The Ministry for Primary Industries (MPI) has launched an independent review of two of its own investigations.
Newshub revealed the existence of the reports into illegal discarding of fish by some South Island-based fishing vessels in 2012 and early 2013.
The leaked data from MPI states that during Operation Achilles, between 20 percent and 100 percent of some quota fish were being discarded every time the net was pulled up.
A decision was initially made not to prosecute those filmed dumping fish, but that has now been included as part of the review, which will also investigate another Operation named Hippocamp.
Operation Achilles was written by a senior MPI investigator and details what it describes as "serious", widespread offending in the South Island. MPI decided not to release the report publicly.
The operation was part of a trial of CCTV cameras on board the boats, and it found four of the five vessels equipped with the technology "openly discarded substantial quantities of quota fish" without reporting it.
Copies of a preliminary investigation report have now been placed in the public arena, after being leaked.
"I place a high priority on the Ministry having strong credibility with the public when it comes to our role as the regulator of fisheries in New Zealand and our role in holding people to account when illegal activity takes place. Each year, the Ministry prosecutes in excess of 300 cases in the fisheries sector and issues over 3000 infringements," said MPI director-general Martyn Dunne in an emailed statement.
An independent Queen's Counsel will undertake the review.