Every Sunday for the past seven months, about 60,000 live North American lobsters packed in wet newspapers and Styrofoam coolers make the 18-hour flight to Asia in a Korean Airlines cargo plane.

The 12,000-kilometer trip from Halifax, Canada, to Shanghai via South Korea has become a weekly routine this year with a surge in demand from China, where lobsters caught in North Atlantic waters are at least one-third the cost of competing supplies. As a result, exports have skyrocketed from Canada and the United States, the world's top producers.

With no lobster industry of its own, China had relied mostly on Australian imports to satisfy growing demand as its middle class expanded. When the catch began shrinking off Western Australia, and a 2012 glut in the Gulf of Maine sent prices plunging in the US that year, it became more attractive for the world's most-populous nation to buy from halfway around the world.

"When the domestic market collapsed, we looked farther and farther" for buyers, said Stephanie Nadeau, who shipped 1,130 metric tons last year by air to China for The Lobster Co in Arundel, Maine. "I never sold a lobster to China until 2010. It was the really low price and the dealer's desperation here because we had high catches and a god-awful economy. We had to move the lobster."

US exports to China rose to 8,560 metric tons last year, up 22-fold from 2009, US Department of Agriculture data show. Shipments already are up 12 percent this year.

It's easy to see why. Chinese importers shopping on Alibaba.com can buy live Canadian lobsters prized for their tail meat and big claws for $6 to $10 a pound, according to the website, compared with $20 to $33 for Australia's southern rock lobsters-a different species that doesn't have claws.

Increased demand from Asia provided a new outlet for US producers who saw prices drop after their catches expanded by 66 percent to 68,000 tons in the decade through 2013.

Buyers in Asia want their lobsters live at markets and restaurants. To survive the long trip, the sea creatures should arrive within 48 hours of being removed from water tanks, exporters say.

"You don't get paid for dead lobsters," Nadeau said. She added more refrigerated trucks and a storehouse in Canada with a tank to ensure stable supplies year-round, including during the busy Chinese New Year.