 Atherinops californiensis
 Distribution of jacksmelt in San
Francisco Bay
Jacksmelt range from northern Oregon to southern Baja California. They are a
surface-oriented pelagic species common along the coast and in bays and estuaries.
Jacksmelt are not commercially important, but are a major component of the recreational
fishery from piers and jetties.
During late winter and early spring, jacksmelt immigrate from the nearshore
coastal area to the Bay to spawn. Eggs are demersal and adhesive. Large schools of
juveniles remain in the Bay through the summer, emigrating to coastal waters in the
fall. Juvenile jacksmelt average 110 mm at the end of their first year and 180 to
190 mm after two years, when they become sexually mature. They reach a maximum
length of approximately 350 mm, and live nine to 10 years. Jacksmelt are omnivores,
primarily feeding upon algae, crustaceans, and detritus. They are preyed on by
piscivorous fishes, including striped bass.
Jacksmelt young-of-the-year (YOY) abundance indices have been very low since 1988,
with lowest index in 1993. We have no hypotheses as to what factors may be controlling
jacksmelt abundance in the Bay. Annual abundance indices for
YOY jacksmelt are generated from the San Francisco Bay
Monitoring Program using midwater trawl data.
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