The number of cannabis convictions in Tauranga District Court has more than halved over the past five years, according to official figures.
Ministry of Justice records show the number of cannabis-related convictions dropped from 449 five years ago to 202 in the last financial year. The convictions included dealing, trafficking, importing, exporting, manufacturing, cultivating, possessing, using and other illicit drug offences.
Possession and use convictions had the biggest decrease from 193 convictions in 2010 to 68 last year. Manufacturing and cultivating convictions all dropped significantly - down 42 over the five-year period, while dealing and trafficking convictions fell slightly.
A national police spokesperson said the drop in cannabis-related offences correlated to a reduction in over-all recorded crime.
It was too early to assess what effect the ban on synthetic highs had had, the spokesperson said.
Tauranga acting Detective Senior Sergeant Alan Kingsbury said Western Bay of Plenty's climate provided favourable conditions for criminals involved in cannabis cultivation.
"The annual national cannabis operation and regular local police operations have proved very successful in disrupting and dismantling these activities," he said.
Recreational use was also an issue in Tauranga, as it was in any town or city in New Zealand, he said. "Drug use and alcohol are frequent factors in much of the crime that we deal with day to day.
"Many who abuse substances are unable to hold down employment and steal to feed the habit. In the majority of cases involving physical violence, drugs or alcohol is a factor."
The public played a vital part in removing illicit drugs from the community, he said.
"It is a problem that our communities need to own, and a lot of our successes are the result of communities taking a stand against drugs by providing us with valuable information."
Nationally, district courts convicted more than 25,000 people for marijuana-related offences over the past five financial years.
The total number of convictions decreased each year from 7329 in 2010 to 3480 last financial year.
New Zealand Drug Foundation executive director Ross Bell believed greater use of pre-charge warnings by police was the main reason for the decline.
"The simple explanation is police are processing people differently," he said. "I think there's a small decrease in the number of people using cannabis but not big enough to account for those numbers."
Mr Bell expected greater education around the harm caused by substances had turned some people off the drug.
"We've seen in some of the surveys that have been conducted in secondary schools that a whole lot of risk-taking behaviours - cannabis use, tobacco use, alcohol consumption - are coming down, so that seems to be a cultural shift.
"People are getting a whole lot of messages around tobacco - it's expensive, there's age restrictions, there's horrible pictures.
"Young people seem to be picking up an associated message that any kind of smoking isn't healthy."