Tokyo, Japan (CNN) -- Cornered by fishermen, divers and boats, the bottlenose dolphins splashed frantically as they tried to escape their human captors in the infamous cove in Japan.
Appearing severely stressed, some even tried to jump over partitions and flailed as they got tangled in nets, as seen through a live stream provided by the marine life group, Sea Shepherd Conservation Society.
Dolphins separated by nets into smaller partitions bobbed up and down, trying to reach other members of their pod. The environmental group said that the dolphins appeared bloodied and they've had nothing to eat for more than 72 hours while trapped in Taiji Cove.
Many in Taiji view the practice as a legal tradition.
For a fourth night, more than 200 dolphins will remain trapped, where several of them are likely to be slaughtered Tuesday, according to the environmental activists who have been monitoring activities in the cove in southwest Japan.
The annual event is a focal point of the Taiji community's dolphin hunting season.
Although the hunting of dolphins is widely condemned in the West, many in Japan defend the practice as a local custom -- and say it is no different to the slaughter of other animals for meat.
Kazutaka Sangen, the mayor of Taiji defended the practice as legal.
"We have fishermen in our community and they are exercising their fishing rights," he said. "We feel that we need to protect our residents against the criticisms."
He accused the Sea Shepherd of using the issue of dolphin hunting to raise funds and attract attention. The Sea Shepherd Conservation Society has been live-streaming video of events in the cove and posting frequent updates on Twitter.
The Wakayama Prefectural Government, where Taiji is located, gives an annual "catching quota." This year, the government allows for the hunting of 2,026 small porpoises and dolphins (557 are for bottlenose dolphins).
The dolphin hunt has seen some changes, Sangen said. The town wants to create a whale/porpoise study with the aim of bringing a marine park to the city. And the method of hunting has been changing, becoming less crude, he added.
On Monday, the fishermen focused on selecting dolphins to be sold into captivity at marine parks and aquariums in Japan and overseas, the conservation group said.
Trainers marked the dolphins deemed unsuitable for captivity with a white mark. Those dolphins bearing the mark are likely to be killed Tuesday and some will be driven back out to the ocean, according to the group.
Kennedy's tweet met with criticism in Japan
Caroline Kennedy, the recently installed U.S. ambassador to Japan, tweeted that she is "deeply concerned by inhumaneness of drive hunt dolphin killing."
While Japanese media did not cover the dolphin hunt, several outlets reported on Kennedy's comments. On social media, Japanese users blasted Kennedy for commenting on what many consider a tradition.
One user, named @simaya tweeted: "She refers to humanitarian treatment to animals. What about the atomic bombing, Agent Orange and missiles falling on civilians in the Middle East?"
Masayhisa Sato, a Japanese lawmaker tweeted: "The dolphin hunt is also a traditional fishing culture. I wonder whether it's appropriate for ambassador to comment on this."
Dolphin slaughter looms
On Monday, divers and boats drove the dolphins into increasingly small segments of the water to select the ones that will be held in captivity.
About 40 to 60 local fishermen work with nets to divide up the dolphin pod, initially estimated by the Sea Shepherd Conservation Society at more than 250.
"They tighten up the nets to bring each sub-group together then the skiffs push them toward the tarps. Under the tarps in the shallows is where the trainers work with the killers to select the 'prettiest' dolphins which will sell and make the best pay day for the hunters," the group said.
"But the process is brutal and stressful. Some of them die from injuries incurred during the manhandling or simply the stress."
Dozens of men circled around dolphins pinning them against a boat, wrestling and hoisting them into black nets by pulling on their dorsal fin. When men successfully captured the dolphins into the net, they cheered "Yay!"
The Cove Guardians counted 51 bottlenose dolphins taken in the last three days.
The dolphins that have not been selected for captivity will face an uncertain fate -- some will be killed and others will be freed.
Once the slaughter begins, it will turn the water in the cove red with blood, as documented in footage captured by the Sea Shepherd Conservation Society in the past.
The fishermen will "kill the 'undesirable' dolphins (those with nicks and scars) under the tarps to hide from our cameras when that time comes," the group said. Large, tan-colored tarps have been installed at the cove, as seen through the Sea Sheperd's live stream.
Japan at center of controversy
A 2009 Oscar-nominated documentary film, "The Cove," brought the issue of dolphin hunting in Taiji to the fore with bloody scenes of dolphin slaughter.
The prefecture government has condemned the film in an online response as distorted, biased and unfair to the fishermen. "'The Cove' filmed secretly the scenes of dying dolphins, and depicted their death in a manner designed to excite outrage," according to the Wakayama Prefecture statement.
"The Taiji dolphin fishery has been a target of repeated psychological harassment and interference by aggressive foreign animal protection organizations," it said.
The Japanese practice of whale hunting has also put it in conflict with the views of much of the world.
Earlier this year, Sea Shepherd said it had chased Japan's whalers out of Antarctic waters. Japan's fleet carries out an annual whale hunt despite a worldwide moratorium, taking advantage of a loophole in the law that permits the killing of the mammals for scientific research. Whale meat is commonly available for consumption in Japan.