Opponents of the Western Australian government's shark-killing program have responded angrily to the first slaughter in the state's waters.

The WA government has contracted a fisherman to set and monitor baited drumlines one kilometre off beaches in the south-west region.



The fisherman was reportedly seen off Old Dunsborough on Sunday morning shooting a large shark that had been caught in the lines and towing it further out to sea.



The lines were set up on Saturday afternoon.



American wildlife ecologist David Steen decried the policy, which was brought in after a seventh fatal shark attack in WA waters in three years, as a "shameful, archaic attempt to pre-emptively reduce conflict with people".



"So sad" and "shame", others wrote on social media.



Sea Shepherd's Jeff Hansen said the shark was "believed to be a beautiful tiger shark" more than three metres long.



"Can we expect [WA premier] Colin Barnett to be sporting one of those Mick Dundee hats but with shark's instead of croc teeth soon?" the WA opposition's Paul Papalia tweeted.



The controversial program went ahead after federal environment minister Greg Hunt granted Western Australia an exemption under the Environment Protection and Biodiversity Conservation Act, allowing the protected great white shark to be killed.



In a notice to mariners warning of navigational hazards, the WA government said drumlines would soon be deployed in metropolitan waters, extending from Quinns Rock Beach to Warnbro beach.



It has been forced to rope in its own department of fisheries officers to do the work after commercial operators pulled out following threats from activists.



The lines, which are attached to floating buoys, bear the warning: "No vessel is to approach, moor to or interfere with the above equipment at any time – modified penalties will apply."



Activists have pledged to interfere with the program.



A rally against the cull is scheduled for Cottesloe beach – the electorate and home suburb of Barnett – on 1 February.



Thousands of people attended the previous protest.

