The European sea sturgeon (''Acipenser sturio''), also known as the Atlantic sturgeon or common sturgeon, is a species of

sturgeon Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...

native to Europe. It was formerly abundant, being found in coastal habitats all over

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. It is

anadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...

and breeds in rivers. It is currently a critically endangered species. Although the name Baltic sturgeon sometimes has been used, it has now been established that sturgeon of the

Baltic region The terms Baltic Sea Region, Baltic Rim countries (or simply the Baltic Rim), and the Baltic Sea countries/states refer to slightly different combinations of countries in the general area surrounding the Baltic Sea, mainly in Northern Europe. ...

are '' A. oxyrinchus'', a species otherwise restricted to the Atlantic coast of North America.

Description

The wedge-shaped head of the European sea sturgeon ends in a long point. There are many sensitive

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprinid ...

s on the facial area. The dorsal fins are located very far back on the body. Five longitudinal lines of large osseous plates are found on the body of the fish. The stomach is yellow and the back is a brownish grey. This sturgeon can reach and in weight, but a more common length is .They can reach an age of 100 years, and have a late sexual maturity (12 to 14 years for the males and 16 to 18 years for the females).

Distribution and habitat

They are found on the coasts of Europe, except in the northernmost regions and the Baltic region, and have rarely even been known to cross the Atlantic Ocean to the coasts of North America. Like many other sturgeons, they spawn in the rivers inland from the coast. The species can tolerate wide spread salinities and spend most of their lives in saltwater but migrate to spawn in freshwater.

Conservation

At the beginning of the 19th century, these fish were used extensively to produce

caviar Caviar (also known as caviare; from fa, خاویار, khâvyâr, egg-bearing) is a food consisting of salt-cured roe of the family Acipenseridae. Caviar is considered a delicacy and is eaten as a garnish or a spread. Traditionally, the te ...

, but have been a protected species in Europe since 1982. Despite their estimated range of distribution, they have become so rare that they only breed in the

Garonne The Garonne (, also , ; Occitan, Catalan, Basque, and es, Garona, ; la, Garumna or ) is a river of southwest France and northern Spain. It flows from the central Spanish Pyrenees to the Gironde estuary at the French port of Bordeaux – ...

river basin in France. Conservation projects involving this species include

reintroduction Species reintroduction is the deliberate release of a species into the wild, from captivity or other areas where the organism is capable of survival. The goal of species reintroduction is to establish a healthy, genetically diverse, self-sustainin ...

s based on specimens from

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

with the first releases in 1995. For example, 87 sturgeons were experimentally released in the

Rhine ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , source ...

near

Nijmegen Nijmegen (;; Spanish and it, Nimega. Nijmeegs: ''Nimwèège'' ) is the largest city in the Dutch province of Gelderland and tenth largest of the Netherlands as a whole, located on the Waal river close to the German border. It is about 6 ...

in 2012 and 2015.

Diet

Like other sturgeons, they eat polychaete worms and

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean g ...

which they find with their barbels.Brosse, L., Taverny, C., & Lepage, M. (2011). Habitat, movements and feeding of juvenile European sturgeon (Acipenser sturio) in Gironde Estuary. In Biology and Conservation of the European SturgeonAcipenser sturioL. 1758 (pp. 153-163). Springer, Berlin, Heidelberg.

Threats

Historical habitat changes to the European sturgeon, such as gravel extraction from riverbeds and damming of the Dordogne and Garonne Rivers, have resulted in a reduction in the number of available spawning sites, contributing to the species' low abundance and regional dispersion. Furthermore, despite recent gains in compliance with fisheries bans, bycatch in commercial benthic trawls and gillnet fisheries threatens reintroduction attempts and is regarded the biggest threat to the remaining population and a major impediment to the species' recovery.

Population

Although no specific population estimates are available, the abundance of wild, mature European Sturgeon is estimated to be less than 800 individuals. The last time the species hatched was in the Garonne River in France in 1994, and genetic analysis reveals that the 1994 cohort was formed by only one mating pair. Because the wild population is so small, a captive breeding and stocking program is vital to the species' survival. Although restoration operations, such as artificially bred individual restocking, have been successful in the Gironde estuary and the Elbe River (Germany), recovery for the European sturgeon is a long process that might take 30-50 years. Bycatch in commercial trawls and gillnets, pollution, climate change, and potential competition with other species are all dangers to the species right now.

Scientific Classification

References

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External links

*ARKive
images and movies of the European sea sturgeon''(Acipenser sturio)''
{{Authority control European sea sturgeon Fish of the Atlantic Ocean Fish of the North Sea Freshwater fish of Europe Marine fish of Europe Critically endangered fish Critically endangered biota of Europe European sea sturgeon Taxa named by Carl Linnaeus