The number of incidents had been falling in recent months.
Prisons were "dynamic" places and Whanganui had its unique challenges, he said.
At Whanganui Prison 41 per cent of inmates were either in or associated with a gang compared with 36 per cent nationally, while 47 per cent were violent offenders.
"I just want to provide context," Beales said. "The people we are looking after in that prison, they're quite problematic. They have got complex issues ... sometimes they can be dangerous.
"It shouldn't be forgotten that many prisoners are already [connected with gangs] before they come to us.
"Prisons are very dynamic environments where there's lots of things happening through the day."
Beales said the prison was now implementing a gang engagement and management and anti-bullying strategy which would tackle some of the recruitment and criminal activity issues within the prison.
"That's a long-term strategy," he said.
"We're satisfied that they are making good progress ... but it's always going to be a challenging situation."
Meanwhile, Beales said there hadn't been any issues in Whanganui Prison as a "direct result" of Mongrel Mob member Kevin Ratana's shooting last month.
"We always keep a close eye on what's happening in the community," Beales said.
"When something happens in the community that could spill over into the prison … it's something that we have to be cognisant of."
Beales was pleased the Boshier report highlighted positive interactions between staff and prisoners.
"This is an acknowledgement of the professionalism of our frontline staff who have, at times, a demanding job to do.
"The report noted a number of positive practices at Whanganui Prison during the unannounced visit by inspectors in early 2018."
These practices included the addition of mental health clinicians on staff, high standards with regard to Use of Force records, and the work of the Case Management team.
Other action taken by the prison included the introduction of new constructive activities for prisoners such as weaving, yoga and correspondence education and the addition of 150 new mattresses and scheduling additional dental appointments.
"We are committed to transforming the way we manage these prisoners and do everything we can to improve people's overall wellbeing so they can engage in activities aimed at helping them stop offending."
