News Hub reports it's the third time the crew aboard the HMNZS Hawea have caught offshore vessels breaking the law when it comes to proper disposal of waste.
The area is a multimillion-dollar tuna fishery - a precious resource that's often abused.
On board a Chinese long-liner, around 15km from land, the hold contains a sizeable catch of Albacore and Yellowfin Tuna, but it appears this haul matches the captain's books.
The vessel has a total of around 80 tonnes of fish on board, and the crew's documentation appears to all be in order.
But they've been at sea for more than a month and there's a question over where all the crew's rubbish is.
"So they've been out at sea for 30 days and any rubbish that they do have they've just been ditching overboard on a daily basis," Sub Lieutenant Julian Grimmett, Boarding Officer on the HMNZS Hawea, tells Newshub.
Dumping rubbish can attract a fine of up to $500,000 and it could impact their ability to get a future licence.
"That's the third offshore vessel that we've come across in the Fijian EEZ out of 20 boardings that's been disposing its rubbish at sea," Commander Officer Lieutenant Dave Luhrs says.
There's no doubt the Kiwis are having an impact, with the 55-metre-long Hawea now a regular sight on the horizon in this part of the South Pacific.