The seafood industry has weighed in with a strong submission against Golden Bay-based Chatham Rock Phosphate's application to suction-mine the Chatham Rise.
Submissions to the Environmental Protection Authority closed yesterday, with the Deepwater Group, representing 95 per cent of fish quota beyond coastal waters, saying the mining would have "significant and irreversible adverse effects on the marine environment".
Impacts would include "massive disruption" to the seabed and the destruction of fauna on it, including protected corals, the group says.
The application pits one extractive business against another, with the seafood industry saying its harvesting is sustainable in the foreseeable future while CRP's plan is for one-off removal over only 15 years.
"Chatham Rise is home to New Zealand's most productive and abundant deepwater fisheries and is recognised as a ‘hotspot' habitat for juvenile fish including hoki, ling, silver warehou and white warehou," Deepwater Group chief executive George Clement said.
Mining had the potential to impact on fisheries well beyond the area.
"Almost all of our juvenile hoki live on the Chatham Rise. When they mature they move on to other feeding and breeding grounds around New Zealand. If the nursery environment for these young fish is adversely affected by mining, there will be fewer hoki and catches will be reduced across the entire New Zealand zone."
The group's submission says downstream effects would include changes to water quality as a result of the release of trace metals and other contaminants. Combined with "widespread habitat destruction", this would put the health and quality of New Zealand's sustainable fisheries at risk.
CRP has repeatedly said the effects of hoovering up phosphate
nodules from the sea floor 450 kilometres east of Christchurch would be minor and only affect a small part of the Chatham Rise, which is between Canterbury and the Chatham Islands.
But Clement labels the plan "large-scale strip mining" and says the area under claim for mining is equivalent to all of the North Island south of Foxton, most of it not yet harmed by human activities.
"People in Auckland and Wellington wouldn't want strip mining in the space where they live, and we don't want it in the nation's CBD for seafood production," he said.
The difference is explained by the fact that while CRP has a mining permit for only 820 square kilometres, and intends to mine 30sq km a year to meet its annual target of 1.5 million tonnes of phosphate nodules, it is seeking marine consent for the total Chatham Rise: 10,192 sq km.
Its application says the remaining area could be mined in future depending on research results and obtaining relevant mining permits.
If the mining is approved, it would be the first in water at such depth - 250 to 450 metres.
CRP has said the mining would benefit New Zealand by $900 million over 15 years.
"This is a one-off gain and one that will leave the seabed turned upside down," Clements said. "During this period seafood from the Chatham Rise will earn New Zealand in excess of $2500 million, and this revenue doesn't just end in 16 years' time."
New Zealand-listed CRP, part-owned by Dutch dredging and shipping giant Royal Boskalis and American venture capitalists, intends to suck up sand, silt and phosphate nodules from gravel to tennis ball-sized lumps for sale, unprocessed, to the fertiliser market in New Zealand and overseas. It believes the resource is worth $6 billion, and has forecast earnings of $62m to $100m a year for 15 years.
It is run from Golden Bay and an office in Wellington by managing director Chris Castle and corporate affairs director Linda Sanders, who have other mining-related interests.
Hearings, likely to take place in Wellington and the Chatham Islands, are set to begin on September 4, with a decision expected by the end of November.