I think its temp. related, I've seen the same thing in past warm water years (even worse during El Nino years) I don't know about Sitka but the area I'm fishing is just now starting to take off (easy silver limits) which is 2 to 3 weeks later then normal.

FJ15, Ocean silver fishing generally starts earlier then the inside (such as Ketchikan) areas, early to mid July is normally very good silver fishing here where as things don't really get going inside till early to mid August on the inside waters, silver fishing also ends earlier on the outside with most silver fishing done by early Sept. while its prime time inside.