Snake river Cutthroat Trout

It's a self-explaning species...as you can tell the red-orange marking on the throat... the cutthroat trout. What a beautiful trout species... not only the brillient red marking stikes me, but also the redish - translucent fin are extremely attractive. To my knowledge no one has study the read marking to the cutthoat trout, what is the function? what is the pigment? I have no clue. Maybe I should plan a long vacation in the smoky mountain region and observe this species more closely : )