"There is other evidence of ongoing and increasing exposures to hydrocarbons over time in economically and environmentally important species like golden tilefish, grouper and hake."

In 1978, a large crude oil carrier ran aground off the coast of Brittany, France, which leaked nearly 70 million gallons of oil into the sea.

Around 200 miles of the French coast were polluted by the oil slick, and it killed millions of invertebrates, such as molluscs and crustaceans. The spill also killed an estimated 20,000 birds and contaminated oyster beds in the region.

Experts say that despite best efforts, generally less than 10% of oil spilt in incidents like these is successfully cleaned up.

France has sent a military aircraft with pollution control equipment from its nearby island of Réunion to help with the Mauritian spill, while Japan has sent a six-member team to assist the French efforts. The Mauritius coast guard and several police units are also at the site in the southeast of the island.

"The Mauritian government should do the environmental impact assessment as soon as they can," said Professor Steiner.

"The impact is likely to remain for years."