turia said Maori were concerned about the effect of immigrants on political power and electoral change.
"Since the last option was carried out in 2001, 250,000 immigrants have come here from other countries," Mrs Turia said.
"We have had many queries from tangata whenua about how Government's immigration policy is impacting on their political power."
- additional reporting: NZPA
