European Sturgeon (Acipenser sturio)
Did You Know?
|Weight:||up to 2,200 pounds (1,000 kg)|
|Length:||20 feet (6 m)|
|Appearance:||olive-black with a white belly; they have 5 major rows of "scutes"|
|Lifespan:||uncertain, but likely up to 50 years|
|Diet:||worms, crustaceans, mollusks|
|Behavior:||they migrate upriver in spring to spawn|
European sturgeon are large, long-lived, estuarine-dependent, "anadromous" fish. They can grow to 16-20 feet (5-6 m) long and can weigh up to 2,200 pounds (1,000 kg). They are olive-black with white belly. They have five major rows of dermal scutes. They have an elongated body with a narrow-tipped snout. Their mouth is interrupted at the center of their lower lip.
European sturgeon are "benthic" feeders and typically forage on benthic invertebrates. Their reproductive phase begins at 10-18 years old, later than many other sturgeons, with males reproducing for the first time at 10-12 years and females at 13-18 years. Size at maturity varies from about 3-4 feet (0.9-1.3 m) in males and about 3-6 feet (0.9-1.8 m) in females.
Atlantic and European sturgeons are closely related. At one time, they were considered two sub-species: A. sturio oxyrinchus and A. sturio sturio, respectively. In 1963, they were separated into two species (A. oxyrinchus, A. sturio) based on morphological and meristic characters.
They live in both marine and freshwater. They spawn in freshwater, and then mature from juvenile to adult in marine waters near the shore. Then, as adults, they return to freshwater to spawn. They can tolerate a wide range of salinities.
Juveniles make a slow descent downstream to the estuary and are present in the upper estuary of their birth rivers at one year of age. Juveniles enter the sea after 2-6 years, during which they alternate movement between the sea and spending the winter in the estuary. For the next 4-6 years, they enter the lower estuary at summer time and return to the sea in the fall. As adults, they are generally found close to shore in the sea and are never found in waters deeper than 650 feet (200 m).
- France (southwestern)
- Gironde estuary
- Dordogne River
- Garonne River
- Georgia (western)
- Rioni basin, population last reproduced in 1991
Historically, European sturgeon were abundant in the North Sea, the English Channel, and most European coasts of the Atlantic Ocean, the Mediterranean Sea, and the Black Sea.
The current population size is roughly estimated at 20-750 adults. European sturgeon are thought to have declined by at least 90% over the past 75 years. No natural reproduction has been documented in the wild since 1994.
Large numbers have been stocked from hatchery programs in the past few years, but they have not yet reproduced:
- 7,000 in 2007
- 80,000 in 2008
- 46,000 in 2009
- overfishing led to widespread declines in European sturgeon abundance
- commercial and recreational fishing occurred since the fifth century B.C. but is now generally banned
Current threats include:
- "bycatch" of sturgeon in fisheries targeting other species
- habitat degradation and loss from various human activities such as dredging, dams, water withdrawals, and other development
- habitat impediments including locks and dams
- pollution and poor water quality
- small population size
- competition from other introduced sturgeon
European sturgeon are listed in Appendix I of CITES, which regulates international trade.
They are listed in Appendix II of the Bern Convention on the Conservation of European Wildlife and Natural Habitats, which prohibits "take" and deliberate habitat destruction. All countries that have signed the convention must coordinate efforts to protect at-risk species and promote:
- national conservation policies
- measures against pollution
- educational and informative measures
They are also listed in Appendix I of the Convention on Migratory Species.
Most nations in the species range protect the species through national law. Extensive stocking programs exist, especially in France and Germany.
In 2012, WildEarth Guardians and Friends of Animals petitioned [pdf] us to list 15 foreign sturgeon species under the ESA. We proposed to list 5 species as endangered under the ESA. (The other 10 species were determined to be under the jurisdiction of the U.S. Fish and Wildlife Service, and USFWS is reviewing their status.)
|Final Endangered Listing of Five Sturgeon Species||79 FR 31222||06/02/2014|
Proposed Endangered Listing of Five Species of Sturgeons under the ESA
|78 FR 65249||10/31/2013|
|90-day Finding on a Petition To List Five Species of Sturgeon as Threatened or Endangered under the ESA||77 FR 51767||08/27/2012|
|Petition to List 15 Sturgeon Species as Threatened or Endangered||n/a||various|
- Endangered and Threatened (ESA-listed) Sturgeon:
- Endangered and Threatened (ESA-listed) Fish
Updated: June 2, 2014