By Richard Black
Environment correspondent, BBC News website
The Nisshin Maru's departure from Innoshima was marked with a small protest
The Japanese whaling ship Nisshin Maru has reportedly left harbour for the annual hunt in Antarctic waters.
Greenpeace said the factory ship had left the port of Innoshima, near Hiroshima, without fanfare.
There was no official confirmation of the departure, although officials did say the number of whales targeted would be identical to last year's hunt.
An opinion poll commissioned by Greenpeace suggested that more Japanese support whaling than oppose it.
The Nisshin Maru and her fleet of catcher boats will attempt to catch about 935 minke and 50 fin whales during the Southern Ocean summer, under regulations permitting hunting for scientific research.
THE LEGALITIES OF WHALING
Under the International Whaling Commission's global moratorium on commercial whaling, hunting may be conducted in three ways:
Objection - A country formally objects to the IWC moratorium, declaring itself exempt. Example: Norway
Scientific - A nation issues unilateral 'scientific permits'; any IWC member can do this. Example: Japan
Aboriginal - IWC grants permits to indigenous groups for subsistence food. Example: Alaskan Inupiat
Usually the fleet's departure is marked with a ceremony. But a Japan Fisheries Agency official said that after protests last year, there would be no publicity this time due to "safety reasons".
The agency has also denied earlier reports that it would reduce its self-awarded minke quota.
The Sea Shepherd Conservation Society is aiming to disrupt the hunt again.
Last year's action, which included dowsing the decks of the Nisshin Maru with butyric acid, was largely responsible for the fleet catching little more than half of its minke quota.
A fire on board the factory ship caused a similar shortfall in the 2006/7 season.
But Greenpeace will not be there this time. The group says it is concentrating on campaigning in Japan rather than on the high seas.
Two of its leading activists, Junichi Sato and Toru Suzuki, are languishing in jail as a result of an attempt to highlight what the group claimed was the illegal disposal of meat from the Antarctic hunt.
Some anti-whaling academics have been advising that the traditional demonstration-based approach of anti-whaling groups is backfiring in Japan, allowing whalers to claim that the groups concerned are anti-Japan rather than anti-whaling.
"The obvious disarray within the whaling industry, and the extreme overreaction by the authorities towards Junichi and Toru, shows that Greenpeace's work in Japan is coming to fruition, by revealing the whaling programme as an expensive and embarrassing sham", said Jun Hoshikawa, Greenpeace's executive director in Japan.
The opinion poll which Greenpeace commissioned from the Nippon Research Center contains mixed news for the group.
It found that 31% of the Japanese population favoured whaling, while only 25% opposed it - the remainder being undecided.
However, the number in support has fallen from 35% two years ago; and almost half of the sample said they would favour whaling only around Japan, rather than on the high seas.
The Australian government, meanwhile, confirmed it was launching a programme of non-lethal whale research in the Southern Ocean which would involve collaborations with other countries.