I find it unusual that a Party (as per Antony Greens page) don't field candidates. That seems to be common place in Australia and i think the UK (?). The Port Adelaide and Ramsay SA by-elections will also not have Liberal candidates.
Why is this the norm down under? Here its unheard of for parties not to field candidates... even in ridings considered un-winnable (i.e the tories will no doubt run in Toronto-Danforth, even thougth they will never win)
The PLQ didn't field a candidate against Marois in the 2007 Charlevoix by-election, and that's usually been the case for such affairs in Quebec.