I've seen people eat chinooks in some pretty advanced states of coloration. However, I think the brighter the better should be the rule. The coloration of a salmon's flesh depends on his diet; The red coloration comes from the carotene in the euphausids and shrimp that the salmon have been dining on. Not knowing a lot about Great lakes salmon, I would assume that most would lack the bright red color typical of many, but not all, of our coastal fish. There are some races of coastal chinook (white kings)that seem to lack this color entirely. There was a discussion on this site a while back on the subject of these fish with a good deal of disagreement on whether they were better/same as/worse flavored than their more conventionally colored cousins.