Japanese fishermen drove a large group of dolphins into the shallows ... and, hiding from reporters and TV cameras behind a tarpaulin, killed at least 30 as the annual dolphin hunt that sparked protest in the West entered its final stages. Both the U.S. and British ambassadors to Japan have strongly criticized the drive killings" of dolphins citing the "terrible suffering" inflicted on the marine mammals. Every year the fishermen of Taiji, in western Wakayama prefecture, drive hundreds of dolphins into a cove, select some for sale to marine parks, release some and kill the rest for meat. On Tuesday, at least 30 dolphins out of the group of more than 200 held in the cove since Friday were herded by boat engines and nets into a killing area of the Taiji cove. Before the killing began, fishermen pulled a tarpaulin in front of the cove to prevent activists and reporters from seeing the killing. A large pool of blood seeped under the tarpaulin and spread across the cove. "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 Conservation Society activist Melissa Sehgal told Reuters. The annual hunt has long been a source of controversy and was the topic of "The Cove", an Oscar-winning documentary that brought Taiji into the international spotlight.