Green Sturgeon

Acipenser medirostris

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Green Sturgeon has a rounded body, small eyes, a sharp snout and a toothless ventral mouth with sensory barbels. The dorsal fin and pelvic fins are located towards the caudal fin (tail), which is broadly pointed. The pectoral fins are large and rounded. The body and upper part of the head are coloured dark green to olive green, while the lower part of the head is a paler green. The ventral surface is white, with a dark olive-green stripe extending down the middle of the belly, often terminating behind the pectoral fins. The pectoral fins are dusky grey to pale green. Sturgeons differ from other bony fish in that they have a cartilaginous skeleton instead of bone, and large bony plates (scutes) instead of scales.

The Green Sturgeon likely lives to 60 to 70 years old, and has a maximum length of 2.1 m and maximum weight of 159 kg. Males generally mature at 15 years of age, while females mature at 17 years. Green Sturgeon is anadromous, meaning it returns to fresh water to reproduce. Spawning is believed to occur every two to five years, with females producing between 60,000 and 140,000 eggs. Juveniles stay in rivers and estuaries for several years before dispersing widely into the marine environment.

In North America, the range of the Green Sturgeon overlaps with that of the White Sturgeon which is generally similar in appearance, but varies in size. An adult White Sturgeon has a maximum length of 6.1 m and maximum weight of 816 kg, substantially larger than its Green Sturgeon counterpart.

Habitat

Green Sturgeon is found along the western coast of North America, from Mexico to southeastern Alaska. The Canadian distribution of Green Sturgeon includes the entire coast of British Columbia, as it is part of the northward oceanic migration pattern for the species along the Pacific coast of North America. There is very little information on the size of Canada's Green Sturgeon population, and population trends are unknown.

Green Sturgeon is usually found in salt water, but occupies fresh water during the spawning season. Spawning occurs primarily in three rivers in the United States . Green Sturgeon is rarely encountered in fresh water in Canada, but will inhabit the brackish waters found at the mouth of large rivers; adult and subadult Green Sturgeon aggregate in non-natal estuaries in coastal bays for periods of up to several months during the marine phase of their life cycle. The reason for this aggregation is unclear, although it has been suggested that feeding does not occur during this time, and that aggregation is related instead to physiological requirements with respect to temperature.

Recent research has identified large concentrations of Green Sturgeon near Brooks Peninsula on northwest Vancouver Island during May through June and October through November, suggesting that important overwintering habitat might exist north of Vancouver Island and south of Cape Spencer, Alaska.

Threats

Although there are currently no directed commercial and recreational fisheries for this species, Green Sturgeon is occasionally caught incidentally in commercial groundfish trawl fisheries, commercial and First Nations salmon gillnet and beach seine fisheries, as well as recreational fisheries. Additionally, habitat loss can have impacts to Green Sturgeon, although the severity of the impact on these populations is unknown. Green Sturgeon is also at risk of exposure to Persistent Bioaccumulative Toxins (PBTs) during their freshwater and estuarine phases, and the species is vulnerable to chronic and acute effects of bioaccumulation due to its long lifespan. Although contaminant levels have not been measured in Green Sturgeon, White Sturgeon has been shown to carry high contaminant loads.

Overall, the threat of accidental mortality through fisheries bycatch is higher than the threats of habitat destruction and pollution; however, this threat is likely of lower risk in Canada. The main threats to Green Sturgeon are likely higher in the US portion of its range where known Green Sturgeon spawning and rearing habitats are located. These threats include freshwater habitat impacts from dams, dikes and other industrial activities that can affect the availability and suitability of habitats for successful reproduction and rearing.

Further Information

Worldwide, the Green Sturgeon is protected by international law under the Convention on International Trade of Endangered Species (CITES) that regulates the trade of this at risk species. The Green Sturgeon is also classified as ‘near threatened' on the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species.

In Canada, the Green Sturgeon is listed under the federal Species at Risk Act (SARA) as a species of Special Concern. More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide. A SARA Management Plan for Green Sturgeon in Canada is currently being developed. The management plan will highlight the management objectives and strategies for maintaining sustainable population levels of the species.

Provincially, the Green Sturgeon has been placed on the ‘Red List', the British Columbia's Ministry of Environment's tool to identify conservation priorities for species considered at risk in British Columbia. Additionally, under the federal Fisheries Act's British Columbia's Sport Fishing Regulations, it is also illegal to retain any Green Sturgeon caught while sport fishing in Canada.

In the United States, Green Sturgeon has been divided into two populations: the Northern population has been listed under the US Endangered Species Act as a Species of Concern, while the Southern population has been listed as Threatened under the legislation.

Visit the Species at Risk (SARA) Public Registry Profile

What can you do?

Green Sturgeon will get the protection they need only if all Canadians work together to reduce threats. Find out more about the Green Sturgeon and be aware of human-induced threats. Do your best to reduce threats wherever possible to better protect the Green Sturgeon and its habitat. Get involved with the Habitat Stewardship Program for Species at Risk (HSP) or a conservation organization.

Text Sources:

COSEWIC. 2004. COSEWIC assessment and update status report on the Green Sturgeon Acipenser medirostris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. Vii + 31 pp.

Lindley, S.T., Moser, M.L., Erickson, D.L., Belchik, M., Welch, D.W., Rechisky, E.L., Kelly, J.T., Heublein, J.C., and Klimley, A.P. 2008. Marine migration of North American Green Sturgeon. Trans. Am. Fish. Soc. 137(1): 182–194.

Moyle, P.B. 2002. Inland Fishes of California. University of California Press, Berkeley, California. 106-113 p.

Green Sturgeon

green sturgeon

D.W. Gotshall

Scientific Name: Acipenser medirostris
SARA Status: Special Concern (2013)
COSEWIC Status: Special Concern (2013)
Region: British Columbia

green sturgeon

D.W. Gotshall

green sturgeon

Oregon Department of Fish and Wildlife

green sturgeon

Oregon Department of Fish and Wildlife

green sturgeon

Oregon Department of Fish and Wildlife

Did You Know?

Road trip, anyone?
Green Sturgeon can be highly migratory. A U.S. study documented these fish as travelling one thousand kilometers. That's farther than going from Quebec City to Toronto!

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