Biology Reference
In-Depth Information
swimming fish within three months. By fall, these herring have left the
bay, not to return until they are mature and ready to spawn at two to three
years old.
In recent decades, juvenile herring in San Francisco Bay have suffered
from loss of food, predation, and changing conditions. State fish managers
estimated that the spawning biomass for the 2009-2010 season was 38,409
tons—down from an historical average of more than 49,000 tons but up
from the 2008-2009 low of 4,833 tons. Though herring support one of the
bay's handful of remaining commercial fisheries, the fishery's future re-
mains uncertain (see p. 173, “Last of the Fishing”).
Northern Anchovy
he Northern Anchovy (
Engraulis mordax
), the most abundant fish in the
bay, is a small silver fish about the size of a french fry. As the foundation of
a second commercial bay fishery, anchovies are used mostly as live bait for
party boat fishing vessels and private anglers.
Northern Anchovies are easily distin-
guished from other small silver fish by
their severe overbite—a characteristic
scientists call “stupid mouth.”
(Aquarium of the Bay)
The life cycles of Northern Anchovy and herring are reversed. Whereas
herring live offshore and come into the bay to spawn, most anchovies
spawn offshore and move into the bay to grow up. Though this species can
be found inside the bay for much of the year, their numbers peak from
April to October. Scientists think that coastal upwelling and the subse-
quent plankton blooms trigger their spring arrival, and cooling bay waters
spur their fall departure. Northern Anchovy can live for up to four years.
Longfin Smelt
At first glance, the Longfin Smelt is just one more of the half-dozen small
silver fish species found in the bay. But the Longfin Smelt (
Spirinchus tha-
leichthys
) makes more complete use of the bay than any other small native
fish. Its ability to tolerate a particularly wide range of salinities allows the
Longfin Smelt to linger in the estuary's changeable water conditions.
Within a month of hatching, their tiny larvae (roughly 0.4 inches in size),
