An environmental catastrophe has been predicted if authorities fail to deal quickly with the 1500 tonnes of fuel aboard the container ship stuck hard on Astrolabe Reef.
Tauranga Moana Fisheries Iwi chairman Brian Dickson feared a "major environmental catastrophe".
"We need to act as quickly as possible while weather conditions are favourable ... we should not be asking anyone's permission, we should just fire ahead and do it."
Mr Dickson, chief executive of Ngaiterangi iwi, feared the outcome could be massive contamination of the Bay of Plenty coastline, Tauranga Harbour and the Bay's off-shore fishing grounds and islands.
"It would have a long-term impact on the environment."
Mr Dickson said it was much more than the impact on the mataitai fishery reserve around Mauao - it threatened the traditional rights of Maori to gather kai moana (seafood) everywhere, including Motiti Island which was particularly vulnerable because of its close proximity to the ship.
Even Astrolabe Reef was a popular fishing ground for shell fish and fin fish, with Maori gathering a lot of paua, kina and crayfish around the reef.
Tauranga Green Party candidate Ian McLean said it was another example of how procedures were meant to be in place to stop things like this happening, but they still happened. "The risk is never zero."
He said information always trickled through slowly and authorities often responded a little bit too slow and a little too late.
Mr McLean wondered about the capacity of the oil spill management team to deal with a potential disaster on the scale of the Rena..
"With this country, you are only lucky with the weather for a short time. Clearly no one has found a way to get it off the reef and if it starts breaking up we are in big trouble."
A Tauranga maritime expert, who spoke on condition he was not identified, has urged authorities dealing with the stricken ship to put their focus on pumping the oil out of the Rena while the weather holds.
His appeal depends on bringing down the Ports of Auckland bunker barge Awanuia, which could comfortably take the whole 1700 tonnes.p> "The significant thing is to make sure that poxy oil does not wash up on the beaches," he said.
The expert said the situation with the ship looked bad and Maritime New Zealand needed to act now to get the oil off before winds got up next Monday and Tuesday.
The forecast was for reasonably settled weather until Monday when north-easterlies develop, freshening to 29km/h to 38km/h - strong enough to create difficult conditions for a ship stuck on rocks, and with the wind direction blowing an oil slick into shore.
Conditions are expected to worsen on Tuesday, with north-easterlies reaching 39km/h to 49km/h, and gusts possibly reaching 60km/h.
A spokesperson for Z Energy, which charters Awanuia from Ports of Auckland, told the Bay of Plenty Times it had not been asked to make the vessel available for getting fuel off the ship.
Jonathon Hill said the company was open to making the vessel available and staff were already thinking but had not heard from the salvage company.
The Tauranga expert, whose career included preparing for events like the Rena, said the situation was a major worry.
Getting weight off the ship would be a huge problem because a lot of the top rows of containers would be empty whereas the full ones were further down the stack.
He said Maritime New Zealand had to think in terms of what was the major risk. "Never mind the ship and the boxes [containers], the oil is the significant thing - get it off while the weather is good."
With 20 to 30 knot winds forecasted, he said Rena would starting grinding around on the reef and anything could happen. Oil booms would be useless once fuel started coming off the ship in large quantities in choppy seas.
The Awanuia was a manouverable vessel which could be put close enough to the vessel with the help of a tug to float hoses across.
The expert estimated the total operation would take about 12 hours, with Z Energy saying it would take about a day for the Awanuia to reach Tauranga.