March 24 (Bloomberg) -- The blue whale, the largest animal on Earth, may be saved from extinction with help from an ocean- fertilization experiment in the seas off Antarctica that has sparked growth of its main food source.

Dumping a by-product of metal processing, iron sulfate, into the ocean stimulates the growth of plankton, which is consumed by krill, said Victor Smetacek of Germany’s Alfred Wegener Institute for Polar and Marine Research. Adult blue whales eat about 4 tons of the shrimp-like animal daily.

“Fertilizing the feeding grounds is analogous to creating water holes in the desert,” Smetacek, who led a research expedition to the South Atlantic this year to test a theory that fertilizing the ocean can help reduce carbon-dioxide emissions, said yesterday in an interview. “It’s ecosystem restoration.”

The blue whale, which averages 25 feet (7.6 meters) at birth, is listed as endangered by the International Union for Conservation of Nature of Switzerland. Japan conducts an annual hunt in the northern Pacific and Southern Ocean using a loophole in a 1986 global whaling moratorium that allows “lethal research” on whales.

What Japan’s government refers to as a research hunt began in 1987 and kills minke and fin whales. Japan’s plan to hunt humpback whales was postponed in 2007 after protests from New Zealand and Australia. The program also takes skin and blubber samples of blue and other whales using non-lethal methods.

The population of blue whales, which can reach 105 feet in length with tongues weighing as much as an elephant, has declined up to 90 percent the past century, the IUCN said. Blue whales were heavily hunted until a worldwide ban in 1966.

“We have a solution to saving the whales -- why wouldn’t we want to use it?” Smetacek said in Berlin.

Conservationists Balk

Conservationists today questioned whether staving off the extinction of blue whales, which can weigh about 200 tons and have an average lifespan in the wild of 80 to 90 years, is simply a matter of dumping iron sulfate in the ocean.

Fertilizing the seas with iron may even violate international agreements on marine protection, said Stephan Lutter, a marine policy expert at World Wildlife Fund in Hamburg. Promoting algae growth with fertilization can also result in eutrophication, or a proliferation of plant life that reduces oxygen content in water and eliminates other sea life.

“It’s much more essential to solve the significant impacts of humans on the ocean environment, like overfishing and habitat destruction,” Lutter said in a telephone interview.

Spurs Algae Growth

In the experiment, Smetacek’s team of 48 scientists from Germany, India and other countries dumped six tons of dissolved iron sulfate in a 300 square-kilometer (116 square-mile) part of the Southern Ocean, spurring rapid growth of the area’s algae.

The test successfully reduced CO2 emissions in specific areas with high amounts of silicic acid, crucial in the construction of algae cells. Using the technique as a large- scale means of reducing emissions of greenhouse gas in the atmosphere “makes no sense” due to high costs, Smetacek said.

Researchers around the world are studying ways to counter global warming and climate change, which scientists say is worsened by industrial emissions of carbon dioxide in the air from coal plants and other sources.

In December, negotiators from about 190 countries are to meet in Copenhagen for UN climate talks to finalize plans for reducing CO2 emissions from cars, factories and planes. One proposal includes using carbon credits from projects that absorb the gas or generate energy with less pollution.

To contact the reporter on this story: Jeremy van Loon in Berlin at jvanloon@bloomberg.net.

Last Updated: March 24, 2009 07:40 EDT