WA voters stay away from polls

West Australian voters are showing a strong lack of interest in two federal by-elections.

The most recent Australian Electoral Commission figures, from the first eight days of early voting, show 12,800 ballots have been cast in the Queensland seat of Longman.

In the South Australian seat of Mayo, 7873 pre-poll votes have been recorded with 3450 cast in Tasmania's Braddon.

However, in Perth the figure was 2754 and in Fremantle 2397 votes have been cast.

Professor of politics at University of Western Australia, Peter Van Onselen, said by-elections traditionally had lower voter turnout than general elections.

However, there were other factors at play in WA.

"The Liberals not running (in Perth and Fremantle) may well lead some conservative voters not to turn up, or at least not be energised enough to turn up to pre-polling," he told AAP.

He said he didn't expect the lower-than-usual turnout to impact on the July 28 by-election results in WA.

"The Greens won't win Fremantle, and Perth is a 'lay down' (misere) for the Labor Party," he said.