Surf Smelt - Biology

Name: Surf smelt,Hypomesus pretiosus

Geographic Range: Long Beach, California to Chignik Lagoon, Alaska. An
Asian subspecies, Hypomesus pretiosus japonicus, is common in the
western Pacific. Surf smelt occur throughout the marine waters of Washington,
from the Columbia River to the Canadian border and southernmost Puget Sound.
They are an abundant schooling forage fish living in the near shore community of
Puget Sound. Although their movements within the sound are unknown, a number of
genetically distinct stocks are thought to occur.

Related Species: Surf smelt and salmon are members of the same
taxonomic order, Salmoniformes. Other common local smelt are the eulachon or Columbia
River smelt, (Thaleichthys pacificus) and hooligan or longfin smelt
(Spirinchus thaleichthys). Both are anadromous, running up rivers to
spawn in freshwater. Surf smelt can be distinguished from other forage fish such
as herring, sand
lance and anchovy,
by the presence of an adipose fin.

Life History: Surf smelt deposit adhesive, semitransparent eggs on
beaches which have a specific mixture of coarse sand and pea gravel. Inside
Puget Sound, surf smelt spawning is thought to be associated with freshwater
seepage, where the water keeps the spawning gravel moist. Eggs are deposited
near the water's edge in water a few inches deep, around the time of the high
water slack.

Observations of surf smelt spawning activity describe a highly adapted and
ritualized behavior. Several males will align themselves with a ripe female,
keeping their position by the use of spawning tubercles which cover their scales
and fin rays. The female and males vibrate in unison, causing the release of
eggs and sperm. Neither the female nor the males release all of their gametes
during any single spawning event, and multiple spawnings within and between tide
cycles are common.

Fertilized surf smelt eggs have morphological features which cause the eggs
to adhere to sand grains in which they are laid, giving stability to the
deposited spawn. The outer membrane of the egg ruptures and turns inside out,
forming a pedestal which is the point of the attachment. Wave action and tidal
exchange buries the weighted eggs to a depth of several millimeters. While the
eggs incubate in the sand they are "extra-aquatic", meaning they are
submerged in saltwater during a portion of the tidal cycle. Extra-aquatic
development is thought to be adaptive because the eggs are subjected to warmer
temperatures and therefore develop quicker. The eggs are also less available to
predation from birds and other fishes.

Development rates of surf smelt eggs vary greatly with seasonal ambient
temperature. Surf smelt eggs brooded in winter months may require between 27 and
56 days to hatch, while those brooded in summer months may required between 11
and 16 days. Regardless of the brooding time, hatching surf smelt eggs release
larva measuring about 3 mm which are at the mercy of the local tides and
currents. After about 3 months they have grown to about 30 mm and taken on their
adult form and coloration. Juvenile surf smelt rear in the near shore waters
throughout Puget Sound.

The majority of surf smelt will mature to spawn in their second year,
although a small proportion will spawn in their first year. Surf smelt do not
die after spawning and may spawn in successive seasons. Like herring, surf smelt
are thought to display some degree of homing, based on studies of their
geographically and temporally distinct spawning behavior, parasitology and
serology. The frequency of individual spawning and the degree to which
individual surf smelt stray between spawning grounds are unknown.

Like all other forage fish, surf smelt experience high predation levels as
eggs, juveniles and adults. As a result the maximum life span of a surf smelt is
thought to be 5 years. Adult surf smelt feed primarily on planktonic organisms,
and in turn are food for many marine animals such as seabirds, marine mammals,
and other fishes. The movements of juveniles and adults between spawning seasons
is virtually unknown.

"This is a reproduction of a Washington
Department of Fish and Wildlife document and is not the official document or
regulations of the Washington Department of Fish and Wildlife. The accuracy of
the reproduction cannot be guaranteed by WDFW."