An article in The Hollywood Reporter indicates that some of the most popular anime series in Japan including One Piece, Sgt. Frog and Bobobobo-Bobo have all had their time slots changed because of ratings drops.  Previously shown during the 5pm to 8pm period on weeknights, all three series were shifted to weekend morning slots.  According to The Reporter lower viewing by Japanese school kids was the reason for the changes. 

Like American kids, Japanese schoolchildren have a bewildering number of after school activities including sports and music lessons plus levels of cram school tutoring that are unmatched in this country.  Add in a serious penchant  for video games (a recent survey of Japanese fifth graders found that 92% owned video games), plus the addictive qualities of Nintendo's superhot Wii system, which totally dominates the Japanese market, and there is another potential reason for the decline in anime viewing.

Although anime TV series no longer command the 30+ share of TV viewers they did in the 1970s and 80s and both anime and manga sell-through numbers are down (see 'Japanese Anime, Manga Markets Decline'), there is no reason for American anime fans to despair.  Buoyed by international sales the Japanese are creating anime series at a ferocious rate and top anime movies franchises such as Pokemon, Detective Conan, Doraemon, and Crayon Shin-Chan still do very well at the box office, while Hayao Miyazaki's films are in a class by themselves, easily besting any Japanese live action films in box office take.