On one side is the Otakou runanga, the driver of a mataitai for Otago Harbour, and on the other, Southern Clams, which recently began commercially harvesting clams from the harbour.
A mataitai, if approved by the Minister of Fisheries, would prevent commercial fishing in Otago Harbour.
The company began harvesting cockles in mid-September, prompting Otakou runanga customary fisheries manager Hoani Langsbury to liken the practice to Japanese whaling.
Fuelling the tension between the groups is research by a former University of Otago PhD marine science student, Craig Irwin, concluding the commercial harvesting of cockles appeared unsustainable.
Mr Langsbury said Mr Irwin's research supported what "we know anecdotally - the harvesting of cockles (tuaki) in Otago Harbour is unsustainable".
He said the harbour had been closed to commercial fishing for three decades and it was disappointing to see cockles taken from the middle banks being exported overseas under the guise of research.
Despite Southern Clams knowing about the research - which it funded - the company chose not to pass on the findings to the ministry or consultants employed to research the fishery stock, Mr Langsbury said.
Southern Clams director Roger Belton confirmed the company commissioned and paid for the research but rejected claims it did not pass the research on to interested parties.
"We pass on research to anyone who wants it."Mr Belton said he did not have a problem with most of the research findings, but its conclusions were"erroneous".
The research was conducted at a time when cockle numbers were low, and further research was under way as part of the five-year research permit, which entitled the company to 650 tonnes a year.
The company's livelihood depended on the sustainability of the fishery and more information was required to reach an appropriate conclusion - a point backed up by the research, he said.
Efforts to contact Mr Irwin overseas were unsuccessful.
However, Dr John Jillett, a former associate professor at the university and the internal examiner of Mr Irwin's 2004 thesis, said the research was "comprehensive on the question of the effects of harvesting on cockle population".
The research raised the question why the company was granted a scientific permit to take "huge quantities of cockles" from Otago Harbour, if the fishing stock of Papanui Inlet (now closed due to sanitary problems) and Waitati was "not what it was".
"I think the research has been inconvenient to [Southern Clams'] interests," Dr Jillett said.
Asked if his company was running down the fishing stock, Mr Belton replied: "Why the hell would we?".
Mr Belton said any concern over the sustainability aspects of the research was "pure politics", and the runanga was jealous of the company operating in an area where Ngai Tahu had quota.
While Southern Clams supported the original concept of a mataitai, it did not support the reserve being widened to include the whole harbour and this had created tension between the groups.
Mr Langsbury said Ngai Tahu chose not to fish its quota and had elected to enlarge the mataitai at the request of the wider community.
A decision on the mataitai was not expected to be made until next year.
