SD, coho and silver are the same fish as is king and chinook. Copper River? Boo. That's pure marketing. Not once have I ever met any Alaskan or lower 48er that could tell the difference between Copper, Kenai, Nushagak, Kvichak, or any other Alaskan river king, silver, or sockeye.
As far as caviar or what we'd call ikura, the best is made from fresh chum/dog salmon. Fantastic stuff when made fresh, the eggs literally pop with flavor and not fishy or salty at all. We'd toss the stuff into scrambled eggs or mix with mayo, minced shallot and capers and use it as a spread. Once you taste it all you can think about is getting a bigger spoon to shovel the stuff in.
The health benefits for eating salmon either wild or farmed are literally off the charts. I even keep a stash of cheap canned salmon around at all times. If I were limited to but one source of protein, salmon would be it. To me its the most versatile of all culinary flesh that swims, crawls, fly's, or walks. Ain't no nooky, like chinooky!
