Sturgeons are generally solitary, spending a number of years at sea before returning to the river where they were born, in order to breed in their turn. Entering the river in spring, mature individuals migrate upriver to the shallow spawning grounds (4). Females can produce between 200,000 and 6 million eggs, which are sticky so that they can attach to the gravel substrate (4). Mature individuals do not eat throughout the spawning migration (4). As the juveniles grow they begin to migrate downstream, and adult fish spend about seven to eight years at sea before reaching sexual maturity (7). Sturgeon feed opportunistically on bottom dwelling creatures, feeling for prey amongst the mud with the sensitive barbels on their chin. Their food consists mainly of invertebrates and small fish (4).

One of the largest European fish to breed in rivers, the European sea sturgeon has been fished to the brink of extinction principally as a source of caviar (2). This sturgeon has an olive-black upper body and a white belly (4). The elongated body tapers to a narrow pointed tip at the snout and lacks scales, apart from the five rows of whitish bony platelets, or scutes, which run the length of the fish (4). European sea sturgeon have sensitive barbels which are positioned on the lower jaw and are used to locate prey, which is then sucked into the mouth (4).

Amphihaline and anadromous fish (Ref. 51346, 51439), frequenting littoral zones (Ref. 2163, 51439, 51442). A long-lived and slow-growing species (Ref. 9988). It lives the major part of his life in sea but enters rivers for reproduction (Ref. 30578, 51442). Found on various substrates, from sand to rocks (Ref. 51346). At the sea, it occurs in coastal and estuarine zones. In freshwaters, it inhabits estuaries and large rivers (Ref. 59043). Juveniles found both in estuaries and in the sea (Ref. 2163), they slowly adapt to saltwater (Ref. 89103) and usually spend around 2-3 years in river estuaries before moving to the sea (Ref. 40152), some may migrate to the sea during their first summer (Ref. 59043). Usually solitary. Feeds on crustaceans, mollusks, polychaete worms and small fish. Today most males only reach 100-150 cm length, females 130-215 cm (Ref. 59043, 89104). Utilized fresh and frozen, and also for caviar; eaten steamed, pan-fried, broiled, boiled, microwaved and baked (Ref. 9988). A threatened species, mainly due to bycatch, poaching, habitat degradation (spawning grounds, nursery areas) and physical obstacles to migration (Ref. 26160).

 Acipenser sturio is a solitary species with a distinct morphology. Quite a large species, it can reach a total length of up to 5 m and a weight of 120 kg. Acipenser sturio has an olive-black upper body and a white belly. It has an elongated body which tapers to a narrow pointed tip at the snout, and lacks scales. It can be easily recognised by five rows of light-coloured bony platelets that run the length of the fish. Possessing no teeth, it uses conspicuous sensitive barbels on the lower jaw to locate prey which are sucked into the mouth.Acipenser sturio is a long-lived (up to 100 years) and slow-growing species. This has left it vulnerable to fishing pressure, and is now severely threatened by commercial fishermen targeting, in particular, the caviar contained within the females (Elvira, 2000).

Baltic sea, Bath, Belgian Exclusive Economic Zone, Black Sea, European waters (ERMS scope), IJsselmeer, Polish Exclusive Economic Zone, Portuguese Exclusive Economic Zone, Schelde estuary, Spanish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, Westerschelde, Wimereux, Zeeschelde

Eastern Atlantic: the only remaining spawning population occurs in the Garonne drainage in France (Ref. 59043, 89072). Used to range from Norway to the Bay of Biscay, including the North Sea, European coasts of Atlantic, northern Mediterranean eastward to Rhodos, western and southern Black Sea; occasionally recorded from the White Sea, Iceland, Morocco and Algeria. Anadromous, in most large rivers, but not recorded from Danube upriver of delta. Recent DNA studies using museum specimens revealed that this species co-exists with A. naccarii from the Adriatic Sea to the Iberian Peninsula (Ref. 52173). Several DNA sequence differences were found between individuals of the species from the Gironde River population and from the North and Baltic Seas showing that different populations of A. sturio are genetically divergent (Ref. 82476). Appendix II of the Bern Convention (2002). Appendix I and II of the Bonn Convention (2009). Annex II and IV of the EC Habitats Directive (2007). International trade banned (CITES I, since 29.7.83; CMS Appendix II).

This species was once known from the North and Baltic Seas, English channel, European coasts of Atlantic, northern Mediterranean west of Rhodos, and western and southern Black Sea. It was occasionally recorded in Algeria, Morocco and Tunisia. The last record from the Rioni (Georgia) was in 1991, although further surveys have failed to find the species (J. Gessner, pers comm.). Today this species is restricted only to the Garonne River (France).

Eastern Atlantic, Europe, Middle East: Western and southern Europe (including western Baltic Sea, North Sea, Mediterranean Sea, Black Sea, Sea of Marmara and adjacent watersheds).

Coastal waters from the St. Lawrence River to the Gulf of Mexico, running up into rivers to spawn; reported from Hudson Bay, also Scandinavia to the Mediterranean.

Previously abundant along all European coasts, this sturgeon is today restricted to a single, reproductive population that breeds in the Gironde River, France (5).

Dorsal spines (total): 0; Dorsal soft rays (total): 30 - 44; Analspines: 0; Analsoft rays: 23 - 30

Maximum size: 3500 mm TL

600 cm TL (male/unsexed; (Ref. 59043)); max. published weight: 400.0 kg (Ref. 556); max. published weight: 120 kg; max. reported age: 100 years (Ref. 556)

to 350.0 cm TL (male); 220.0 cm TL (female); max.weight: 400 kg (male); max.weight: 120 kg (female)

Body elongated, pentagonal section (Ref. 51442). Snout moderate with tip narrow and pointed (Ref. 3397), mouth inferior (Ref. 59043). Lower lip not continuous, interrupted at center (Ref. 3397). Four barbels halfway between snout tip and mouth but not reaching the latter (Ref. 3397, Ref. 51442). No scales, but 5 rows of scutes on the body: dorsal 9-16, lateral 24-39 on each side, ventral 9-14 on each side, with dense cross-lines of smaller rhombic plates between the dorsal and lateral rows (Ref. 2196, Ref. 3397, Ref. 40476, Ref. 51442). Dorsal side greenish-brown to blackish with golden tints, flanks light with silvery tints, belly white (Ref. 3397).

This taxon is one of a number of demersal species in the Seine River system of Western Europe. Demersal river fish are found at the river bottom, feeding on benthos and zooplankton

The Marne and Yonne exhibit the greatest torrential flows, due to the percentage of their courses underlain by impermeable strata, in combination with the river gradients. Although the Loing manifests the highest percentage of impermeable strata of all the tributaries, its low gradient mitigates against torrential velocities. Thus the majority of the Seine and its tributaries exhibit a relaxed generally even flow rate.

Seine water pollutant loads of heavy metals, nutrients, sediment and bacteria are relatively high, especially influnced by wastewater and surface runoff from Paris and its suburbs. Parisian pollutant loadings are noted to be particularly high during periods of high rainfall, not only due to high runoff, but also from the inadequate sewage treatment facilities in periods of high combined wastewater/stormwater flow.

Heavy metal concentrations at Poses weir reveal the following levels: copper, 1.9 milligrams per liter; cadmium, 32 mg/l; and lead, 456 mg/l. Concentrations of zinc are also quite high, making the Seine Estuary one of the most highly contaminated estuaries in the world with respect especially to lead and cadmium. Significant amounts of toxic pollutants are also attached to sediments deposited in the Seine during the last two centuries, including mercury, nickel, chromium, toluene, DDT and a variety of herbicides and pesticides. Downriver from Paris, significant quantites of ammonium are discharged into the Seine from effluent of the Achères wastewater treatment plant.

There are a total of 37 fish species inhabiting the Seine, and another two taxa that are known to have been extirpated in modern times. Two of the largest aquatic fauna known to have lived in the Seine are now locally extinct: the 500 centimeter (cm) long sturgeon (Acipenser sturio) and the 83 cm long allis shad (Alosa alosa).

The largest extant native demersal (species living on or near the river bottom) taxa in the Seine are:

the 133 cm European eel (Anguilla anguilla);

the 150 cm northern pike (Esox lucius);

the 120 cm sea lamprey (Petromyzon marinus); and,

the 152 cm Burbot (Lota lota).

demersal; anadromous (Ref. 51243); freshwater; brackish; marine; pH range: 7.5; dH range: 10 - 20; depth range 4 - 93 m (Ref. 51346), usually 5 - 60 m (Ref. 26160)

Habitat and Ecology

Systems

• Freshwater
• Marine

Depth range based on 1 specimen in 1 taxon.
Water temperature and chemistry ranges based on 1 sample.

Environmental ranges
  Depth range (m): 89 - 89
  Temperature range (°C): 7.020 - 7.020
  Nitrate (umol/L): 8.857 - 8.857
  Salinity (PPS): 35.129 - 35.129
  Oxygen (ml/l): 6.192 - 6.192
  Phosphate (umol/l): 0.765 - 0.765
  Silicate (umol/l): 4.624 - 4.624
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

 Acipenser sturio is a demersal species. It can tolerate a wide range of salinities. Most of its life is spent at sea, relatively close to the coast, but it enters rivers to spawn.

Depth: 5 - 60m.
From 5 to 60 meters.

Habitat: demersal. Amphihaline and potamodromous fish frequenting litoral zones. Juveniles found both in estuaries and in the sea (Ref. 2163). This species is usually solitary. Becoming rare (Ref. 4537). Feeds on crustaceans, molluscs, polychaete worms and small fishes. Eggs deposited on sand or gravel. A long-lived and slow-growing species (Ref. 9988). Utilized fresh and frozen, and also for caviar; eaten steamed, pan-fried, broiled, boiled, microwaved and baked (Ref. 9988).

demersal; freshwater; brackish; marine; pH range: 7.5; dH range: 10.0 - 20.0; depth range 5 - 60 m . Amphihaline and potamodromous fish frequenting littoral zones. Juveniles found both in estuaries and in the sea. Enters rivers to reproduce. Usually solitary.

Sturgeons are found near to the bottom of the water column, over a soft sandy or muddy substrate (6). Adults are found in the lower sections of large rivers and in the open sea, whilst spawning occurs upriver in shallow pools with a gravel base (6).

Anadromous. Fish that ascend rivers to spawn, as salmon and hilsa do. Sub-division of diadromous. Migrations should be cyclical and predictable and cover more than 100 km.

Solitary at present because rare (Ref. 231). Feeding ceases during migration and spawning (Ref. 89072). Adults feed on benthic invertebrates and fish (Ref. 231, 51442), larvae and juveniles feed on small crustaceans and insect larvae (Ref. 51442, 89072).

Feeds on crustaceans, mollusks, polychaete worms and small fishes.

Anadromous species, with adults migrating to the middle reaches of large rivers mainly in spring and early summer. Spawning occurs between March and August, when water temperature rises above 20 °C at depths of 2-10 m over stony bottoms in areas with strong current (1.5-2.0 m/s) (Ref. 51442, 59043, 89103).Mature individuals do not feed during spawning migration (Ref. 3193). Number of spawned eggs increases with age. After spawning adults return to the sea (Ref. 51442). The development of the sticky dark grey eggs (2.6-3.0 mm diameter) takes about one week at 17°C (Ref. 26160, 35388). It is suggested that males spawn every 2 years, females every 3-4 years (Ref. 89072). Upstream spawning migrations appear to be positively correlated with water levels in rivers and distances of 1,000 kilometres or more may be covered when water levels are high (Ref. 89104). Sturgeons in general have a high capacity for hybridization and most species are able to cross-breed (Ref. 89103, 89117). This species has been reported to cross-breed (albeit rarely) with the Danube sturgeon (Acipenser gueldenstaedti) (Ref. 89105).

Enters rivers from March/April to June/July, spawning over stones and gravel. Produces between 200,000 and 6 million eggs, with the numbers increasing with age; a fish of 150 kg may produce 4 million eggs . Mature individuals do not feed during spawning migration. The development of sticky eggs (2.6-3.0 mm diameter) takes about one week at 17°C.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Classified as Critically Endangered (CR) on the IUCN Red List 2007 (1), and listed on Appendix I of CITES (3).

Population

Population Trend

Critically Endangered (CR) (A2cde; B2ab(ii,iii,v))

Major Threats

These long-lived and slow-growing fish are very vulnerable to exploitation; the European sea sturgeon has been extensively fished for its highly prized flesh and for the eggs, which are sold as caviar (6). The development of river systems, in particular the construction of hydroelectric dams, destroys the breeding habitat of this species and adults are no longer able to return to their natal rivers to breed (8). Today only a single reproductive population remains and the species is consequently extremely vulnerable to extinction (5).

Conservation Actions

The European sea sturgeon is protected from international trade by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (3). A captive breeding programme (8) for the species is being undertaken with the long-term goal of reintroducing this 'dinosaur of the sea' to some of its former range.

fisheries: commercial; aquaculture: commercial