Militant anti-whaling group Sea Shepherd said Saturday the Japanese fleet had left the Antarctic whale sanctuary and appeared to be heading home with its smallest catch yet, hailing an "enormously successful" harassment campaign.
Sea Shepherd founder Paul Watson said this year would likely see the lowest haul by the Japanese whalers in history, with "no more than 75" of the mammals killed due to the group's efforts.
That compares with a catch of 267 last year -- 266 minke whales and one fin whale -- and is dramatically below the target of 935 minke whales and up to 50 fin whales set for this season by Japan's Institute for Cetacean Research.
"The entire Japanese whaling fleet is now north of 60 degrees and out of the Southern Ocean Whale Sanctuary," Watson said.
"Is whaling over for the season? We are not positive but we are 80 percent sure that it may be over," he said.
"This campaign will see the lowest take by the Japanese whaling fleet in the entire history of their Antarctic whale hunts."
Watson said the Korean-owned, Panamanian-flagged supply tanker the Sun Laurel was 48 hours from the factory ship Nisshin Maru, with a four-day return trip to the whaling sanctuary looking increasingly unlikely.
"This would leave about a week to kill whales and with the weather quickly deteriorating it would hardly be worth the effort."
Watson said Sea Shepherd had seen the Japanese kill just two minke whales, and they had only had two days of unobstructed hunting in the whole season, which began in late December.
"My conservative estimate of the number of whales killed this year is no more than 75. It could be much lower but certainly not higher," he said.
Watson described the campaign, in which each side accused the other of ramming attacks, as "enormously successful" and said Sea Shepherd would "continue to follow the whaling fleet north to ensure that they do not return to kill whales".
Despite several years of sustained harassment campaigns by Sea Shepherd and international condemnation, Japan continues to catch whales under a "scientific research" loophole in international whaling whaling bans.
It makes no secret of the fact that the meat ends up on dinner tables.
Fisheries Minister Yoshimasa Hayashi vowed last month that Japan would never stop whaling, describing criticism by environmentalists and nations including Australia as "a kind of prejudice against Japanese culture".
Australia has taken Japan to the International Court of Justice over its whaling programme, seeking an end to the so-called scientific slaughter.
Sea Shepherd has also been hauled before the courts, with a US judge banning the activists, in a December ruling, from physically confronting any vessel in the Japanese fleet.
They are also required to stay at least 500 yards (metres) from whaling vessels and prohibited from "navigating in a manner that is likely to endanger the safe navigation of any such vessel".
An appeals court last week labelled Sea Shepherd "pirates", clearing the way for the Japanese to pursue an injunction against their activities in the Southern Ocean, which were described as "violent acts for private ends".