A video capturing the final moments of a dolphin before it dies in Taiji Cove during Japan's controversial mass slaughter of the animal has been released by conservationists.

Each year the controversial dolphin hunting season sees fishermen on boats herd dolphins into the narrow cove in Taiji where they are killed by having a metal rod driven into their necks.

The best looking dolphins are separated and sold to aquariums.

In the video, Ric O’Barry - founder of The Dolphin Project and star of the 2009 Oscar-winning documentary The Cove - shows a panicked family of Risso’s dolphins swimming around in a sea pen, having been herded into the cove from deeper waters.

Their stress is evident as some of the dolphins tangle themselves up in the netted walls. Others attempt to swim beneath the nets but end up on the side closest to the shore instead of escaping into the open ocean.

One animal beaches itself on the rocky shore at O’Barry’s feet, rolling on its back as it tries to escape.

O’Barry can do nothing to help: "I will be arrested immediately," he says. "The police are all over the place."

Activists risk lengthy prison sentences if they interfere with the hunt.

Annual dolphin hunt in Taiji, Japan Show all 15 1 /15 Annual dolphin hunt in Taiji, Japan Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan A bottlenose dolphin was seen floating on back before slaughter Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Fishermen hiding their culture and tradition Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Remaining pod swims just a few feet from the slaughter of their family Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Dolphin drive out to sea Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Lathered in blood, fishermen receive more transfers of dolphin carcasses Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Fishermen enter the cove just after sunrise Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan A juvenile Bottlenose barely surfaces during drive out. The chances of survival are slim after 5 tormenting days in the cove Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Cove Guardians Jac and Ian document the slaughter Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan SSCS Cove Guardian Leader Melissa Sehgal interviews for CNN Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Fishermen in wetsuits hunt dolphins at a cove in Taiji, western Japan; U.S. ambassador to Japan Caroline Kennedy has expressed deep concern over the traditional dolphin hunt. Local fisherman corral dolphins in a secluded bay before killing many for meat Adrian Mylne/Reuters Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan The selection process of dolphins, during the annual dolphin hunt in Taiji. With 250 dolphins, this was the largest round-up in years Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan The agitated dolphins in the cove during the selection process. According to Sea Shepherd, Japanese fisherman rounded up more than 250 dolphins, including babies and juveniles Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan Japanese fisherman are shown in the cove. Taiji town claims the hunt is an important ritual dating back centuries Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan A rare albino calf swims close to his/her mother as the pod was herded into the cove. Dolphins captured in the cove are either sold into captivity, or slaughtered and sold for consumption, despite pleas from animal conservationists around the world against the event Sea Shepherd/EPA Annual dolphin hunt in Taiji, Japan The annual dolphin hunt in Taiji, Japan The process of selecting dolphins during the annual cull, which the mayor of the town defends 'on scientific grounds'

"This is anguish," O'Barry says, crouching down near the dolphin. "[He's] panic-stricken on the rocks, and I am heartbroken that I can't get in the water and help him away from ... he's tearing his skin up. This is awful."

Eventually, a boat of fishermen slowly makes its way over to the stricken animal. When they arrive, they grab the dolphin by its fin, pushing it out into the water.

“The dolphin’s not going to make it. He’s given up,” O’Barry says.

Moments later, the dolphin sinks to the bottom of the cove.

Game of Thrones actress Maisie Williams protests against the Taiji hunt in London in January 2015 (LEON NEAL/AFP/Getty Images)

O’Barry was shaken by the incident: "It breaks my heart," he says. "This is so stressful. This is so difficult to witness. I almost got in the water. I almost got in the water and maybe I should have."

"I guess I blew it," he adds solemnly, before turning the camera off.

The annual hunt has taken place since 1969 but was thrust into the public eye after footage from O’Barry’s 2009 documentary The Cove showed the water in the bay turning red with blood as the dolphins were slaughtered.