Two tiger sharks have been caught on baited hooks set by the Fisheries Department off metropolitan beaches this morning.
The first is thought to have been about 1.5m to 2m long.
It was pulled aboard the Fisheries vessel, the hook was removed and it was returned to the water.
The State Government policy stipulates that only great white, tiger and bull sharks greater than 3m can be killed if caught by the drum lines.
An under-sized tiger shark, was caught soon after and released.
Channel 7 reporter Geof Parry told 6PR Fisheries officers struggled to get control of the shark as it thrashed in the water.
The release prompted a warning on Twitter from Surf Lifesaving WA.
"Swimmers at Cottesloe have been advised to exercise caution. A 2.6m Tiger shark has been released 1km from shore by Dept Fisheries," it said.
The Fisheries Department set the baited hooks early this morning 1km out to sea off popular Perth beaches.
Up to 36 drum lines will be set off Perth beaches. The first drum line was set off Leighton beach.
Federal Greens leader Christine Milne said the policy was becoming an embarrassment that would have political and environment implications for the State.
Senator Milne, who will address an opposition rally at Cottesloe tomorrow, said the policy was proof of a Liberal antipathy towards conservation.
"You have the premier of Western Australia in cahoots with the Abbott government now going out and trying to destroy great white sharks," Ms Milne said.
"It is wrong to institute this cruel policy, which will have by-catch as well."
Earlier, Sir Richard Branson said the policy would backfire, driving away tourism rather than boosting it.
The Fisheries Department was given the job of setting and monitoring the lines off Perth beaches after private contractors who tendered to do the work received threats.
But Fisheries officers have expressed concern that they will be targeted by opponents of the State Government's shark-kill policy.
Fisheries officers are unhappy, and their union says they are on a collision course with protesters.
"Our members have the right to go to work and perform their duties in a safe manner but that could be compromised with their own employer's decision this week," the Community and Public Sector Union/Civil Service Association said.
The private contractor in charge of the drum lines in the South West has a hotline to police in case activists try to sabotage his boat or equipment.