WASHINGTON (AFP) -- World fish demand will soar by 2020, with supplies straining to meet a growing hunger for seafood in China and other developing countries, a report warned Thursday.

The world will eat 127.8 million tons of fish in 2020, up from 91 million tons in 1997 and 45 million tons in 1973, predicted the International Food Policy Research Institute (IFPRI) report.

Consumption in developing countries including China would jump 57 percent to 98.6 million tons in the 23 years to 2020, while edging up only four percent to 29.2 million tons in the developed world.

"The trends are clear: in 2020, people in developing countries will produce, consume and trade a greater share of the world's fish," said Chris Delgado, lead author of the report, Outlook for Fish to 2020.

Output from fish farming, or aquaculture, would have to soar to feed the expanding appetite because most of the wild fisheries were tapped to capacity or beyond, it said.

"The seemingly inexhaustible oceans have proved to be finite after all," the report said.

"Landings of wild fish have leveled off since the mid-1980s, and many stocks of fish are fished so heavily that their future is threatened. And yet the world's appetite for fish has continued to increase, particularly as urban populations and incomes grow in developing countries," it said.

By 2020, more than 40 percent of the appetite for fish would have to be met by fish farms, it said, predicting a doubling in aquaculture production from 28.6 million tons in 1997 to 53.6 million tons in 2020.

"With appropriate actions taken and investments made now, we can ensure that we will be able to meet growing demand for fish over the next two decades," Delgado said. "If policymakers focus on improving stewardship of marine and coastal resources, and developing technologies to reduce waste and environmental damage in wild fisheries, we will not only meet demand but we will do so in a way that is fair to the poor and environmentally sustainable."

China consumed 36 percent of the world's fish in 1997, more than tripling its share in 24 years. Outside of China, the developing world ate 33 percent of the world's fish harvest.

Developed countries, once the biggest consumers with 55 percent of the total pie in 1973, ate 31 percent of the total in 1997, the report said.

Besides being the biggest fish consumer, China was the world's predominant producer, the report said.

China boosted its share of world fish production to 36 percent from 10 percent in 24 years to 1997, and other developing countries increased their to 37 percent from 33 percent.

Developed countries' share of fish production, meanwhile, plunged to 27 percent in 1997 from 57 percent in 1973.