A sharp rise in ACC claims for injuries caused by "fighting" pushed the taxpayers' bill for assault injuries, including smashed teeth, broken wrists and concussion, to almost $7 million last year.
There were 1188 more Accident Compensation Corporation assault claims lodged last year than in 2010.
Among the injuries sustained from street brawls and domestic abuse were 906 cases of broken or damaged teeth, 669 concussions or brain injuries and 658 fractured hands or wrists.
And those results are limited to victims who stipulated "fighting" as the cause of their injuries. The total cost to the taxpayer for those injuries will continue to rise as they receive further treatment.
YouTube videos of street brawls and playground punch-ups, often recorded on mobile phones, hint at the extent of New Zealand's problem with fighting.
"Youth violence has been relatively stable over the past 20 years, but what we have noticed is an increase in the last few years of more serious youth violence," said University of Auckland clinical psychologist Ian Lambie.
He said many of those who turned to violence came from dysfunctional families: "They're not all bad or evil. There is another side to them. Largely, it's got to do with the way people are parented. We have to look at the parenting skills and way kids are treated. Some of these kids have high rates of abuse and neglect."
Lambie said the problem could be curbed by putting funding into proven anti-violence programmes.
"You can never turn the tap off but you can certainly turn the flow down significantly. The way you do it is providing early prevention – potentially before the kids are born. If the mother is a high risk parent, give them support."
Research also shows a link between binge-drinking and a culture of violence.
Alcohol Healthwatch director Rebecca Williams said alcohol was New Zealand's biggest social issue.
"When that type of [binge] drinking is dominant within the population you will see violence and crime," she said.
"The messaging in alcohol advertising doesn't help the issue. It sells this macho thing – like alcohol is some sort of joke.
"But so often these incidents don't end up fun. They end up with people emotionally or physically hurt."
About a third of all domestic violence can be linked to alcohol in New Zealand. This causes ongoing mental health issues.
"Children grow up in those households and turn to drugs and alcohol because they're unhappy in their homes."
Victims of domestic abuse and street fighting were both included in the ACC statistics. The majority of these ACC claims reported "assault" or "fighting" as the main cause of injury. Auckland had the highest number of assault victims, with 5139. Canterbury had the second most assault claims, with 1678 injuries last year.
Police figures for reported assaults in 2011 were not available yet, but officers attended 44,465 assaults in 2010.
The total number of assaults police attended has been steadily climbing over the past five years, although assaults did drop marginally between 2009 and 2010.
Most common assault injuries in 2011.
Cuts to the head and face 2175
Facial bruising 1808
Damaged teeth 906
Concussion and brain injury 669
Hand or wrist fracture 658
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