An Australian-led organisation has launched a world-first legal challenge against the controversial Taiji dolphin hunt in Japan in a bid to stop it once and for all.

Last Wednesday, Action for Dolphins – formally Australia For Dolphins - submitted evidence alongside Japan’s NGO Life Investigation Agency.

The case has been six years in the making.

The two not-for-profits are arguing the drives are in fact illegal under Japan’s own animal cruelty laws, and have submitted evidence Taiji fisherman are going over the mandated council quotas.

Fishermen on boats go over bottlenose dolphins in Taiji, western Japan. (Sea Shepherd/AAP)

“The dolphins aren’t being rendered unconscious before being killed,” CEO of Action for Dolphins Sarah Lucas told nine.com.au .

“Japan’s main animal protection legislation is called the Animal Welfare and Management Act, which says you cannot inflict undue cruelty or injury on animals. There’s also standards for slaughtering called the Culling Standards that set out that animals have to be made unconscious before they’re killed, so they don’t suffer.”

The current method of killing , which is deemed humane by the government, requires the dolphin’s spinal cord be cut before it is killed. This involves the repeated insertion of a metal rod followed by the plugging of the wound to prevent blood loss into the water.

“We can say categorically that this method of killing causes enormous suffering to the animals. Not only is it not humane, it’s the least humane way to kill these animals,” Lucas said.

“The problem is the spinal cord is protected, it’s wrapped up in vertebrae and the bones protect the spinal cord.

“There is only one tiny gap in the bone, if you were to get the rod exactly in that position, with enough force, and the correct trajectory to completely sever the spinal cord then the animal would be unconscious.

“But because there’s no external landmarks to tell where that position is, they must guess where to put the rod. In Taiji the animals are thrashing around and moving their heads violently, so the chances become even more minute.”

However, Taiji fisherman defend the hunt as tradition, and Taiji Mayor Katzutaka Sangen has said they will not change plans based on the criticism of foreigners.

The hunt, subject of the Academy Award winning documentary The Cove , runs from September through to February each year.

Dolphins are either killed for their meat or captured for live trade.

Dolphins perform during a "dolphin show" at Niigata City Aquarium in Niigata on May 21, 2015. (AP)

Each year the government sets a quota for how many animals can be killed. This year the number sits at 2047, across nine species; striped dolphins, bottlenose, pantropical spotted dolphins, Risso’s dolphins, pacific white-sided dolphins, short-finned pilot whales, false killer whales, rough-toothed dolphins and melon-headed whales.

Nine.com.au has received disturbing footage from the Dolphin Project, a not-for-profit organization on the ground in Taiji, that shows two striped dolphins being forcibly held underwater by two fishermen. The video was filmed a few weeks ago by Dolphin Project Cove Monitor, Heather Hill.

Fisherman forcibly hold the two dolphins underwater. (Dolphin Project/Supplied)

“They were in the middle of the slaughter,” Hill told nine.com.au .

“It is pretty horrific and heartbreaking. A lot of dolphins were under the tarp and there were a few floating out in the cove, almost motionless.

“It looked as though they were paralyzed with fear. A small vessel came up alongside two dolphins, two men grabbed each and held them belly up with their blow holes submerged.

“They then turned the vessel and disappeared underneath the trees, and the tarp. What their intentions were we can’t say, what happened underneath the tarp we can’t say.”

Dr Nahiid Stephens, a veterinary pathologist at Murdoch University, told nine.com.au this would be extremely distressing for the animals.

“Dolphins can hold their breath for a long period of time, they could well be under there for some minutes and still be conscious and aware that they are being prevented from getting to the surface – that would be incredibly stressful,” she said.

They then turned the vessel and disappeared underneath the trees, and the tarp. (Dolphin Project/Supplied)

Dolphins are also highly evolved social creatures, Dr Stephanie King, a behavioral scientist at the University of Western Australia, told nine.com.au .

As part of an ongoing study in Shark Bay , Dr King found that male bottlenose dolphins could remember individual vocal labels, or “names” to help recognise individuals in their social networks.

“It has also been shown that dolphins can remember these whistles for up to 20 years, so they have long-term social memories,” Dr King told nine.com.au .

“Dolphins have strong relationships with one another, and in that instance where they have animals dying, or animals under stress, individuals will be aware of what is going on.”

In 2017, juvenile dolphins being herded away from their family and into nets were filmed becoming so distressed they vomited and injured themselves thrashing in their constraints.

Dolphins captured in the cove are either sold into captivity, or slaughtered and sold for consumption. (Sea Shepherd/EPA)

The legal road set down upon by Action for Dolphins is a long one, but it is one that Ms Lucas is hopeful of.

“The next steps will be for the respondent, the governor of Wakayama, to file a response. The court will have to make a decision on the issue at standing; whether they think the plaintiffs are eligible to bring this case. That could go a number of ways; the court could require we have settlement, or more likely would require there’s a trial.

“Our goal is to get the permits cancelled which would mean the hunt couldn’t legally continue,” she said.

Nine.com.au reached out to Wakayama Prefecture Mayor Yoshinobu Nisaka's office but have not received a response.