Acipenser transmontanusOregon sturgeon(Also: Pacific sturgeon; Sacramento sturgeon)

Ge­o­graphic Range

The White Stur­geon is found on the Pa­cific slope of North Amer­ica from the Aleut­ian Is­lands, AK to Baja, CA. It is anadro­mous fish, spend­ing most of its life in sea near the shore and can be found in es­tu­ar­ies of large rivers. It mi­grates far in­land in large rivers to spawn. (Kee, et. al. 1981; Boschung, 1985).

Habi­tat

His­tor­i­cally, white stur­geon spent their life in sev­eral habi­tats; streams, rivers, es­tu­ar­ies, and ma­rine wa­ters. They are anadro­mous fish but may spend much or all of their lives in fresh water if they can­not reach the sea (Hart 1973). White stur­geon his­tor­i­cally oc­curred on the Pa­cific Coast, re­pro­duc­ing in at least three large river sys­tems, in­clud­ing Sacra­mento-San Joaquin River in Cal­i­for­nia, the Co­lum­bia River basin in the Pa­cific North­west, and the Fraser River sys­tem in British Co­lum­bia (Fish and Wildlife Ser­vice, In­te­rior, 1994). The build­ing of dams along the rivers has im­pacted the pop­u­la­tions of white stur­geons by cre­at­ing land­locked pop­u­la­tions and de­stroy­ing spawn­ing grounds.

White stur­geon are still dis­trib­uted through­out the river sys­tems of the Pa­cific north­west, but these pop­u­la­tions are iso­lated and their mi­gra­tion is lim­ited within the se­ries of pools and lakes that make up these new dammed rivers (Pa­cific States Ma­rine Fish­eries Com­mis­sion, 2000)

  • Aquatic Biomes
  • rivers and streams
  • coastal

Phys­i­cal De­scrip­tion

There are sev­eral dis­tin­guish­ing char­ac­ter­is­tics of the white stur­geon. Its body is elon­gate and cylin­dri­cal and can be large, with sizes as large as 3.8 to 6 me­ters and weights as high as 630 kg.

It has no scales but five rows of "scutes" along the body. There are 11-14 plates in front of the sin­gle dor­sal fin, 38-48 plates from the head along the cen­tral cau­dal axis, and 9-12 from the head to the pelvic fins. Dor­sal color is light gray while the ven­tral sur­face is white.

The mouth is ven­tral, mod­er­ate in size and di­rected down­ward. The white stur­geon has no teeth, in­stead using its 'vac­uum cleaner' like mouth that is ca­pa­ble of si­phon­ing up food. This fish is rec­og­nized by its short broad snout with four bar­bels closer to the tip of the snout than the mouth. (Hart, 1973; Pa­cific States Ma­rine Fish­eries Com­mis­sion 1996).

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    630 (high) kg
    1387.67 (high) lb

Re­pro­duc­tion

The exact re­pro­duc­tive win­dow for white stur­geon is not known, how­ever for stur­geons in gen­eral the males re­pro­duce for 10 to 20 years and fe­males for 15 to 25 years. The size or age of ma­tu­rity is vari­able, and spawn­ing oc­curs when the phys­i­cal en­vi­ron­ment per­mits vitel­lo­ge­n­e­sis (egg de­vel­op­ment) and cues ovu­la­tion. Land­locked stur­geons have been ob­served to spawn dur­ing pe­ri­ods of peak river flow with high water ve­loc­i­ties that dis­perse and pre­vent clump­ing of the eggs. White stur­geon are broad­cast spawn­ers be­cause they re­lease their eggs and sperm in fast water. In­for­ma­tion from Fish and Wildlife Ser­vice (1994)

  • Average age at sexual or reproductive maturity (female)
    Sex: female
    8212 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    6022 days
    AnAge

Lifes­pan/Longevity

Be­hav­ior

White stur­geon are slow grow­ing, late ma­tur­ing, anadro­mous fish.

Adults spend most of their time in sea near the shore, but they have been found in depths of 30 me­ters. Adults move into large rivers in early spring and spawn by May or June. They can as­cend far in­land to spawn (Lee 1980). Land­locked fish also mi­grate. Tag­ging stud­ies of Kootemai river white stur­geon re­vealed that in spring, the fish were ob­served to have moved up­river 16 to 114 river kilo­me­ters, and re­mained con­gre­gated in spe­cific lo­ca­tions through the sum­mer. The fish that were seden­tary dur­ing the sum­mer in­hab­ited the deep­est holes of the river (Fish and Wildlife Ser­vice 1994).

Com­mu­ni­ca­tion and Per­cep­tion

Food Habits

White Stur­geon have been de­scribed as op­por­tunis­tic feed­ers, feed­ing on the bot­tom with their long snouts and using their bar­bels to de­tect food. When small they feed on clams, mus­sels, cray­fish, worms, and fish eggs. At a larger size, they prey on fish such as smelt, an­chovies, lam­prey, shad and salmon.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

The size com­bined with the "char­ac­ter­is­tic qual­ity of its flesh" makes it a valu­able game fish in areas were it is not pro­tected. Its roe can be used for caviar, and Co­lum­bia river roe pro­duc­tion is "sec­ond only to the for­mer So­viet Union" (Hart 1973; Pa­cific States Ma­rine Fish­eries Com­mis­sion 1996).

Con­ser­va­tion Sta­tus

In 1994, the pop­u­la­tion of White Stur­geon lo­cated in the Koote­nai river was granted en­dan­gered sta­tus. The pop­u­la­tion has been de­clin­ing since the 1960's and there has been a com­plete lack of re­cruit­ment of breed­ing ju­ve­niles in the pop­u­la­tion since 1974. The de­cline cor­re­sponds to the open­ing of the Libby Dam in Mon­tana and pos­si­bly from poor water qual­ity and the ef­fects of con­t­a­m­i­nants (Fish and Wildlife Ser­vice 1994).

Joint ef­forts be­tween Canada and the United States are un­der­way to ad­dress the needs of the Koote­nai pop­u­la­tion by de­vel­op­ing a re­gional re­cov­ery strat­egy (Duke, 2000).

Other Com­ments

White Stur­geons are the largest fresh­wa­ter fish in North Amer­ica. The largest white stur­geon was taken from the Snake River in Idaho in 1898 and it weighed 682 kilo­grams (Duke 2000).

The name comes from "acipenser," an Old World name mean­ing stur­geon and trans­mon­tan­ta­nus mean­ing be­yond the moun­tains. This seems fit­ting for a fish found west in the New World (Pa­cific States Ma­rine Fish­eries Com­mis­sion 1996).

Con­trib­u­tors

William Fink (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Charles Der­shimer (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

tactile

uses touch to communicate

Ref­er­ences

Boschung, H. 1985. The Audubon So­ci­ety Field Guide to North Amer­i­can Fishes, Whales, and Dol­phins. New York: AAl­fred A. Knopf, Inc..

Duke, S. March 3, 2000. "The Koote­nai River Pop­u­la­tion of White Stur­geon" (On-line). Ac­cessed Sun­day, Oc­to­ber 22, 2000 at http://​endangered.​fws.​gov/​features/​sturgeon/​.

Fish and Wildlife Ser­vice, In­te­rior, Sep­tem­ber 6, 1994. "En­dan­gered and Threat­ened Wildlife and Plants; De­ter­mini­a­tion of En­dan­gered Sta­tus for the Koote­nai River Pop­u­la­tion of the White Stur­geon" (On-line). Ac­cessed Oc­to­ber 22, 2000 at http://​endangered.​fws.​gov/​r/​fr94549.​html.

Hart, J. 1973. Pa­cific Fishes of Canada.. Ot­tawa: Fish­eries Re­search Board of Canada.

Kee, S. 1981. Atlas of North Amer­i­can Fresh­wa­ter Fishes. North Car­olina: North Car­olina State Mu­seum of Nat­ural His­tory.

Pa­cific States Ma­rine Fish­eries Com­mis­sion, De­cem­ber 16, 1996. "White Stur­geon" (On-line). Ac­cessed Oc­to­ber 24, 2000 at http://​www.​psmfc.​org/​habitat/​edu_​wsturg_​fact.​html.