Jack, I was somewhat curious about the movie, so did some reading on Internet. Evidently they did some extensive testing at Labs, and he didn't get poisoned. Evidently just starved. They said there was some rope bridge less than Half a mile from the bus that they found his body in. In addition there is a Alaskan dude out there that brings people to the bus on a 4 runner. He stated in summer it is impossible to not catch salmon in the river. They are so plentiful you can literally flip them out of the river with a pine branch.
Last resort, wouldn't you start a huge fire before starving? People familiar with Alaska just think he was way over his head.:shrug: