Japan has confirmed that it will carry out its largest whaling programme in the South Pacific.
The mission, expected to draw strong protests from environmentalists, will depart on Sunday and breaks a 44-year moratorium on hunting humpback whales.
Japan's fisheries ministry said the fleet had instructions to kill up to 1,000 whales, including 50 humpbacks.
Japan was forced to abandon commercial whaling in 1986, but has since carried out whaling for "scientific research".
Four whaling ships, including the lead craft Nisshin Maru, will depart from the southern port of Shimonoseki.
The 239-man mission plans to kill more than 900 minke whales as well as fin whales and humpbacks, in a South Pacific whale hunt that will run until mid-April.
The 8,000 metric tonne Nisshin Maru was crippled by a fire on a whaling mission in the Antarctic in March. One crew member was killed.
A Greenpeace campaign ship will be following the Japanese fleet.
Tokyo's plan to target the humpback - which was hunted to near extinction four decades ago - has drawn condemnation from environmentalists.
"Humpbacks are very sensitive and live in close-knit pods. So even one death can be extremely damaging," Greenpeace spokesman Junichi Sato said.
Japanese fisheries officials insist both humpback and fin populations are back to sustainable levels.
"Humpback whales in our research area are rapidly recovering," fisheries spokesman Hideki Moronuki said.
"Taking 50 humpbacks from a population of tens of thousands will have no significant impact whatsoever," he said.
Mr Moronuki said killing whales allows marine biologists to study their internal organs.
Meat from Japan's scientific catch is sold commercially but Japanese officials deny that the mission plans to make a profit.
Japan argues that whaling is an ancient Japanese tradition, and has pushed unsuccessfully at the International Whaling Commission to reverse the 1986 moratorium on commercial whaling.
Environmentalists say Japan's research programme is a pretext for keeping the whaling industry alive. ( BBC )