And I used to be such a tuna guy. Wait, I still am.
There's something more appealing to me about the color, texture, consistency of maguro (tuna) sashimi than the salmon variety. The best tuna and salmon sashimi melt in your mouth, releasing unique flavors ably complemented by the right amount of wasabi and soy sauce. The difference is that--
a) Salmon doesn't have tuna's somewhat iron-bloody aftertaste (the taste of salmon sashimi can be described as somewhat sweet, creamy); and
b) Salmon melts in the mouth better
Given a choice, I'd always go for tuna, even if only for reasons of price and availability. Tuna can pretty much be found swimming our oceans without making a salmon's trips to fresh water streams for purposes of spawning. And cheap tuna can be just that-- cheap. Salmon is more prized, therefore harder to find or get to, and therefore more expensive.
But you're asking Why am I Salmon? Reasons exist beyond a pun on the movie I am Sam (good movie starring Sean Penn, do check it out. Incidentally the pun was also a conscious choice).
As I'm a creature of metaphor, nuance, meme and pop culture references, you can be sure that this post is not simply about fish.
A salmon's life is apparently more complex than his tuna counterpart: he's born in a fresh water river or stream, migrates to a big ocean and then feels an irresistible desire to return to the stream of his birth.
I am Sam. And I am Salmon.