Science & Technology

Can Technology Replace Shark Nets

If there was a shark in the water at your local beach, would you want to know about it before you dived in?

Would you change your mind about swimming if it was a one-metre hammerhead? What about a five-metre great white?

A Senate committee report handed down this week has concluded shark nets are ineffective in stopping shark attacks and may lead beachgoers into a false sense of security.

“[Nets] range from only 150 to 180 metres in width [and] sharks can swim around and under the nets,” the report states.

Instead, the committee has pointed to emerging technologies being used in conjunction with shark alert apps as the future frontline in shark management.

Victims unaware sharks had been sighted prior to attacks

After the fatal shark attacks on Damian Johnsonin Tasmania and Tadashi Nakahara in Ballina in 2015, former professional surfer Sarah Beardmore began questioning why the location of sharks wasn’t better communicated to the public.

“In both incidents there were similar sharks that had been seen in the area in the previous 24 hours,” Sarah said.

Sarah and Allan Bennetto decided to create an app to provide a centralised platform for people to report shark sightings, and to check for the presence of sharks at their local beaches.

“And then it just kind of grew and got bigger and bigger,” Sarah said.

Today the Dorsal app is easily the most widely used shark tracker in Australia with about 250,000 users.

The app’s interface shows shark fins dotted on a map to indicate the up-to-the-minute locations of sightings at beaches and rivers around the coastline.

And Sarah says she’s confident people are using it to decide where to swim.

“We had a few people get in touch with us and thank us for that report because they changed locations of the beach they were going to that day.”

Not all states keep track of sharks

But there are noticeable gaps in shark tracking.

On the app’s map of the New South Wales and Western Australian coasts, dense clusters of shark fins show the location of potentially dangerous sharks that have been caught, tagged with a satellite tracker, then released.

When the sharks swim in range of a receiver tower, their location is recorded and communicated via official Twitter and Facebook channels, which is then relayed to the app’s users.

But in Queensland for instance, there are only a few scattered fins marking the spots where members of the public have submitted shark sightings.

Unlike New South Wales and Western Australia, there is currently no shark tagging program for sharks caught in Queensland.

“The Department of Agriculture and Fisheries does not release dangerous sharks caught in the Queensland Shark Control Program,” a Fisheries Queensland spokesperson said via email.

In Victoria as well, there is only very limited publicly available shark tracking data.

Essentially when tagged sharks leave the New South Wales border, they disappear from the radar.

Do we really want to know?

The peppering of shark fins across the tracking map betrays a reality that many would rather not think about — sharks are in abundance at our beaches.

But given the relative scarcity of attacks, does an app that alerts us to their presence do more harm than good?

Surfer Daniel Webber, who made submissions as a private citizen to the Senate committee, was asked whether he used the New South Wales DPI’s SharkSmart tracking program.

“The worst thing that happens is when the surf backs off, you are dangling for 20 minutes and you start to think about [sharks]. Usually for me that is a downward spiral and within half an hour I get out.”

Sarah agrees a shark tracking app is not for everyone.

“We do get a lot of surfers who say they’d rather not know,” she says.

“But it is like anything, you can either use the app or you don’t. It’s like any single app out there.”

Drones, AI not enough to change netting policy

The trials have involved training artificial intelligence software attached to drones to distinguish sharks from dolphins and other marine life, and to estimate size.

The trials have proven successful, and the technology is going to be used by some lifesavers this summer, according to the director of drone company Hover UAV, Jackie Dujmovic.

“It works,” she says.

“The AI is ready to go and it won’t take much for me to train up [operators].”

And Jackie has begun working with Sarah’s team to streamline the information that is fed to the app, in order to give users more precise data about the shark threat at their local beaches.

While flying drones during the trials, Jackie says she saw things that would surprise the average beachgoer.

“We see probably a lot more sharks inside those nets,” Jackie says.

“Virtually every time I fly [a drone] I see a shark. I do see them near people a lot. But they’re not always of hazardous nature.”

Although the ecological argument against nets is strong — dolphins, whales, dugong, turtles, and manta rays feature heavily in annual “non-target species” reports — their efficacy as a shark deterrent is still being debated.

Despite the rapid advance in non-lethal technologies, the idea that nets provide a physical barrier between swimmers and sharks will be difficult for opposition groups to dismantle.

In response to the Senate committee recommendation to phase out nets in Queensland, the Palaszczuk Government released a statement saying doing so, “will place lives at risk”.

“85 of Queensland’s most popular beaches are protected by nets or drumlines in a program that has been supported by successive governments since 1962,” the statement reads.