New Zealand's fishing industry has again come under fire after Greenpeace released a leaked Government report that showed thousands of tonnes of fish dumped and unreported. (File photo)

A leaked Government report has shown thousands of tonnes of fish dumped and unreported, renewing calls for an independent inquiry into New Zealand's fisheries management.

The Ministry for Primary Industries (MPI) report, released by Greenpeace on Tuesday, showed up to 2677 tonnes of southern blue whiting was dumped by fishing companies in 2012 – up to 6 per cent of the total allowable commercial catch that year.

MPI later on Tuesday released the full report, as well as a 2013 report. It said the reports prompted more accurate reporting by the industry and changes by MPI to ensure the way the fish was processed was more transparent, so did not reflect the current situation.

The 2012 report said the 2677-tonne figure included only waste from non-compliant head cuts, meaning too much of the fish meat was wasted when removing the head, and did not include other potential means of wastage unobtained due to insufficient data.

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"Therefore, estimates of unreported greenweight [the total weight prior to processing the fish] are considered conservative for this season," the report read.

Greenpeace executive director Russel Norman said the report was inconsistent with what MPI claimed about fishing industry practices.

"We were shocked by the report into the hoki fishery we received last week, which revealed thousands and thousands of tonnes of hoki had been made to disappear," he said.

"Now, we can see that the same thing has happened with our southern blue whiting fishery,"

Norman said the under-reporting meant "millions of dollars in savings for fishing companies [that] didn't need to purchase quota for the disappeared fish".

"The result is that no-one really knows exactly how much fish has been taken."

MAARTEN HOLL/STUFF Greenpeace executive director Russel Norman has renewed calls for an independent inquiry into New Zealand's fisheries management.

Greenpeace criticised MPI for releasing just 11 pages of the 53-page report under the Official Information Act, as it had done with the report into similar activity in the hoki fishery.

Norman said MPI "simply cannot be trusted to tell the truth or regulate the industry".

"MPI is captured by the fishing industry. We need an independent public inquiry into the Fisheries Management System and its regulator," he said.

"Right now, MPI and the seafood industry are trying to prevent this independent inquiry and are instead pushing for an internal MPI review, but this further leaked report shows once again why that must not happen."

MPI rejected Norman's claim. A spokeswoman said as well as work prompted by the reports, MPI was introducing measures such as digital monitoring that the fishing industry was not altogether comfortable with.

The MPI report mentions the southern blue whiting fishery was New Zealand's third fishery to be given Marine Stewardship Council (MSC) certification, essentially awarding it an "eco-label" in 2012.

In a statement, Forest & Bird said it appeared the fishery had "kept its 'sustainable' certification by hiding widespread fish-dumping and misleading customers".

"Neither MPI nor the fishing industry appears to have shared this information with eco-certification body of the [MSC]."

JARRED WILLIAMSON/STUFF Fisheries Minister Stuart Nash has previously said scrapping the roll-out of fishing boat cameras is an option, but the leaked reports have reinforced Forest & Bird's belief they "can't come soon enough".

An appendix to the MPI report noted "the already significant value of this fishery has been further enhanced by quota owners investing in the MSC certification process".

Forest & Bird chief executive Kevin Hague said the statement revealed a "conflict of interest between the industry and the MSC assessments, and the strong incentive on the fishing industry to cover up illegal activity".

In February, Fisheries Minister Stuart Nash said cancelling the roll-out of cameras on fishing vessels, introduced by the previous National government, was an option.

Hague said the southern blue whiting and hoki revelations showed "cameras on boats can't come soon enough".

"Sadly, the fishing industry's worst enemy is themselves. The onus is now on them to prove that they are committed to transparency and truth-telling."

MPI said the report aimed to identify the extent to which catch reporting may have been inaccurate and the reasons for those inaccuracies.

Compliance investigations manager Gary Orr said it prompted the industry to change its processing procedures, resulting in more accurate reporting.

"There have been a number of important changes made in deep water fisheries since this exercise with the most notable being the requirement for foreign-owned vessels to be New Zealand flagged. This resulted in a number of foreign charter vessels leaving New Zealand," he said.

"It is also now a requirement for all foreign owned vessels to have an MPI observer on board.

"These changes and improvements demonstrate the value of all of our risk assessments: they ensure that some behaviours are changed and that fisheries management practices are as transparent as possible."

Orr said MPI was now proactively releasing all of its historical risk assessment reports on its website.

"We have published summaries of these reports in the past in the public interest. However, as some of these historical reports have been leaked to the news media and have been published, we are now taking the step of releasing them all."

* An earlier version of this story did not include any comment from the Ministry for Primary Industries. Stuff apologises for not including it at the original time of publication.