Tasmanian surfer Brooke Mason lived through her worst nightmare last week when Tadashi Nakahara was fatally attacked by a shark near Ballina in New South Wales.

Ms Mason was no more than 15 metres from the 41-year-old Japanese surfer when the shark attack occurred.

A popular identity in the Tasmanian surfing community, 19-year-old Ms Mason was only two days into a year-long break from studying medicine at UTAS.

Brooke Mason had been speaking with Tadashi Nakahara just minutes before he was fatally attacked by a shark off the NSW coast at Ballina. ( Supplied: Facebook )

The attack and ensuing rescue attempt have left her deeply shocked and the incident is testing both her resolve to live a surfing lifestyle and the desire to help people through medicine.

Ms Mason had been chatting and laughing with Mr Nakahara, who had been in Ballina for a year, right up until a few moments before the attack.

"We were just talking about how good the waves were and how beautiful the area was and how alive it was," Ms Mason said.

"I saw him get a great wave, a three-second barrel, and I hooted and hollered for him."

Ms Mason was sitting just 10 or 15 metres from Mr Nakahara when she saw him move suddenly out of the corner of her eye.

"I saw him take a huge breath and go under and I thought he was just, like, going for a swim," she said.

"But then, right after he was pulled under there was blood everywhere; there was blood near me – it spread out in the water so fast.

"My brain was saying 'that's a shark attack'. My legs were quivering and I looked away and looked back and there was just blood, but he wasn't there."

A huge amount of blood had spread across the wave-catching zone and neither Mr Nakahara nor his board had surfaced.

Ms Mason and the other surfers in the water knew they had witnessed an almost certainly fatal shark attack and a quiet but immediate panic set in.

"My fight or flight response took over and I started paddling in. Everyone was paddling in, not even yelling at first, just so strangely quiet," Ms Mason said.

"My mind had gone into a kind of war-zone mode. It felt like everyone would be attacked.

"The whole attack was so quiet; I just watched, he was just dragged straight under."

A couple of the surfers got to Mr Nakahara's badly mauled body and were struggling to get it ashore.

Moments after her panic had peaked, Ms Mason found herself turning back to the danger zone, wanting to help.

"It's weird because you want to be so brave, but at the same time you want to stay alive. Even later on the land, I was still afraid of the shark," she said.

Brooke Mason and her friend Leo Plaza at Wellington Falls near Hobart last month. ( Supplied: Leo Plaza )

"But it just broke my heart to see the bravery of those guys who carried him in.

"The big guy paddling next to me on the reef went to them to help and I took the boards in."

On the beach, Ms Mason said her medical training helped her to deal with the grim state of Mr Nakahara, who had lost both legs.

She and others took leg-ropes off surfboards and used them as tourniquets. She cradled Mr Nakahara's head and attempted to comfort him by speaking to him.

Others administered what first aid they could ahead of paramedics arriving, but Mr Nakahara died on the beach from massive blood loss.

Ms Mason flew home to Hobart at the weekend to be with her parents, Nicola and Carl Mason.

Naturally they were concerned about their daughter heading back to northern NSW and braving the surf again.

"Everybody was a bit freaked out that I was pretty much next in line [for a shark attack], but it hadn't been me," Ms Mason said.

"I'm back at Byron now and I really want to get in the water. I'm trying to tell myself that I'll be alright, but I'm not sure. It's definitely going to be hard to not think about it."

The shark that attacked Mr Nakahara was believed to be a four-metre great white and there have been further sightings of large sharks close to the same beaches in the week since the attack.

Brooke Mason enjoying the freedom of the surfing life on the west coast of Tasmania. ( Supplied: Oscar Wyatt )

Ms Mason is of the opinion that over-fishing may be causing increased numbers of shark attacks on the Australian coast.

Despite her nightmarish experience, Ms Mason does not believe any kind of culling of sharks is the answer.

"I really reckon that it's our fault and if we can change something in our lives then that's what will make it a safer place," she said.

A couple of hours after speaking with ABC Northern Tasmania about her experience, Ms Mason paddled out amongst a large crowd of surfers at The Pass in Byron Bay, exactly a week since the attack at Ballina.

She said after some initial waves of fear when duck-diving and when seeing surfers fall from their boards, she found the experience enjoyable.

"A few nice waves came right to me and it felt kind of like Tadashi had sent them," she said.

"He would want us to keep surfing."