The World Surf League has deployed dedicated shark monitoring jet skis to oversee competitors at the Margaret River Pro the day after several surfers were scared out of the water on the eve of the event.

Water photography is also off limits at this year's event with photographers also required to film and shoot from jet skis as a further safety measure.

US surfer Kanoa Igarashi described the size of the shark seen at Margaret River on Thursday at sunset as "like a submarine".

"We are looking out and see this fin emerging out of the water, it looked like a submarine, it kept growing," Igarashi told Stab Magazine.

Mick Fanning is rescued by a jetski after a shark attack at Jeffrey's Bay in 2015. ( ABC News )

"Then it was flustering and thrashing. I looked over and I'm like 'wow, there's a dolphin next to the shark' but it was actually the tail fin. It was seven or eight feet away from the main fin."

WSL had announced it would beef up shark monitoring procedures following Mick Fanning's close call with a large white pointer at Jeffreys Bay, South Africa in July last year.

The two skis, each fitted with sonar tracking devices, monitors and lights, will patrol the open ocean break of Surfer's Point and back up venues of The Box and North Point should conditions permit.

New measures "welcome addition"

WSL Surfer's Representative Adrian Buchan, one of the first to console Fanning upon his return to shore in South Africa, said the addition of the skis would be a welcome addition.

"It was definitely a very pretty confronting experience, not only for Mick but for all of us that were there to witness," Buchan said.

Adrian Buchan, left, was one of the first to comfort Mick Fanning (in blue) after the shark attack in South Africa last year. ( WSL: Kirstin Scholtz )

"The possibility of something like that happening is obviously something we are all aware can happen, but you do try to put it in the back of your mind as much as possible."

Buchan said the WSL was quick to assure all competitors it would invest in increased surveillance at Margaret River and Jefferys Bay.

The WSL's VP of communications, Dave Prodan said the drivers of each ski would also be in communication with personnel on land.

"For this event (Margaret River) the WSL has partnered with Surfing WA and Balconi (Perth based communications company) to develop a new prototype technology for underwater surveillance," Mr Prodan said.

"While this is still in the testing phase, the WSL will see if the technology can augment pre-existing measures in place."

J Bay protocols worked to ''great effect"

Mr Prodan said protocols put in place for last year's Jeffreys Bay event had worked "to great effect" but the WSL "realised we were still very fortunate that no one was harmed. Following the incident and ongoing discussion with out athletes, we've heightened our focus here for the 2016 season."

One of the dedicated jet skis (left) used during competition at Margaret River today ( Supplied: WSL/Cestari )

He also said the decision for photographers to work on the back of jet skis was part of the "athlete/staff safety enhancements for Margaret River."

Buchan said while the additional measures would add "peace of mind," all competitors understood the risks of surfing in the open ocean.

"Thinking back to the incident with Mick, if a shark that size wants to have a go at you, there's really nothing that can be done to prevent it entirely," Buchan said.

"It is simply one of the risks of our sport and we all understand that."

Competitors were greeted with clean headhigh waves for the first day of competition, with Julian Wilson the highest heat scorer for the men's with a 17.10.

US surfer and reigning world champion Carissa Moore posting the highest for the women's with a combined total of 15.77 in her heat against Sydney's Laura Enever and Sage Erickson.