Species Profile

Green Sturgeon

Scientific Name: Acipenser medirostris
Taxonomy Group: Fishes
Range: British Columbia, Pacific Ocean
Last COSEWIC Assessment: November 2013
Last COSEWIC Designation: Special Concern
SARA Status: Schedule 1, Special Concern


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Quick Links: | Photo | Description | Habitat | Biology | Threats | Protection | National Recovery Program | Documents

Image of Green Sturgeon

Green Sturgeon Photo 1

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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 meters and maximum weight of 159 kilograms. Males generally mature at 15 years of age, while females mature at 17 years. Green Sturgeon is anadromous, meaning it returns to freshwater 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 meters and maximum weight of 816 kilograms, substantially larger than its Green Sturgeon counterpart.

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Distribution and Population

Green Sturgeon are 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 the Canadian Green Sturgeon population, and its population trends are not known.

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Habitat

Green Sturgeon are 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 are usually found in saltwater, but occupies freshwater 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.

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Biology

There is little information on the general biology of the Green Sturgeon. Green Sturgeon are anadramous but spend the majority of their time in the marine environment. They are long-lived species, having been recorded to reach an age of 42 years, although it is possible that Green Sturgeon can reach ages of 60-70 years. Although spawning is not known to occur in Canadian waters, it is known that mature adults migrate up rivers to spawn from March to July. Juveniles migrate downstream as they grow, and move into estuaries within the first year and a half of life where they reside for one to two years. Migration to marine waters occurs between 2.5 to 3.5 years. Males spend three to nine years while females spend three to fifteen years at sea before returning to freshwater to spawn. Green Sturgeon reach sexual maturity at 14 to 20 years, and reproduce every to two to five years. Females can produce 60,000 to 140,000 large eggs, reaching maximum fecundity at 24 years.

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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.

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Protection

Federal Protection

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 highlights the management objectives and strategies for maintaining sustainable population levels of the species. Additionally, under the Fisheries Act’s BC Sport Fishing Regulations, it is illegal to retain any Green Sturgeon caught while sport fishing in Canada.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Documents

PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

14 record(s) found.

COSEWIC Status Reports

  • COSEWIC assessment and update status report on the green sturgeon Acipenser medirostris in Canada (2005)

    The green sturgeon (A. medirostris) is easily distinguished from other families of fish by a combination of features including four barbels in front of a subterminal mouth, five rows of bony scutes, a heterocercal tail, an elongate snout, a single fleshy dorsal fin located near the caudal peduncle, and a largely cartilaginous endoskeleton. Green sturgeon are generally dark olive green with a white belly. Due to range overlap and similar appearance, green sturgeon can be easily confused with the white sturgeon (A. transmontanus). The green sturgeon spawns in freshwater but spends the majority of its lifecycle in the marine environment and is reported to reach a maximum length and weight of 2.3 m and 159 kg.

COSEWIC Assessments

  • COSEWIC Assessment - Green Sturgeon (2005)

    Designated Special Concern in April 1987. Stats re-examined and confirmed in November 2004. Last assessment based on an update status report.
  • COSEWIC status appraisal summary on the Green Sturgeon Acipenser medirostris in Canada (2014)

    This is a large-bodied fish species that is slow to grow and mature. The number of individuals in Canadian waters is unknown, but is undoubtedly not large. This species is globally at risk, and known threats are fisheries by-catch in both Canada and the United States, and habitat loss and degradation owing to water extraction, industrial and recreational development, and construction of dams in the United States where all known spawning locations are found.

Response Statements

  • Response Statement - Green Sturgeon (2015)

    This is a large-bodied fish species that is slow to grow and mature. The number of individuals in Canadian waters is unknown, but is undoubtedly not large. This species is globally at risk, and known threats are fisheries by-catch in both Canada and the United States, and habitat loss and degradation owing to water extraction, industrial and recreational development, and construction of dams in the United States where all known spawning locations are found.
  • Response Statements - Green Sturgeon (2005)

    The number of individuals in Canadian waters is unknown, but is undoubtedly not large. This species is globally at risk and is of concern in Canada because of exploitation and habitat loss due to damming of rivers.

Action Plans

  • Multi-species Action Plan for Gwaii Haanas National Park Reserve, National Marine Conservation Area Reserve, and Haida Heritage Site (2016)

    The Multi-species Action Plan for Gwaii Haanas National Park Reserve, National Marine Conservation Area Reserve, and Haida Heritage Site meets the requirements for an action plan set out in the Species at Risk Act (SARA (s.47)) for species requiring an action plan that occur inside the boundary of the site. This action plan will be updated to more comprehensively include measures to conserve and recover the marine species at risk once the first integrated Land, Sea, People management plan for Gwaii Haanas National Park Reserve, National Marine Conservation Area Reserve & Haida Heritage Site (hereafter called Gwaii Haanas) is complete. Measures described in this plan will also provide benefits for other species of conservation concern that regularly occur in Gwaii Haanas.

Management Plans

  • Management Plan for the Green Sturgeon (Acipenser medirostris) in Canada (2017)

    The Green Sturgeon (Acipenser medirostris) is an anadromous fish that was originally assessed in November 2004 as ‘special concern’ by the Committee for the Status of Endangered Wildlife in Canada (COSEWIC), and recently reassessed under the same status in November 2013. Green Sturgeon was listed as a species of Special Concern under the Species at Risk Act (SARA) in September 2006 and is currently listed as such. Green Sturgeon are thought to represent an early evolutionary offshoot from primitive bony fish, dating back about 200 million years. These large fish can reach a maximum size of 2.3 metres and 159 kg (Scott and Crossman 1973). The ventral surface is white with a dark olive stripe extending down the middle of the belly, often terminating anterior to the pectoral fins (Scott and Crossman 1973). Green Sturgeon are found in the shallower waters of the continental shelf (i.e., less than 110 metres) along the western coast of North America, from Mexico to southeastern Alaska. This range overlaps with that of White Sturgeon (Acipenser transmontanus), thus it is important to distinguish between the two species as they are generally similar in appearance.

Orders

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2005 (2005)

    2005 Annual Report to the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
  • COSEWIC Annual Report - 2013-2014 (2014)

    Under Canada’s Species at Risk Act (SARA), the foremost function of COSEWIC is to "assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species". COSEWIC held two Wildlife Species Assessment Meetings in this reporting year (October, 2013 to September, 2014) from November 24 to November 29, 2013 and from April 27 to May 2, 2014. During the current reporting period, COSEWIC assessed the status or reviewed the classification of 56 wildlife species. The wildlife species assessment results for the 2012-2013 reporting period include the following: Extinct: 0 Extirpated: 0 Endangered: 23 Threatened: 12 Special Concern: 20 Data Deficient: 0 Not at Risk: 1 Total: 56 Of the 56 wildlife species examined, COSEWIC reviewed the classification of 40 that had been previously assessed. The review of classification for 25 of those wildlife species resulted in a confirmation of the same status as the previous assessment.

Consultation Documents

  • Consultation on Amending the List of Species Under the Species At Risk Act: November 2005 (2005)

    The Government of Canada proclaimed the Species at Risk Act (SARA) on June 5, 2003 as part of its strategy for the protection of wildlife species at risk. Attached to the Act is Schedule 1, the list of the species that receive protection under SARA, hereinafter referred to as the 'SARA list'. Canadians are invited to comment on whether all or some of the species included in this document should be added to the SARA list.
  • Species at Risk Act Legal Listing Consultation Workbook: North Pacific Right whale, Fin whale, Green sturgeon, and Bering cisco (2005)

    Your opinion is being sought to assist the government of Canada in making an informed decision on whether to add the North Pacific Right whale, Fin whale, Green sturgeon, and Bering cisco to the Schedule 1 (the List of Wildlife Species at Risk) of the Species at Risk Act (SARA). Your input on the impacts of adding these species to the List is important. This workbook has been developed to give you an opportunity to provide Fisheries and Oceans Canada with your feedback, advice, and other comments regarding adding these species to Schedule 1 of SARA (Schedule 1 identifies which species are legally protected under SARA).

Recovery Document Posting Plans

  • Recovery Document Posting Plan - Fisheries and Oceans Canada - Fiscal Year 2016-2017 (2016)

    Under the Species at Risk Act (SARA), the competent Minister(s) must prepare a recovery strategy within one year of listing a species on Schedule 1 of SARA as endangered and within two years of listing a species as extirpated or threatened. A management plan must be prepared within three years for a species listed as special concern. Fisheries and Oceans Canada (DFO) is accountable for 111 of the 518 species listed under SARA. As of February 2016, proposed recovery strategies, management plans and action plans for 57 of those species have not yet been posted to the Species at Risk Public Registry. An additional 23 aquatic species have proposed management or action plans coming due in the future. The following outlines the Department’s plan for posting proposed documents for 64 species on the Species at Risk Public Registry. The Department has a plan to post recovery strategies for 9 species, management plans for 13 species, and action plans for 42 species over the next year.