Dolphins trapped in Taiji Cove in central Japan were killed on Tuesday (January 21).
Fishermen using nets and boat engines led the dolphins to an area, which was hidden from public view.
Blood seeped into the sea.
Activists from the Sea Shepherd Conservation Society denouncing the hunt said around 250 dolphins were trapped, with more than 50 selected for aquariums.
(SOUNDBITE) (English) SEA SHEPHERD CONSERVATION SOCIETY ACTIVIST, MELISSA SEHGAL, SAYING:
"A metal rod was stabbed into their spinal cord, where they were left to bleed out, suffocate and die. After a traumatic four days held captive in the killing cove, they experienced violent captive selection, being separated from their family, and then eventually were killed today."
Sea Shepherd says the slaughters occur almost daily for six months.
Japan has defended the dolphin hunt, saying it is a traditional industry and is carried out legally.
