Teamwork helps protect giants of the deep

Majestic discoveries

According to the team's study, nine groups of sperm whales were sighted in northern areas of the South China Sea from 2019 to last year. They were seen southeast of the island province of Hainan and north of the Xisha Islands. Each group comprised five to seven whales, and seven groups were found to be nursing one or two calves.

Li said that throughout history there have been reports of stranded sperm whales sighted in China's coastal provinces, but until now scientists have been unable to directly confirm that there are sperm whale populations in the nation's coastal waters.

"When I first saw a live sperm whale in the South China Sea in 2019, I couldn't believe my eyes at first," Li said. "The sight of a single whale is breathtaking enough, but several times we saw a mother whale swimming with her calf, accompanied by a group of Fraser's dolphins. This was a sight to behold."

While adult male sperm whales travel thousands of kilometers looking for food and mates, females with their calves do not follow suit. Li said that coupled with the fact that the South China Sea has ample food sources for sperm whales, it is highly possible that it is also a key hunting and breeding ground for the creatures.

"As these whales are such an essential part of a healthy marine ecosystem, China may need to optimize its policies related to marine ecological protection to shield these valuable creatures and other undersea resources from intrusive human activities," he said.

Li said such work includes enhancing marine biology research in the South China Sea and establishing a national marine protected area to safeguard waters around sperm whale nurseries－similar to marine protected areas in countries such as the United States, United Kingdom, Greece, Australia and Brazil.

"For many countries around the globe, the sperm whale has been a flagship creature for marine research and a poster child for marine conservation," Li said.

"This is because sperm whales are peaceful creatures that do not compete with humans for resources on land－yet they play a crucial role in the sustainability of the oceans that benefits all of us. This makes them truly altruistic friends of humankind."

From ancient folklore to children's cartoons, the sperm whale has long occupied a space in human imagination－cementing its reputation as an amazing predator by regularly hunting adult giant squid hundreds of meters below ocean surfaces.

A sperm whale produces ambergris in its intestine－a rare, solid and waxy substance that is the product of undigested squid. Ambergris, one of the most sought-after ingredients for luxury perfumes, sells for $10,000 to $50,000 per kilogram, depending on quality－earning it the nickname "floating gold".

Li said sperm whales carry a large amount of nutrients, especially nitrogen, from the depths where they feed, bringing these substances back to the surface in the form of excrement when they emerge from the water to breathe.

Such waste stimulates the growth of phytoplankton－plankton consisting of microscopic plants－which not only absorbs carbon dioxide to produce oxygen, but also provides food for a wide range of sea creatures and greatly improves the productivity and sustainability of fisheries, Li said. "The sperm whale is like a giant gardener of the ocean," he added.

Adult sperm whales can weigh more than 55 metric tons and live for over 70 years. Due to their immense size and long life expectancy, the whales play a key role in the global carbon cycle, Li said. Although female sperm whales are typically smaller than males, the adults can still grow to more than 10 meters and weigh 10 to 20 tons.

"When large marine vertebrates such as sperm whales die, their carcasses sink to the seabed, providing a rich source of food for deep-water creatures and creating a micro-ecosystem for the otherwise barren ocean floor," Li said. "This is known as 'whale fall', and has been dubbed 'the most romantic death', as it allows many creatures to thrive in some of the most inhospitable places on Earth."

As a result, the sperm whale has become the focus of global marine research and conservation efforts, Li said. In 1975, Connecticut in the United States even designated the sperm whale as its official state animal.