Rising gang tensions could be to blame for a sharp rise in the number of improvised knives seized from prisoners at the Otago Corrections Facility.
Figures released to the Otago Daily Times under the Official Information Act show the numbers of improvised cutting and stabbing weapons — known as "shanks" — seized has increased each financial year since 2017.
In the 2017 financial year, six shanks were seized, but that rose to 23 last year.
Across all five years, a total of 69 improvised knives were found, with the next highest categories of weapons being categorised as "other" (14) and knives (8).
Otago Corrections Facility prison director Dave Miller said the prison population had dropped from a high of 10,820 in March 2018 to about 7900, but there was now a higher concentration of violent prisoners.
Over 80% of the prison population had convictions for violence in their offending histories and 35% were gang affiliated — a known predictor of violence.
The number of gang-affiliated inmates had more than doubled in the last 10 years, Mr Miller said..
"Just as there has been increased gang tension in the community, this has likely influenced the behaviours of gang members in prison.
"We have also seen heightened gang rivalries within the prison environment," Mr Miller said.
The increase in the numbers of improvised weapons found also indicated staff were vigilant and thorough in their work, he said.
The prison placed significant emphasis on detection of contraband in prisons, and improved intelligence and daily searches of units, cells and prisoners meant any weapons were found quickly.
A recent focus on enforcing cell standards had meant an increase in cell searches and therefore an increase in contraband being found.
"We reinforce with staff the need to report all contraband finds, especially those involving items that could be used as weapons," he said.
The data also shows that there was one instance where either ammunition or explosives were found in the 2020 year.
Over all five years, there were two bludgeoning implements found, and one example each of recreational equipment and a tool being seized as weapons.
