Endangered Species Act 5-year Status Review of Black Abalone (Haliotis cracherodii)

Black abalone are marine snails, with one shell and one large muscular foot used for locomotion
and adhering to rocky substrates. They are relatively long-lived (estimated to live up to 30
years), have separate sexes, and are “broadcast” spawners, meaning that both sexes shed their
gametes into the sea and fertilization is entirely external. Successful reproduction is dependent
on spatial and temporal synchrony among spawning individuals; that is, males and females in
close proximity to one another (within meters) and spawning simultaneously have a higher
likelihood of reproductive success. An experimental simulation of black abalone spawning
employed release of inert neutrally-buoyant particles in two size categories similar in size to eggs
and sperm in black abalone habitat at San Nicolas Island in southern California (Blaud 2013).
Data were consistent with the premise that probability of fertilization may increase if spawning
males and females are within four to five meters of one another.