SINGAPORE – Many people living in South-east Asia often think they have to venture to Australia, the US or Japan to participate in whale watching tours, but such marine mammals can also be found in the waters in the region.

Singapore, too, is home to a few of them, including the elusive dugong and the Indo-Pacific humpback dolphin. In 2015, a dead sperm whale was even found in the waters off Tuas.

Mr Marcus Chua, who studies mammals at the NUS Lee Kong Chian Natural History Museum, said the presence of marine mammals shows that local habitats are able to support a population of large predators, or, in the case of the dugong, large herbivores.

Dr Louisa Ponnampalam, the co-founder of Malaysian marine mammal research and conservation group MareCet, added: “The significance of losing (marine mammals) would mean that their habitats can no longer support them.”

“We should be really concerned about our own future should we ever lose them, because it means the sea around us is no longer healthy, and we humans rely so much on the sea for so many things, whether we realise it or not,” said Dr Ponnampalam, who is also a Pew Marine Fellow.

To mark International Marine Mammal Protection Day on Feb 19, The Straits Times spoke with experts about South-east Asia’s marine mammals, the threats they face, and future research opportunities.

Where can they be found?

Marine mammals have been sighted across South-east Asia, one of the world’s marine biodiversity hot spots with more than 3,000 species of fish and 600 types of corals.

In September 2024, for example, a humpback whale was sighted in the waters off Pulau Redang in Malaysia. This was the species’ first sighting off the east coast of Peninsular Malaysia, according to MareCet.

A humpback whale was also sighted in January 2025 off the coast of the Philippines.

Various factors can influence the habitat suitability for the different species of marine mammals, said Dr Ponnampalam. They include:

• Depth
• Temperature
• Distance from shore
• Proximity to estuaries, which are coastal areas where a freshwater river or stream meets sa...