Thousands of people on Saturday took to the streets of Port Louis, the capital of Mauritius, demanding an investigation into the oil spill from a Japanese ship that resulted in the death of at least 40 dolphins, The Guardian reported.

Demonstrators were seen on the streets carrying signs that blamed the government over its slow response to the disaster, according to AP. “You have no shame” and “I’ve seen better Cabinets at IKEA” were among the many posters that the protesters carried.

Meanwhile, Prime Minister Pravind Jugnauth blamed bad weather for the government’s slow response.

“We do not trust the government and the diluted information they’ve been feeding us regarding the management and responses to the oil spill,” Fabiola Monty, an environmental scientist, told the newspaper.

Last month, a Japanese ship Wakashio struck a coral reef, cracked and spilled around 1,000 tons of fuel oil into the marine region.

The Mauritius government has said it will carry postmortems on the dead dolphins and also formed two investigation teams to look into the incident. Veterinarians have so far examined two dolphins and said there were no signs of oil in their bodies, a preliminary report stated.

At the protest march, some speakers called for top officials in the government to resign. “One of the things that really binds people together is the sea,” writer Khalil Cassimally said. “It’s one of the jewels of this country, and everyone feels very passionately about this.”

Some experts said that water-soluble chemicals in the fuel were to blame behind the death of the dolphins. “Something that is also concerning is that we don’t know the possible long-term effects.” Jacqueline Sauzier, who works for the Mauritius Marine Conservation Society, was quoted by journal Nature. “The oil is a new low-sulfur fuel oil that is being introduced to reduce air pollution. This is the first time that type of oil has spilled, so there have been no long-term studies on the impacts.”

Similar protests were held outside the Mauritius High Commission in London, in Paris and Perth.

Various people, including the protestors, were also demanding inquiry into the reason the Japanese vessel strayed miles off course.

The ship was grounded on July 25 and began leaking on August 6 into the Mahebourg Lagoon. Civic volunteers tried to keep the ship afloat. Moreover, environmental workers ferried dozens of baby tortoises and rare plants to shore to minimise the damage. The vessel’s captain and first officer have been arrested.

Officials from Nagashiki Shipping, a ship owner, France and the United Nations are at the scene and multiple investigations are underway.

Another protest is scheduled for September 12.