E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Acipenser medirostris Ayres, 1854
Green Sturgeon
Family: Acipenseridae

Photo of species

© Public Domain  Email the photographer   (Photo ID #16406)

Distribution of Acipenser medirostris in British Columbia.
Source: Distribution map provided by Don McPhail for E-Fauna BC
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The green sturgeon is a long-lived, slow growing, species that spends most of its adult life at sea, primarily in nearshore oceanic waters, bays, and estuaries--although, as juveniles, they spend 1-4 years in freshwater or in estuaries (McPhail 2007, NOAA Fisheries 2010). This species is usually dark green in colour on the back and flanks, and sports a "midventral dark, arro-like stripe on the belly that is a useful field character." (McPhail 2007). Although green sturgeon are classified as bony fish, the skeleton is mostly comprised of cartilage (NOAA Fisheries 2010). This species lacks scales, but has five rows of bony plates on the body (NOAA Fisheries 2010).

NOAA Fisheries (2010) provides the following reproduction information: "Early life-history stages reside in fresh water, with adults returning to freshwater to spawn when they are more than 15 years of age and more than 4 feet (1.3 m) in size. Spawning is believed to occur every 2-5 years (Moyle, 2002). Adults typically migrate into fresh water beginning in late February; spawning occurs from March-July, with peak activity from April-June (Moyle et al., 1995). Females produce 60,000-140,000 eggs (Moyle et al., 1992)."

McPhail (2007) reports that once they leave their spawning streams, green sturgeon migrate rapidly northwards, and likely travel in schools. Diet of adults includes shrimp, mollusks, amphipods, and small fish (NOAA Fisheries 2010).

The Committee on the Status of Wildlife in Canada (COSEWIC) list this species as "special concern". In British Columbia, it is illegal to keep green sturgeon and catches must be returned alive to the water.

Read the NOAA Fisheries (2010) page on this species for additional detailed information.

Species Information

Dorsal spines (total): 0; Dorsal soft rays (total): 33 - 35; Anal spines: 0; Anal soft rays: 22 - 28. Characterized by a single row of 1 to 4 bony plates along the midventral line between the anus and the anal fin, and about 33 to 35 rays in the dorsal fin. Dorsal arises at posterior third of the total length; anal fin arises under posterior part of dorsal; pectorals originate low on the body just behind gill opening and are large and rounded; pelvic fins arise near the anus. Generally olive to dark green, lower parts more or less whitish green; a longitudinal olive-green stripe on side between lateral and ventrolateral plates, another on midventral surface; fins grayish to pale green.

Source: FishBase. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p


Species Biology

Found in estuaries, lower reaches of large rivers, and in salt or brackish water off river mouths. Probably spawns in fresh water. May cover considerable distances in the ocean.

Source: FishBase. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p


BC Distribution and Notes

The green sturgeon is an occasional visitor to B.C. marine and estuarine waters. There is no evidence that this species breeds in either the Columbia or Fraser river systems even though it is seasonally common in the Columbia estuary. The source of both the Columbia and our green sturgeons appears to be the Klamath River

Source: Information provided by Don McPhail for E-Fauna BC.
Global Distribution

North America: Aleutian Islands and the Gulf of Alaska to Ensenada, Mexico. Considered vulnerable in Canada. The Asian population is now considered to be a separate species Acipenser mikadoi.

Source: FishBase. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeS1NBlueSC (Nov 2013)
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Notes

McPhail (2007) reports that there are records for this species from the lower Fraser River, including a recent one from Fort Langley in 2005. He also indicates that most BC records are "from the sea off the west coast of Vancouver Island or from northern estuaries (e.g. the Skeena, Nass, and Taku estuaries)."

Additional Range and Status Information Links

Additional Photo Sources

Species References

Froese, R. and D. Pauly. Editors. 2010.FishBase. World Wide Web electronic publication. www.fishbase.org.

McPhail, J. D. 2007. The Freshwater Fishes of British Columbia. The University of Alberta Press, Edmonton.

Page, L.M. and B.M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p.

General References

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-06-16 3:07:45 AM]
Disclaimer: The information contained in an E-Fauna BC atlas pages is derived from expert sources as cited (with permission) in each section. This information is scientifically based.  E-Fauna BC also acts as a portal to other sites via deep links.  As always, users should refer to the original sources for complete information.  E-Fauna BC is not responsible for the accuracy or completeness of the original information.

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