I like playing a little game when I fish in the early season. I try to guess the gender of trout. You can’t keep the trout so there is nothing to prove your guesses.
Male trout are typically more colorful than female trout and the male trout’s head is more pointed and elongated. Female have more rounded heads and the distance between the eye and the point of the upper jaw is shorter for females.
Male trout are more colorful because of the need to attract a mate. The females are more muted to hide themselves from predators because they carry the eggs.
Male trout develop a hooked lower jaw when they are mature. This hooked lower jaw is called a kype. The kype becomes even more profound during spawning times. The colors of the males are more flamboyant during spawning also.
There are four kinds of trout in our waterways here in southern Wisconsin. I will demonstrate each species and say whether it is a male or a female. The four types of trout are the extremely rare tiger trout, the native species the brook trout, the European transplant the brown trout and then there are rainbows in our waters that are released brood stock from the hatchery.