This Sockeye Salmon (Oncorhynchus nerka) displays a spawning kype (photo credit: Ron Harris).
Not to be confused with the popular internet phone/video chat platform of a similar name, kypes are hook like structure that develops on the jaw of some male salmonids during the spawning season. Though Skype for salmon is still far fetched, this secondary sex characteristic does, in fact, have a role in communicating sexual fitness.
Research suggests that kype size has been linked to spawning frequency, via mate choice (that is, female salmon find a hooked jaw desirable) and competition on spawning grounds (namely, battles between males where the winner gets to pass on his genes). For repeat spawners with an iteroparous reproductive strategy, the elongated jaw is reabsorbed after the spawning season ends.