Japan's controversial whaling fleet in the Southern Ocean has failed to catch its quota. Its activities were disrupted by clashes with anti-hunting activists. The fleet has returned home after a troubled voyage. From Sydney, Phil Mercer reports.

The whalers are returning home after a five-month expedition to the icy waters near Antarctica. Their voyage was dogged by the presence of environmental activists out of Australia, who followed them for several weeks.

Japan's fisheries agency has said its fleet caught 60 percent of the minke whales they had planned to kill - 551 animals from a target of 850.

It was the first time in two decades that protests had prevented the whalers from reaching their target.

No fin whales were caught this year, although a quota of 50 had been set. Officials in Tokyo said the whalers never sighted any fin whales.

The whaling vessels set sail for the Southern Ocean last November. Japanese officials say they lost 31 days of hunting because of disruptions caused by activists from Greenpeace and the Sea Shepherd Conservation Society. Japan calls their actions as "sabotage."

Nicole Beynon of the Humane Society International in Australia is confident that Japan's annual whale hunt will soon be abandoned.

"I think if the pressure can stay on the Japanese government for a few more years we will get to that point," he said. "The industry is financially not doing well. It is heavily subsidized by the Japanese government. The Japanese public are [is] starting to question those subsidies and I think it is a matter of time before both international pressure and commercial forces will see an end to this industry."

Greenpeace says it is disappointed the Japanese fleet had still managed to kill so many animals.

Environmentalists say that despite missing their target, the hunters harvested more whales this year than they did three years ago.

A spokesman for the Sea Shepherd Conservation Society - whose protest ship was involved in a series of high-seas clashes with the Japanese fleet - says its campaign saved 500 whales.

Commercial whaling is banned under international agreements. Japan says it hunts whales for scientific research. Critics believe the same information can be collected without killing the animals, and point out that the whale meat Japan harvests is sold to the public.

Australia sent a customs vessel to monitor the Japanese fleet to gather evidence for possible international court action. Canberra is a vocal critic of the annual hunt, calling it an unnecessary slaughter.