Japan's Fisheries Agency made the announcement as the factory processing ship, Nisshin Maru, is steaming from the whaling grounds toward Drake's Passage near the tip of South America. It's being tailed by the Sea Shepherd vessel, Bob Barker.
Sea Shepherd Capt. Paul Watson, who is aboard the Bob Barker, issued a statement Wednesday that began: "I think it is premature to see this as a victory for the whales yet. There has been no mention of how long this suspension will be. It could be permanent, for this season only, or it could be for a matter of weeks or even days.
"What we do know is that the whalers will not be killing any whales for the next few weeks."
The whaling fleet also consists of three harpoon vessels. One has left the hunting grounds because of mechanical issues. The other two are useless without the ability to offload whales onto a factory ship.
If this year's hunt is, in fact, over, Japan has again fallen significantly short of its annual quota of 935 minke whales and 50 fin whales.
Jubilation is widespread among the environmental community. The Age, an Australian newspaper, quoted Patrick Ramage, director of the International Fund for Animal Welfare, as saying: "Under pressure from all fronts, the Japanese whaling fleet is apparently withdrawing early this season from the internationally recognized sanctuary around Antarctica.
"We hope this is a first sign of Japanese government decision makers recognizing there is no future for whaling in the 21st century and that responsible whale watching, the only genuinely sustainable use of whales, is now the best way forward for a great nation like Japan."
Japan, which claims whaling to be an important aspect of Japanese culture, has hunted the leviathans annually despite a ban on imposed on commercial whaling in 1986 by the International Whaling Commission. Japan has taken advantage of a "lethal research" loophole to skirt the ban, and says its hunts are for science.
Sea Shepherd activists, who this season have used three boats and several smaller inflatable vessels, had accompanied the whalers since New Year's Day. Their harassment techniques, which are controversial even among many opposed to whaling, have involved hurtling flares and stink bombs onto the whalers' decks and throwing ropes into their vessels' propellers.
The whalers, in a seemingly endless game of cat-and-mouse, have often responded by shooting at the activists with water cannons.
There have been no deaths or serious injuries attributed to the clashes, but they've become increasingly tense in recent years, and last year resulted in a collision that forced Sea Shepherd to scuttle the damaged boat, Ady Gil. An investigation of that incident determined that both captains were equally at fault.
Increased pressure from anti-whaling nations, including Australia and the United States, might also have factored into Japan's decision to quit early.
Japanese officials had, earlier this year, been in diplomatic talks with U.S. officials regarding the future of whaling. According to cables released by WikiLeaks, Japan had attempted to persuade the U.S. to punish Sea Shepherd by removing the nonprofit group's tax-exempt status as part of a compromise deal in which Japan would agree to reduce its quota.
There's also opposition on the home front, as the hunts are costly and demand for whale meat is shrinking, as fewer young people are eating whale flesh. Still, Japan has accused whaling opponents in the West of being hypocritical, claiming that minke whales are not endangered and that Western civilizations do their share of killing and eating animals.
The clashes between Sea Shepherd and the whalers have gained widespread exposure in recent years because of Animal Planet's "Whale Wars" series. A network film crew is with Sea Shepherd for a fourth season and the series will air in early summer.
-- Pete Thomas
-- Images showing clashes between Japanese whaling ships and activists are courtesy of Sea Shepherd
-- Editor's note: A version of this post appears on the GrindTv outdoors blog