Rotorua defence lawyer Rob Vigor-Brown agreed the figures were down.
"I believe that is because police are issuing pre-charge warning systems."
Mr Vigor-Brown said he believed the pre-charge warnings and infringement notices were ways to deal with "Huckleberry Finn-type" behaviour.
"It's to the benefit of both the offender and the community that people don't have the albatross of a conviction hanging around their necks."
The number of new and ongoing defended civil cases in the Rotorua District Court was also down year-on-year, while the number of cases the Youth Court heard was up.
The Rotorua Family Court had handled fewer new cases but more ongoing cases than it had in the previous year.
Nationally, district courts had fewer new, ongoing and disposed criminal and civil cases than in the previous year.
Fewer new criminal cases nationwide could be attributed to the police's greater use of pre-charge warnings that aimed to divert lower end offences away from prosecution and court proceedings, the Courts New Zealand report said.
Statistics New Zealand data showed conviction rates were the lowest in the 34 years for which statistics had been available, in the year ending June 30.
The police, Ministry of Justice and Department of Corrections were working together and with other agencies to reduce crime and offending, acting general manager of the justice sector Dean Rutherford said.
Crime rates in New Zealand, as was the case in many Western nations, had been dropping for many years, he said.