The sexes are separate but have similar external appearance. The gonads are the prominent, crescent-shaped end of the internal organs. Ovaries are dark green and testes can be cream, light brown, light green or pinkish in color. Abalone release eggs or sperm through the open holes in their shells. For effective fertilization, abalone need to be within a meter of each other. When abalone are too far apart, their eggs do not become fertilized. Fertilized eggs develop into larvae which can be carried by currents for about a week. The larvae settle to the bottom and develop into very small versions of adults.

Most male red abalone start to reproduce when they are 4 inches in length and 5 years in age. Most females are reproducing at 5 inches in length and 6 years of age. Small females produce far fewer eggs than larger females; a 5 inch female produces about 300,000 eggs while females larger than 7 inches produce about 2,500,000 eggs. Although abalone produce large numbers of eggs and sperm, reproductive success is very sporadic. The last major successful reproductive period for northern California red abalone was probably in the late 1980s.