"Some of the areas where commercial fishing is conducted are beyond the reach of MPI patrol vessels, but are easily within the range of the Navy," Rudsdale said.
"When a big grey ship turns up the fishers can get a bit of a surprise."
Inspecting vessels at sea provided MPI with an opportunity to ensure fishers are complying with regulations by checking their catch, equipment and fishing methods, and officers needed to be able to get onboard fishing vessels to see if their reporting matches what was being caught, as well as checking that commercial fishing equipment and methods complied with the regulations.
"We also check that birds and other non-fish species are not being caught or are returned safely," he added.
Measures were in place to ensure the sustainability of fisheries, including accurate and truthful catch reporting for commercial fishers.
Since December last year commercial fishers had been required to use geospatial position reporting and electronic reporting systems, to inform Fisheries know in real time where vessels were working and what they were catching.
"Those who don't respect the rules will be appropriately dealt with under the law. The taonga we are protecting is important to all New Zealanders," Rudsdale said.
Any suspicious fishing activity should be reported to the MPI on 0800 4 POACHER (0800 476-224).