It protects more than 2400ha of coastline and protects marine life from threats that may harm its existence.
"When people intentionally disturb that and take marine life from this area, they are destroying this very special habitat," Plumstead said.
DoC's East Coast district manager John Lucas said the actions were disappointing.
"This type of offending impacts on educational opportunities and affects the ongoing restoration of the marine environment.
"We will continue to work with MPI to closely monitor activity around the reserve to ensure those who act illegally will wear the consequences.
"We take a zero tolerance approach to all offending," he said.
As well as facing court, the alleged poachers have had a number of vehicles seized.
MPI and DOC ask that members of the public report suspicious behavior and illegal activity at marine reserves around the country.
Lucas said to alert any suspicious activity, contact MPI on 0800 476 224 or DoC on 0800 362 468.