Surf Smelt

Surf Smelt - Biology

Photo of 4 surf smelt.

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."