TORONTO -- Six weeks into the Canuck fall TV season -- which, like the U.S. tube, has seen total viewership dip -- CTV overwhelmingly dominates the ratings game with its slate of returning shows like "Grey's Anatomy" (Canada's top program), the final season of homegrown hit and top sitcom "Corner Gas" and surprise hit "So You Think You Can Dance Canada," the country's top new show.

But while CTV claims eight out of the 10 most-watched programs (all with average auds of more than 1.7 million) among total viewers and the 25-54 demo -- including "Grey's Anatomy," the "CSI" shows, "Desperate Housewives," "ER," "Amazing Race" and "Dancing With the Stars" -- the net splits the national 18-24 demo with Global, which carries "House," "Family Guy," "Heroes," "The Simpsons" and the latest installment of "Survivor."

Still, the real northern battleground is the second-tier networks: CTV's A, Global's E! and Rogers' CityTV, duking it out city by city for the younger demo with shows like "Knight Rider" (E!), "Fringe" (A) and "Chuck" (CityTV).

"I think traditional ratings don't match the number of people who see A shows like 'Gossip Girl,' and I know ratings companies are looking for ways to capture those viewers," says CTV president of creative, content and channels Susanne Boyce.

Both CTV and Canwest stream many of their shows post-broadcast. The increasingly fragmented TV dial and lingering effects of the U.S. writers strike are cited by both Boyce and Canwest VP of content Barbara Williams as reasons for the viewership dip this fall.

"There were fewer new shows available relative to past years, but as every quarter goes by, that will disappear," says Williams, looking to Global's midseason to increase its share of Top 10 performers. "There's excitement in our ship about '24,' which was impacted by the strike, 'Lost' and a twisted new show 'Dollhouse.'�"

CTV has its perpetual No. 1 show "Canadian Idol" rolling out midseason and isn't taking its long-standing No. 1 spot for granted. With aud faves "ER" and "Corner Gas" departing this season, a slate of homegrown dramas and sitcoms are in development.

"We are always looking at ratings shifting shows but not in a foolish way," Boyce says. "You have to show faith in some things. For instance, 'The Mentalist' didn't come out of the gate strong, but it's building every week. We have a 52-week schedule."