In shark-infested waters off the Australian island of Tasmania, Dean Lisson spends five hours a day diving for abalone.

Dodging the sharks is his first challenge. Getting the catch alive to hungry Chinese diners is the next.

Live sea snails that cost A$40 ($31) a kilogram in Australia change hands for A$60 a kilo in Hong Kong, said Lisson. The chewy flesh is a prized ingredient in traditional Chinese cuisine. Cathay Pacific Airways Ltd, Singapore Airlines Ltd and Qantas Airways Ltd are filling up their luggage holds carrying seafood on the 8,000 kilometer journey.

"We want to get it to the market in the best possible condition," says Lisson. "The live product is at the premium end: you've got to look after it."

Australia sends about A$1.6 billion of food overseas by plane each year, making it the country's biggest airborne export after gold and medicine. The trade in abalone and rock lobster alone was valued at about A$761 million in the 12 months ended June, according to government data - up about 31 percent from the A$581 million total three years earlier. Nearly 90 percent of the country's seafood is exported by air.

Exports to China of the two shellfish are worth more to Australia than those of wine or dairy products, according to the Abalone Council, an industry group. They'll benefit further from a free-trade deal signed in November that will cut China's tariffs from 15 percent to zero by 2018.

The agreement "will open up the market for us", Nigel Chynoweth, Australia cargo manager at Cathay Pacific, says, allowing the carrier to supply smaller cities in western and northeastern China from its Hong Kong hub.

Cathay currently carries as much as 20 tons per flight of lobsters from Perth airport and charges four to five times more to ship seafood than it does for fruit and vegetables, he says. The export growth has been driven by growing Chinese wealth and changing consumer tastes, as well as improvements in the airborne supply chain, he adds.

"The Chinese population is becoming more worldly in terms of appreciation for this product," Chynoweth said, referring to lobster. "It's not just in the high-end restaurants."

Abalone (as shown in picture above) is a prized ingredient in Chinese cuisine - one of nine seafoods, including shark's fin, sea cucumber, and cuttlefish roe, described in the Garden of Contentment, a culinary classic by 18th century poet and gourmet Yuan Mei.

The most-prized variety is still the dried abalone produced around the northern Chinese port of Dalian, according to Mark Wang, executive sous chef at Shanghai's Fairmont Peace Hotel.

Drying produces about 200 grams per 1.5 km of fresh meat, which then has to be soaked and braised in a "very complicated production process" taking as long as a week, he says.