A researcher says the Government needs to address a rising tide of violence and aggression among teenage girls.
The country's first study into "girl fighting" by social anthropologist Donna Swift warns of a flourishing culture of put-downs and intimidation that is going to lead to more violence.
The study was commissioned by Stopping Violence Services based in Nelson.
Dr Swift spent two years in the Tasman district interviewing 104 teenage girls with a history of violence and surveyed 3424 students in years 9 and 10.
The researcher found anti-social behaviour and fighting between girls is becoming normal for many teenagers at secondary school.
Dr Swift says some girls are fighting as a form of entertainment for boys and to build their reputation among peers. Girls are engaging in cyber-bullying more than boys and are more verbally abusive.
Police statistics show the number of females aged 10 to 20 apprehended for assault has increased 83% in the past decade to more than 3000 last year.
In 2000, there were 1674 girls apprehended, compared with 3063 in 2010.
The rate for males in the same age group rose 43% across the same period, from 5210 apprehensions in 2000 to 7437 in 2010.