Mature Yellow perch can be easily sexed just prior to spawning by the distended abdomen of the female that is full of eggs, and the lack of a distended abdomen of the male. Milt also is easily exuded by the male with slight hand pressure toward the urogenital orifice.
As you can in the following photo the male is smaller and lacks the distended abdomen of the female fish. These fish are the same age. Female yellow perch grow faster and larger than males.
Closer to spawning time the females become very grossly distended as in the following photo. Very hard to confuse this with a male!
