China and the United States launched a joint initiative Wednesday to protect the oceans, highlighting such cooperation as proof the two nations can work together despite stubborn disagreements.

US Secretary of State John Kerry and State Councilor Yang Jeichi chaired the first meeting of a new oceans working group, on the third and final day of key annual talks between Beijing and Washington.

"Once again we're breaking new ground with respect to China and the United States' ability to find an area in which we can cooperate, which has major significance... for people everywhere," Kerry said.

Some 400 Chinese officials have been visiting Washington since Sunday for the yearly strategic and economic dialogue, a forum for the two uneasy partners to try to manage their increasingly complex ties.

China and the United States are two of the top fishing nations in the world, Kerry said, and also leaders in ocean science.

"So we have a real opportunity here to be able to come together... to deal with conserving and protecting the oceans," he said, adding it could be "a centerpiece in the newly defining relationship with China."

Yang agreed, saying the oceans were "a shared homeland of mankind, vital for our survival and development."

Even though the world's two leading economies remain at odds over some aspects of maritime policy -- in particular Beijing's territorial claim to most of the South China Sea -- Kerry said "in the marine environment there is an urgent need for our countries to step up and help lead."

"The oceans are part of us, all of us," Kerry insisted, saying "we need to heed carefully the responsibilities that we have."

- Pristine wilderness -

Beijing and Washington are working together to try to create a marine protected area in Antarctica in the Ross Sea, he said, referencing one of the world's last true wildernesses.

The United States has long sought to create a marine reservation in the Ross Sea stretching across 1.34 million square kilometers (517, 400 square miles) in an area often referred to as the "Last Ocean" due to its pristine condition.

Environmentalists say the Southern Ocean is home to more than 10,000 unique species, including penguins, whales and colossal squid.

But to the dismay of environmentalists, China blocked the move at a meeting in Australia last year.

The two countries have also agreed to step up cooperation in combatting illegal wildlife trafficking.

A new poll released this week by the Pew Research Center shows that the US bid to pivot more towards Asia has won general support on both sides of the Pacific.

The US is also still seen as the world's top economic power, even more so than last year. But 48 percent of 45,435 people surveyed across 40 nations believe that China will eventually replace America as the world's leading super power.

- Transparency -

On their burgeoning economic ties, the US side stressed the need for transparency and proper regulation for businesses.

China is the fastest-growing source of foreign direct investment in the United States, and in 2014 US exports to China reached $124 billion, making it America's third-largest export market.

"A key ingredient is regulatory rule making that is transparent, predictable, and open to stakeholder input," said Treasury Secretary Jacob Lew at a roundtable with top chief executives from Chinese and American companies.

"It is also of vital importance that there are non-discriminatory technology policies and open trade in information and communications technology goods."

Vice Premier Wang Yang, speaking through an interpreter, said business investment was an important part of the relationship.

"There are still problems and obstacles, and these require new ways of thinking," he said.