The company which given a permit to mine part of the Chatham Rise seabed for phosphate says the area it is planning to target will not have an impact on hoki fish stocks.
A fishing industry lobby group says the seabed is a significant nursery for juvenile hoki, and if it is damaged the hoki fishery could be compromised. The Deep Water Group says the mining method that involves dispersing sediment back onto the sea floor would be destructive.
But Chatham Rock Phosphate chief executive Chris Castle says its research, carried out at a cost of $20 million, has found the hoki fishery will not be affected.
He says the fishery is spread over 200,000 square kilometres and Chatham Rock Phosphate will be operating in only 30 square kilometres each year.
Mr Castle says while the permit allows for an 820 square kilometre area to be mined, the intention is to mine just 450 square kilometres over 30 years.