A group representing the fishing industry is calling on a company that wants to mine for phosphate to come clean on the environmental impact it would have.
Chatham Rock Phosphate has applied to the Environmental Protection Agency to suck phosphate off the seabed at a depth of 400 metres between Canterbury and the Chatham Islands, a process the fishing industry says will harm fish stocks.
The company wants to mine a 450 square kilometre section of the seabed over a period of 15 years and says the phosphate would deliver an economic benefit of $900 million.
The Deepwater Group, representing deep-sea fishers, says the area is part of the Benthic Protection Area set up to allow hoki stocks to regenerate, and mining would jeopardise that.
Its chief executive, George Clement, says the company is withholding information about the environmental impact by refusing to release data requested under the Official Information Act.
He says the company is doing so on the grounds of commercial sensitivity but the group argues that's outweighed by public interest in protecting the area.
"Given the potential importance of the environment on the Chatham Rise, it's essentially the CBD of our deepwater fishing; the sooner we can be better informed as to the nature and extent of any environmental damage, the sooner that we can have an informed debate about the effects to our seafood production."
Mr Clement says the sediment that would be dumped back on to the sea floor during mining would smother the sea life the fish depend upon.