Update: The fisherman contracted to set and monitor drum lines in the South West has caught and killed a large shark this morning.
The shark was caught off Meelup beach, the scene of the first catch and kill under the State Government policy.
Channel 7 reporter Rob Scott, who was on a boat following the fisherman, said the shark thrashed and rolled in the water after the first shot was fired into its head.
At least one more shot was fired, he said.
Scott said the sight of the shark being killed was distressing.
He said the fisherman used his boat to try to shield the view of the shark being killed.
The carcass was taken further out to sea and dumped.
Marine Rescue Unit campaign co-ordinator Simon Petterfy has had his boat impounded by police today.
Mr Petterfy, an animal activist who made international headlines in 2012 when he boarded a Japanese whaling vessel, was preparing to take footage of the latest shark killing when he was given a “move on” notice.
Mr Petterfy told Fairfax radio that police said his boat trailer was unregistered.
He was also found to have thumblocks with him, which were often used by protesters to secure themselves to objects.
The number of sharks caught and killed under the drum-line policy in the South West and along metropolitan beaches is unclear.
Sea Shepherd released pictures yesterday it said was of a shark caught in the South West drum lines.