Official documents show fishing companies, including Talleys, threatened legal action against the government over proposed seabed protection in the South Pacific.

Photo: 123RF

Forest & Bird obtained the letters sent to Fisheries Minister Stuart Nash and New Zealand First Ministers Winston Peters and Shane Jones through the Official Information Act.

The 2017 and 2018 letters from the High Seas Group, which represents fishing companies that operate vessels outside of New Zealand's economic zone, opposed what were then-proposed conservation rules.

The rules to reduce the impact of bottom trawling were agreed to earlier this year and are implemented by the South Pacific Regional Fisheries Management Organisation, an inter-governmental agency that manages the region's high seas.

The letters wanted the ministers to remove one of the conservation rules and threatened legal action against the government - the move-on rule, which requires trawlers to stop fishing in an area if they pull up too many corals, sponges and other long-lived ocean life.

Photo: 123RF

Forest & Bird said ancient deep-sea coral is dying while fishing companies rake the ocean floor to catch fish found hundreds of metres underwater.

A spokesperson for the conservation group, Geoff Keey, said the letters showed the High Seas Group's persistent effort to prevent minor marine protections in the South Pacific over bottom trawling.

"New Zealanders really really care about their seas, about the oceans, and we care about our place in the Pacific and as a responsible country in the Pacific," Mr Keey said.

"What these letters show is that the industry was not taking care of the ocean - was doing the opposite - and was certainly encouraging the government to be anything other than a responsible player in the South Pacific."

Quotas are in place for fishing in New Zealand's offshore waters, where orange roughy can live for up to 130 years, and are caught using bottom trawling, a method that can damage marine life living on the seabed.

The Ministry of Primary Industries said more than 90 percent of New Zealand's offshore waters have never been bottom trawled.

Barry Weeber, who co-chairs the Environment and Conservation Organisation, has been a non-government representative at meetings of the South Pacific Regional Fisheries Management Organisation, including at the Hague in January.

Mr Weeber said bottom trawling was the undersea equivalent to felling trees to catch birds and was destroying sea-life.

"It is actually really destructive and the biodiverse communities that occurred on the bottom in the past have been heavily impacted by bottom fishing. That's why we want to protect those areas that haven't been impacted in the past but also those areas that have been, so we have some potential for recovery in the future."

Mr Weeber said the fishing industry has been lobbying for years to reduce conservation measures, while claiming what it is doing is sustainable.

He said he was disappointed the industry was not acknowledging its impact on the seafloor.

"Clearly if you're running big trawl nets and destroying what's there, that's not a sustainable industry. That's what they want to continue, they want to continue doing that on those high-biodiverse areas but also on the long-lived fish they're catching, the orange roughy."

Photo: RNZ / Dom Thomas

Stuart Nash said since he's been Minister of Fisheries, he's had over 1000 pieces of correspondence from all sectors with regard to fisheries.

Mr Nash said the government will not bow to pressure, and every decision they make will be based on evidence and science.

"I haven't had any pressure whatsoever put on me. There's a lot of work going on in the fisheries space at this point of time and everything has got to be based on the evidence."

Mr Nash said he planned to ask for a briefing on deep-sea bottom trawling.

The High Seas Group did not respond directly to RNZ, but in a statement Talleys deep sea manager Tony Hazlett said the group had been vocal in objections to aspects of conservation management measures.

He said permit conditions over the past decade had become increasingly onerous and Talley's supported the group's advocacy.