The French Polynesian government says the salvage of the Chinese fishing vessel stuck on the reef of Arutua atoll for more than a month will be a difficult operation.
An assessment team examined the ship Shen Gang Shun 1 which had firmly stuck with 250 tonnes of fuel as well as about 70 tonnes of rotting fish on board.
The authorities said they would first have to set up a barrier to prevent any pollution of the lagoon.
Then they said they would have to remove the rotting fish which would take about four weeks because noxious gases in the hold are so potent that even masked people won't be able to be in there for more than two hours at a time.
The government statement said legal procedures had been initiated against the ship operator Shenzhen Shengang Overseas Industrial Company for being in possession of a protected species.
Earlier this month, environmental groups lodged a complaint after sharks were found in the ship which was in breach of the law as French Polynesia is a shark sanctuary.
Once the fish had been removed the 250 tonnes of fuel would need to be pumped out.
The government statement said afterwards the question would be whether to try to refloat the ship or to dismantle it.
It said within two weeks experts would be able to present technical options on how to proceed.