Mauritius has arrested the captain of a Japanese bulk carrier that ran aground off its coast, causing an oil spill in one of the world’s most pristine maritime environments.

The MV Wakashio struck a coral reef on 25 July and began spilling oil on 6 August. The government announced a state of “environmental emergency” the next day.

Emergency crews managed to remove most of the ship’s remaining oil before it split in two on Saturday.

Police inspector Siva Coothen told Reuters: “We have arrested the captain of the vessel and another member of the crew. After having been heard by the court, they have been denied bail and are still in detention.”

The spill spread over a vast area of endangered corals, fish and other marine life, in what some scientists have called the country’s worst ecological disaster.

Scientists say the full impact is still unclear, but the damage could affect Mauritius and its tourism-dependent economy for decades. Removing the ship is likely to take months.