I'm having trouble with the notion that an apex predator like Orcas would be so forage specific - chinook - as to forego other available forage to the point of becoming ill, unfit, or even starving. It isn't like they're a species of finch on the Gallapogos (sp), with a beak sized and shaped for one specific kind of seed, making them ineffecient or unable to forage on other seed types. An Orca can eat any damn thing it wants, and if chinook are in short supply, exactly what physiological or behavioral limit is preventing it from grabbing a sockeye, pink, chum, hake, or a seal? Yeah, I read about the learned behavior, but that doesn't make the animal incapable of learning an alternate behavior. Something about this hypothesis isn't adding up.

Sg