The tender for the State Government's baited drum line strategy reveals sharks bigger than three metres will be shot and discarded offshore.

Earlier this month, the Government announced an aggressive policy in response to six fatal attacks in WA waters over the past two years.

The changes include setting baited drum lines and creating two monitored zones off WA, covering metropolitan beaches and large areas of the South West coast.

The tender request stipulates that any white shark, tiger shark or bull shark greater than three-metres in length, which is caught on the drum lines, will be "humanely destroyed".

The Opposition says the tender indicates the strategy is aimed at culling sharks.

The Government denies the measures amount to a cull, saying it is only targeting sharks that pose a threat to the public.

Labor's Dave Kelly says the tender indicates otherwise because it stipulates that lines will be baited at 6:00 pm.

"I don't think you can argue that baiting the drum lines before dark when the beaches will be empty, is anything other than a measure designed to reduce shark numbers," he said.

"Sharks who are swimming past the coast of Western Australia at two o'clock in the morning don't pose a threat to the public."

Mr Kelly says the tender does not suggest ways to minimise the risk to other species.

"I would have thought at a bare minimum the tender documents would require the successful commercial operator to take reasonable steps to prevent other marine species to be caught up in the drum lines," he said.

"That isn't anywhere in the tender documents that I can see."

Fisheries Minister Ken Baston says contracted vessels will monitor designated areas and apply baits to ensure constant protection during any 24 hour period.

He says the baits will be changed when required.

Commercial fishers have until January 3 to apply for the contract.

Open letter calls for cull to be abandoned

Yesterday, 100 scientists co-signed an open letter to the State Government calling on it to abandon the cull of sharks and adopt non-lethal measures to protect beach goers.

Shark biologist Ryan Kempster has told the ABC that scientists do not think it is good policy.

He says investment in research would be more effective than a shark cull.

"This is really a chance to bring together the scientific community and professionals who work with sharks to voice their concerns about the lethal control of sharks," he said.

"It really states that this is not an appropriate way of dealing with sharks and mitigating the risk of attack."

Mr Kempster says there a number of concerns with the policy.

"The drum lines alone are essentially indiscriminate; they will attract and kill any animal that bites at the hook, so this could be sharks, turtles, a number of different fish so you don't know what you're attracting," he said.

"Then also when you have dead animals hanging on the line this attracts in more so essentially you're attracting more animals to the area."