Japan today cancelled the rest of its whale hunting season in Antarctic waters because of repeated harassment by Sea Shepherd activists at sea, after netting only a fifth of its targeted catch of 850 whales.

Conservation groups called today for Japan’s whaling fleet to turn back as the first ship set sail for the annual hunt in the Southern Ocean.

A fleet of six Japanese whalers left port today for their annual hunt in the Antarctic, where they hope to kill 860 whales for a controversial research programme.