Japan's whaling fleet was followed by protesters to the Antarctic
Japan's whaling fleet has failed to catch its quota, after being disrupted by clashes with anti-hunting activists.
The fisheries agency said the fleet caught 60% of the minke whales they had planned - 551 from a target of 850.
The ships, which were followed around the Antarctic by activists, are due to return to port in the next few days.
The BBC's Chris Hogg, in Tokyo, said it was the first time in 20 years that protests had prevented the whalers from reaching their targets.
Japan's fleet set sail for the Antarctic last November. But officials said they lost 31 days of hunting as a result of the protests.
"Sabotage by activists is a major factor behind our failure to achieve our target," a fisheries agency official said.
Environmental group Greenpeace, which tailed the whalers for weeks, said it was disappointed the fleet had still managed to cull so many animals.
Greenpeace pointed out that this year's quota was much higher than in previous years.
Despite missing their target, this means the Japanese have still killed far more whales this year than three years ago, the group said.
The Sea Shepherd Conservation Society - which was involved in violent clashes with the whalers - claimed its campaign saved hundreds of animals.
At one point, Sea Shepherd activists threw bottles of foul-smelling substances at a whaling ship in an attempt to disrupt the hunt, resulting in three sailors complaining of eye irritation.
The incident followed a high profile stand-off in January in which two activists boarded another Japanese whaling ship.
The protesters were branded environmental terrorists by the Japanese.
As well as failing to reach its quota for minke whales, no fin whales were caught - though officials said that was because none were sighted.
Last year fewer whales were culled than had been planned because of a fire on one of the Japanese vessels.
Tokyo says it carries out whaling for scientific research, but critics say the same data can be collected without killing the animals.