Ocean expert Sylvia Earle has warned that crucial marine wildlife remains under threat, Chen Liang reports.

Sharks are in crisis and the oceans are in trouble, but the battle to save them is far from over, Sylvia Earle, a marine biologist, said.

The pioneering oceanographer, 79, made the remark in Beijing, where she launched Shark Protection in Action, a conservation initiative aimed at getting people and companies to pledge not to eat shark fin soup, a delicacy in China and other Asian countries.

"China is a uniquely important country. The people of China will determine so much of the future of our planet in the coming decades," she said in a speech at Tsinghua University on April 7. "That's why I am honored to be here and to have the opportunity to speak to you directly, about what I care about - the ocean, its iconic wildlife and the species that depend on it: That's us."

Earle, who has also brought out a Chinese version of her 2014 book Blue Hope: Exploring and Caring for Earth's Magnificent Ocean, described sharks as "some of the most magnificent fish" in the sea.

"Sharks have roamed the ocean for more than 400 million years," she later told China Daily. "Without sharks, the oceans will suffer."

In the last 60 years, humans have lost - "actually taken and eaten" - more than 90 percent of the world's big fish, she said, with about 100 million sharks caught and killed every year. "Sharks are in crisis. The ocean is in trouble."

China is the biggest consumer of shark meat, and according to estimates, the demand for shark fin has driven almost one-third of the world's shark species to the brink of extinction. Another 25 percent are close to being threatened.

The good news, Earle said, is that 10 percent of big fish still remain in the ocean. There is still time to turn things around, she said, "but not a lot". If things stay the same, she predicted, in a few decades sharks will entirely disappear.

"Chinese consumers can play an incredibly important role in saving the world's sharks from extinction," Earle said, adding that the Chinese government's decision in 2012 to ban dishes including shark fin and other wildlife products at official banquets was a great step forward.

Shark Protection in Action has been launched in partnership with Link Capital Nature and Social Affairs Center, a Beijing grassroots NGO, and United States nonprofit, the Pew Charitable Trusts.

In a packed lecture hall at Tsinghua University, Earle also had a discussion with actor and Earth Day ambassador Liu Ye, who appeared in the international hit Curse of the Golden Flower. He described Earle as an "idol and a source of inspiration", and admitted he used to eat shark fin soup before meeting his wife, who is French, in 2009.

"I've not eaten it since then," said Liu, now an ardent scuba diver.

Despite her age, Earle, who is explorer-in-residence for National Geographic, continues to spend three months a year on marine expeditions. Speaking about her most recent dive, in waters off Costa Rica, she said she saw few sharks. When she first visited in the 1970s, she said, they were "so common".

Although she has refused to eat fish for about 40 years, the oceanographer, fondly known as Her Deepness among admirers, said in Beijing that she resists telling people what they should or should not eat.

"It's a personal choice. But I have no problem with making them learn what the consequences of their choices might be. The biggest barrier to protection anywhere in the world is not knowing or understanding the consequences of your actions."

After hearing about media reports that China plans to expand its fishing operations and focus on the small crustaceans known as krill, she said, "It is ecologically dangerous."

Krill, she explained, are the cornerstone of the entire living Antarctica ecosystem, as they are one of the small organisms that can access phytoplankton - microscopic organisms that live in watery environments, both salty and fresh. Like land plants, phytoplankton have chlorophyll to capture sunlight, and they use photosynthesis to turn it into chemical energy. Krill feed on phytoplankton, converting it into a form suitable for many larger animals, including whales, seals, penguins and seals, for which krill make up the largest part of their diet.

"Never in the history of China or any other country until recent decades have krill been targeted for extraction from this amazing and very critical world," Earle said. "If you take them away, you take a critical link out of the system.

"What do seals eat? What do the whales eat? They need krill, we don't."

Contact the writer at chen-liang@chinadaily.com.cn