Dolphins being herded away from their family and into hunters' nets have been filmed becoming so distressed they vomit and injure themselves thrashing against their restraints.

Animal welfare advocate Liz Carter, from Melbourne, captured confronting footage of wetsuit-clad divers separating juvenile dolphins from their pods and trapping them in a cove at Taiji, Japan, in late January.

The Australian volunteer travelled to the dolphin-hunting town with Blue Cove Days to film the horrifying selection process hundreds of animals go through as they are taken from their families to be drugged and trained to perform in marine parks across the globe.

She said this group were separated from a pod of at least 200 dolphins and herded into the shallows where they frantically tried to escape.

Liz Carter, from Melbourne, captured confronting footage of wetsuit-clad divers separating juvenile dolphins from their pods and trapping them in a cove at Taiji, Japan, in late January.

Divers pounce on the dolphins, pushing them underwater where the wild marine creatures struggle to breathe.

"The pod was panicked and they knew they had been separated from their family," she told the Daily Mail .

"In one image of a dolphin you can see it vomiting, and to me this looks like his/her own intestines."

"This was not the only dolphin captured to be vomiting from the stress endured over five days."

The dolphins have never encountered netting in the wild and have no idea how to jump to safety.

She said the dolphins have never encountered netting in the wild and have no idea how to jump to safety.

One can be seen almost escaping but is snagged inches from freedom and dragged back into the confines of the net by three divers in snorkels.

Ms Carter said the dolphins are starved, fed fish laced with sedatives and then crammed into sea pens where their "spirits are broken" before being transferred and "exploited for entertainment".