Ashton Kutcher's decision to end his very successful MTV series "Punk'd" could leave the network hurting on Sunday nights. 
   “Punk’d” became the 9 p.m. anchor for MTV’s “Sunday Stew,” a new two-hour block of programming targeting teen boys that debuted this fall. The future of the programming block looks grim with Kutcher's sudden decision last week not return for another season, even though MTV had already renewed the second-year show.
  "Punk'd" has been MTV's highest-rated show among young people since the "Newlyweds" finale. It routinely leads the 90 minutes of programming after it to competitive ratings; without "Punk'd" to anchor the slot, MTV could lose a lot of viewership.
   It’s possible that the male-targeted programs can continue to draw viewers without the night’s anchor. But it's also quite possible that MTV could decide to reschedule the programs and dissolve the “Sunday Stew” franchise altogether.
   Last week the show drew a 2.9 rating among 12-34s, and MTV maintained most of its 9 p.m. audience for 9:30 entry “Viva la Bam,” with a 2.6 rating. “Punk’d” was second only to Spike’s WWE wrestling among 12-34s on cable last week.
 The show is a younger and updated version of the classic “Candid Camera,” only the subjects of the elaborate pranks are always popular celebrities.
   Some speculate that Kutcher bowed out of the show before too many celebrities caught on to the scheme and ruined the gag. The series successfully “punk’d” people like Katie Holmes, Blink 182’s Travis Barker, Nick Lachey and Pauly Shore.
   In November “Punk’d” was month's No. 1 cable show among 12-24s with a 4.7 rating and drew a 5.0 among teens. Last week, the show drew a 3.1 and a 3.9 rating respectively.
  The decline may be a one-time drop because of the CBS finale of “Survivor: Pearl Islands” that night, which performed well among teens in the same time slot.
   "Survivor" ate into almost all audiences on Sunday night, but it was definitely noticeable on MTV, where the four half-hour programs were off from their highest-rated episodes in November and all posted declines from the previous week.
  “Wildboyz,” the 10 p.m. entry, lost 34 percent of its 12-24 audience, finishing in fifth place for the week with a 2.7 rating, down from last week’s 4.1 rating.
  Similarly, “Viva la Bam” bettered “Punk’d” among 12-24s and teens last week, but was still off from its previous week’s ratings, down 23 percent to a 3.4 among 12-24s and 12 percent to a 4.6 among teens.
   Note: The younger viewers charts will be posted when they are released later today.