Tokyo ? A fleet of Japanese whaling ships left for the seas of Antarctica amid protests Tuesday, aiming to kill 850 minke whales – almost double last year’s catch – and expand the hunt to fin whales for the first time.

The expedition is the first under a six-year research whaling program launched earlier this year by the Tokyo-based Institute of Cetacean Research, fisheries ministry official Kenji Masuda said. Japan wrapped up an 18-year study of feeding and migratory habits in March, when the fleet returned from an Antarctic hunt with a haul of 440 minke.

Their meat was sold to restaurants and food wholesalers.

Greenpeace International called on Japan to cancel the latest hunt, calling it commercial whaling in disguise.

The hunt, which is permitted as research under the rules of the International Whaling Commission, is expected to kill 850 minke whales and 10 fin whales, a rarer species.