Western Australia’s controversial policy to catch and kill large sharks could result in the risk of shark attacks on people actually increasing, local scuba divers have warned.

WA government contractors are to deploy 72 baited drum lines 1km off popular beaches in Perth and the south west of the state on Friday following a rapid tender process that closed on the weekend.

The government’s strategy aims to draw sharks to the baited hooks, where they are trapped and die or are dispatched by roving hit squads in boats, which will shoot sharks over 3m long.

The measure is in response to a clutch of recent fatal shark attacks off the WA coast, although it has proved highly controversial. More than 4,000 people gathered on a Perth beach on Saturday to protest against the cull, which opponents claim is cruel and unnecessary.

Scuba divers who spoke to Guardian Australia said the policy would also heighten the danger to humans, rather than decrease it, by encouraging sharks closer to shore in search of the bait.

Natalie Banks, who has dived near Rottnest Island for the past eight years, said the baited lines would cause her concern for her own safety.

“Before, there was no fear because the statistics on shark attacks are so low, but now there is bait there, it’s very worrying,” she said. “A lot of scuba divers feel that sharks will be attracted to the bait lines and there will be more shark attacks as a result, on people who are diving, swimming or surfing.

“By doing this, we’re basically introducing sharks to where humans are conducting recreational activities. I will certainly be investing in a shark shield [a sonar device to ward off the animals] when I go into the water.”

Banks, one of the organisers of the cull protest on Saturday, said she had heard from divers on the east coast and overseas who had cancelled plans to visit WA as a result of the drum line strategy.

Chris Dodd, head instructor at Diving Frontiers, told Guardian Australia that he had never seen a great white shark in nearly a decade of diving in the Perth region.

“With all the drum lines going in, people are wondering for the first time whether it will be dangerous,” he said. “We take our open water students 400m offshore and for the first time it will cross my mind that sharks will be there.

“I can’t believe in today’s society that [WA premier] Colin Barnett can have such a kneejerk reaction. We aren’t cavemen who kill things because we don’t understand them. A cull is definitely not the answer. We need more education and for people to treat the ocean like the wilderness it is.”

Lee Johnson, managing director of Perth Scuba, WA’s largest diving store, said divers were not avoiding the water due to fears over sharks, but that could change.

“It’s a bit like the start of the crayfish season when there are cray pots everywhere and the sharks get excited,” he said. “I haven’t heard anyone say they are fearing for their lives, but that could certainly change once they start baiting.”

The WA government has insisted it will stand by its cull, leading the state’s Greens party to explore whether to take legal action to stop it. The community group West Australians for Shark Conservation has pledged to sabotage drum lines if they are installed, while some shark fishermen have raised concerns that the lines may unintentionally catch harmless species of shark, harming their businesses.

Kim Haines, the acting WA premier, said the policy had been devised following consultation with experts from the federal government and several universities.

“The drum line and netting practices in New South Wales, Queensland and Natal [South Africa] have been taken into account and adapted for Western Australia,” he said.

“Queensland has over 300 drum lines and nets, and since this program began in 1962, there has been only one shark-related fatality. We do not wish to use nets because of the dangers of catching other marine life.

“There is research to say that sharks are only attracted to the smell of baited hooks from a few hundred metres away.

“As such, the shark must already be in the general area to be attracted to the baited hook. The hook is of a size and design to only catch larger sharks.”