Originally published 2020-08-29.
Photos: Reuters.
In late August 2020, dead dolphins began washing up in the lagoons of south-east Mauritius, a few weeks after the bulk carrier MV Wakashio had run aground on a reef nearby and leaked about 1,000 tonnes of fuel oil. The first reports counted around 17 animals. Within three days the official tally had climbed past 35, and conservation groups later spoke of about 50 whales and dolphins.
Were they killed by the oil? The short answer is that it was never settled in public. Early government autopsies found injuries but no oil, a later laboratory test reportedly found hydrocarbons in one animal, and full results were not released. Here is what is known about the spill, the strandings and the arguments over the cause.
How the Wakashio spill happened
The Wakashio, a large Japanese-owned bulk carrier sailing under a Panamanian flag and operated by Mitsui O.S.K. Lines, struck a coral reef off Pointe d’Esny on 25 July 2020. Some early reports placed the accident in late June, but the grounding happened in late July. The ship was travelling empty, but it carried an estimated 3,890 tonnes of very low sulphur fuel oil for its own engines.
Oil began escaping on 6 August after the hull cracked. Prime Minister Pravind Jugnauth declared a state of environmental emergency and asked for international help. On 15 August the ship broke in two. Salvage teams had already pumped out most of the remaining fuel, but roughly 1,000 tonnes reached the sea, according to Wikipedia’s account of the spill. That figure is lower than the 1,200 tonnes quoted in some early coverage. On 24 August the bow section was towed out and deliberately sunk offshore, a decision environmental groups opposed.
Volunteers across the island responded by stitching floating booms from sugar-cane leaves, plastic bottles and even donated hair, to keep the slick away from the coast. Cleanup crews eventually worked along about 21 kilometres of shoreline.
Why the location mattered so much
The reef where the ship stranded lies close to Blue Bay Marine Park and the wetlands of Pointe d’Esny, which are protected under the Ramsar Convention, and to Île aux Aigrettes, a nature reserve where rare native species have been brought back from the brink. Conservationists describe the lagoon as one of the richest marine habitats in Mauritius, with hundreds of fish species, corals, seagrass beds and mangroves. Some scientists called the spill the worst environmental incident in the country’s history.
For a small island nation the damage was also economic. Tourism and fishing are central to the Mauritian economy, and the south-east coast depends on both. A polluted lagoon threatens not just wildlife but jobs, food and the country’s image abroad.
The dolphin strandings: what was found
The first carcasses appeared on 26 August on beaches near Grand Sable. Many of the animals were melon-headed whales, which, despite the name, are members of the oceanic dolphin family. They grow to about 2.75 metres, live in deep tropical waters and are known for strong social bonds and occasional mass strandings, as Wikipedia’s species profile notes.
The Mauritius Tourism Promotion Authority’s official update of 28 August listed 37 dead dolphins found in the south-east lagoon over three days: 18 on 26 August, nine on 27 August and ten on 28 August. Fisheries officials also reported about ten live animals that looked exhausted and could barely swim.
Preliminary autopsies by the government-run Albion Fisheries Research Centre found no hydrocarbons in the airways, skin, mouth or gut of the first animals examined. Their stomachs were empty, and most carcasses had serious jaw injuries and bite wounds. A fisheries official, Sudheer Maudhoo, suggested sharks might be involved, an idea critics rejected; bites on a weakened or dead animal do not explain why it died. Al Jazeera reported that the remaining carcasses were to be examined too.
Spill, scuttling or coincidence?
Three explanations were debated. Local oceanographer Vassen Kauppaymuthoo, who saw the scene, told the BBC that the animals smelled of fuel and warned that the situation would deteriorate. Environmental consultant and former MP Sunil Dowarkasing pointed to the timing, just after the bow was scuttled, and suggested that the sinking itself could have disturbed the animals, as well as the oil. He told Al Jazeera that islanders did not trust the official findings and that independent experts should carry out their own autopsies.
Others urged caution. Owen Griffiths of the Mauritius Marine Conservation Society told AFP, as quoted by Al Jazeera, that the deaths were “probably a very unfortunate coincidence,” noting a similar stranding in 2005. His theory was that the pod followed fish into the lagoon, could not find the way back out and injured itself on coral while exhausted.
In late September, Mauritian media reported that a forensic laboratory had detected hydrocarbons in a pregnant melon-headed whale. Greenpeace Africa said the government had not disclosed the laboratory’s conclusions and repeated, with the local group Dis Moi, its demand for an independent public investigation. The local organisation Eco-Sud had also asked to attend the autopsies and for results to be published.
Why the cause is hard to prove
Linking a stranding to an oil spill takes careful work: tissue tests for hydrocarbons, examination of lungs and stomach contents, checks for disease and parasites, and a comparison with what is normal for the species. Melon-headed whales strand in groups for many reasons, including disorientation and, in some documented cases elsewhere, underwater noise. Timing alone is a reason to investigate, not proof of cause. That is exactly why campaigners wanted every result published.
What happened next
Thousands of people marched in Port Louis at the end of August 2020 over the government’s handling of the disaster, in some of the largest protests the island had seen in decades. The ship’s captain and his second officer were later convicted in Mauritius and sentenced to 20 months in prison in December 2021. Mitsui O.S.K. Lines pledged about 1 billion yen (around $9 million) for environmental projects, and a Chinese salvage firm was contracted to cut up the stern section that remained on the reef.
Coral, mangroves and seagrass take years to recover from fuel oil, and long-term monitoring is the only way to measure the true cost. The episode left a clear lesson for coastal states: shipping lanes near fragile reefs need strong oversight, and when wildlife dies after a disaster, open and independent science is the best way to keep public trust.
Sources: MV Wakashio oil spill, Wikipedia; Al Jazeera: Calls for probe as dead dolphins wash up near Mauritius oil spill (26 August 2020); Al Jazeera: Mauritius says autopsy on dead dolphins finds wounds but no oil (27 August 2020); Mauritius Tourism Promotion Authority: MV Wakashio updates, 28 August 2020; Greenpeace Africa: reaction to reports of oil in a pregnant whale carcass (28 September 2020); Melon-headed whale, Wikipedia
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