Assaults among female prisoners have almost doubled in the past year, despite the prison population dropping.
Corrections say an increasing number of gang associates in jails may, in part, be to blame for the escalating assaults.
Former prisoners fear the number of reported attacks are only the tip of the iceberg, in an environment some say is "traumatic and stressful".
Corrections data released to the Herald under the Official Information Act shows reported assaults were 22 per 100 prisoners in the year 2018/19, up from 12 in the previous year.
Patricia Walsh, who has served time in New Zealand prisons, witnessed frequent attacks throughout her time in jail, and said at nights people would often call out telling others to hang themselves.
"There's no escaping it, out here it might happen in a certain place, but in there you're living it. If someone decides they're going to hit you the only way out is to go into segregation or you go and tell a guard and then you're a nark which has other consequences."
One attack burned into Walsh's mind was watching as one woman tipped scalding water onto the skin of another.
The former prisoner said straight after dinner, when some of the staff left for the night, people would torment other prisoners.
In the last recording year, the prison population dropped to 762 from 897 in the previous year. During that time the total number of assaults grew from 94 to 161.
"We're already traumatised because we are women and you're already removed from you whanau, your children."
Walsh said those things build up in prison, so some people take out any additional stress by bullying.
Corrections Deputy National Commissioner Andy Milne said violence in prisons was not solely a consequence of how prisons were managed or operating.
He said there was extensive evidence both here and in other countries, demonstrating that gang-affiliated prisoners had higher levels of involvement in prison violence.
Human rights group Amnesty International New Zealand told the Herald the increase clearly highlights the need for more transparency around what is happening in the country's prisons.
Executive director Meg de Ronde said it was concerning to see the increase across all prisons, but in particular Auckland Region Women's Corrections Facility, which saw assaults grow from 56 to 104.
Under the classification used by the Department of Correction, these assaults are defined as non-serious and include those that resulted in overnight hospitalisation, bleeding nose, X-rays, cuts requiring minimal stitches, gouging and bites.
Serious assaults, which are defined as bodily harm requiring ongoing medical intervention; or sexual assaults where police charges are laid, are very rare. Only three have been reported in the last five years.
De Rond said if Corrections were suggesting there could be a causative link between rising assaults and women with gang affiliations, it was a tenuous and problematic assertion.
"It seems to us that that's just a deflection of responsibility, and they actually have a responsibility to ensure that the rights of those prisoners to be safe are upheld."
The number of wāhine in prisons with gang affiliations rose from 84 in 2015/16 to 128 in the latest recorded year.
Corrections said it's capability to detect and establish the gang connections had developed in the past 10 years, which had resulted in the increase in the number of prisoners with gang connections.
University of Auckland Indigenous Studies professor Dr Tracey McIntosh said it would be difficult to attribute the gang association to the increase in violence over these particular years.
"The gang association within prisons, while it has increased, has been present there for quite some time."
She said the characteristics of women in prisons were very homogeneous; early experience of violence, exclusion from the compulsory education system from a young age and living in socio-economic deprivation.
"It's important to understand that amongst women in prisons we have extremely high victimisation rates, far higher than in the general population. And again, it means that violence is something that is known and perhaps understood."
McIntosh said there was far greater anxiety and stress in women's prisons than men's, with many women dealing with fears over the welfare of their children.
"The women who have children, are much more likely to be involved with the day-to-day care of their children, so their arrest, for example, can disrupt the whānau line."
Concerns were especially high regarding their children going into state care, as McIntosh said many of the women had been through it and did not want that for their children.
She said there were a range of factors that could have impacted the level of violence, including double bunking, quickly turning populations, boredom and volatility in the prison environment.
Inside "the wire" she said some may feel like reporting violence is not be in their best interests.
"The fact that there would be under-reporting [of assaults] in a prison environment is extremely likely to be the case. Now If you think about family violence, sexual violence, we know that there is serious under-reporting."
Corrections said every assault- whatever the level of injury- will not be tolerated and it's
constantly working to provide the safest possible environment for both staff and prisoners.
"This includes encouraging prisoners and staff to report all assaults regardless of
whether they result in injury."
The union was also concerned with the growing levels of violence inside New Zealand's prisons.
Assaults by incarcerated women against staff increased from 6.3 per 100 prisoners (35) in the 2014/15 period, to 10.1 per 100 prisoners (73) in 2018/19.
Corrections Association union president Alan Whitley said members felt many charges that should have gone to an open court weren't being prosecuted.
"They're [prisoners] not being held to account to a level that we're happy with."
He said sometimes when charges do go to court, judges would give a concurrent sentence and it just became a "print on their record" and they spent no extra time in prison.
"About 18 months to two years ago we started to soften the approach to dealing with prisoners, we started calling them people in our care and other nice names to call prisoners, and that's when we noticed that prisoners weren't being held to account for their actions."
He said Corrections officers don't go to work every day to get assaulted, but they keep heading in because "someone's got to do it".
Milne said no rules around prisoner management had been softened and prisoners found guilty of an assault will be held to account.
He said there had been no direction to refer to prisoners as "people in our care", but the shift away from the consistent use of terms like prisoner and offender was in line with a strategy announced in August 2019.
Accounts from incarcerated wāhine also suggest the data of reported violence is only a fraction of what's actually happening.
Former prisoner and restorative justice worker, Jackie Katounas, has experience from both sides of the bars.
During her time in jail, she said when assaults were planned, they would usually occur outside the view of prison guards or away from their direct gaze.
"You're always on high alert, you're always watching your back and have eyes in the back of your head. You're just careful, you tread carefully, and it can be quite draining emotionally you know?"
Katounas agreed that incarcerated women were also on edge because of uncertainty surrounding childcare.
"For women, it's particularly more stressful."
Corrections said it has a five-year gang strategy to help contain the negative influence of gang members in the custodial environment and was taking steps to discourage prisoners from gang membership.
Milne said they review every use of force, including CCTV and on-body camera footage and have multiple avenues for prisoners to report concerns.
The Department said it had implemented a range of initiatives in the last several years to reduce reoffending.
This includes expanding it's existing Kowhiritanga rehabilitation programme - an evidence-based model that targets the attitudes and behaviours that contribute to women's offending.
It opened Te Mana Wahine unit at Arohata Prison - a specific kaupapa Māori rehabilitation and reintegration programme designed for Māori, but available to all women.