The Environmental Protection Authority is expected to make a decision on whether to allow a mining company to look for phosphate on seabed near the Chathams before Christmas.
The Hokotehi Moriori Trust presented its submission last week opposing the mining company's application, saying it could jeopardise 60 percent of New Zealand's commercial fishery.
The authority is considering an application by Chatham Rock Phosphate (CPR) Limited for a marine consent to mine phosphate from the Chatham Rise, which is used to make chemicals including agricultural fertiliser.
Closing submissions were heard today and would to continue being heard by the decision-making committee tomorrow in Wellington.
The last submissions were being presented by Forest and Bird, the Deepwater Group (fishing industry), the Crown, the Environmental Defence Society and Ngai Tahu.
Crown lawyer Jeremy Prebble today said there needed to be conditions which protected seabirds, marine mammals and the environment but first it wanted more information.
Greenpeace yesterday told the hearing mining would kill marine life and damage the environment.
Chatham Rock Phosphate will give its final submission tomorrow.
Once the hearing is formally closed, the committee has 20 working days to consider its decision.