Scientists in Japan, where whale meat is a traditional food, are experimenting with "farming" the giant mammals in freshwater lakes.

"Whales are, so to speak, cattle in water without feet," says Hisao Izawa, a professor of veterinary medicine at Hokkaido University and the leader of a group experimenting with the idea.He rates the chances of success as high as 50-50 because of similarities between cattle and whales. "Their stomachs and kidneys are very similar," Izawa said.

Feeding is a major problem because whales, which can weigh many tons, eat as much as four percent of their weight every day - usually either fish or plankton, microscopic organisms.

However, the scientists plan to feed the creatures on grass by implanting in their stomachs a cellulose-digesting microbe found in the stomachs of cattle.

The results, the scientists say, will be plentiful whale meat and the possible development through breeding of a "dairy whale."

Whale meat is a traditional dish in the Japanese diet but has become scarce and expensive with the near worldwide ban on whaling. There is no market yet for whale milk, but the scientists think one could be developed.

The scheme could also help to preserve endangered whale species through artificial insemination.

The farms are also potential tourist attractions, the scientists say.

The group began their experiments in June by trying to accustom dolphins, closely related to whales, to life in fresh water. The mammals were put in seawater in a Hokkaido University pool and the salt density of the water was gradually decreased from about four percent to zero.

Three dolphins lived normally in the fresh water for a week before developing wrinkles on their skin and losing their appetite. The salt density was returned to two per cent.

The experiment will continue at a slower rate of dilution over about three years. If successful, the group plans to use the same method with minke whales.

There is some concern, however, that the whales may never get used to fresh water.

"Whales gradually adapted to the sea over tens of millions of years and this fact should be respected," said Kiyoharu Ohsumi, head of the Far Seas Fisheries Research Laboratory of Japan's Fishery Agency.

Suitable lakes also need to be found for the farms.

Naie-cho, a small town in Hokkaido prefecture in the north, has offered the use of one which will be formed in 10 years with the completion of a dam.