Mauritian volunteers fished dead eels from oily waters on Tuesday as they tried to clean up damage to the Indian Ocean island’s most pristine beaches after a Japanese bulk carrier leaked an estimated 1,000 tonnes of oil.

The ship, MV Wakashio, owned by Nagashiki Shipping and operated by Mitsui OSK Lines Ltd, struck a coral reef on Mauritius’ southeast coast on July 25 and began leaking oil last week, raising fears of a major ecological crisis.

Activists told Reuters that dead eels were floating in the water and dead starfish were marked by the sticky black liquid.

Crabs and seabirds are also dying.

“We don’t know what may happen further with the boat, it may crack more,” said clean up volunteer Yvan Luckhun.

The MV Wakashio is still holding some 2,000 tonnes of oil and it is expected to eventually break up, Prime Minister Pravind Jugnauth said late on Monday, warning that the country must brace for the worst.

Tourism is a leading part of the Mauritius economy.

The government, which declared an emergency on Friday due to the spill, is working with former colonial ruler France to try to remove the oil.