Biology
provided by Arkive
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).
Conservation
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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.
Description
provided by Arkive
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).
Habitat
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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).
Range
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Previously abundant along all European coasts, this sturgeon is today restricted to a single, reproductive population that breeds in the Gironde River, France (5).
Status
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Classified as Critically Endangered (CR) on the IUCN Red List 2007 (1), and listed on Appendix I of CITES (3).
Threats
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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).
Diagnostic Description
provided by Fishbase
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).
Life Cycle
provided by Fishbase
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).
Migration
provided by Fishbase
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.
Morphology
provided by Fishbase
Dorsal spines (total): 0; Dorsal soft rays (total): 30 - 44; Analspines: 0; Analsoft rays: 23 - 30
Trophic Strategy
provided by Fishbase
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).
Biology
provided by Fishbase
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).
Importance
provided by Fishbase
fisheries: commercial; aquaculture: commercial
European sea sturgeon
provided by wikipedia EN
The European sea sturgeon (Acipenser sturio), also known as the Atlantic sturgeon or common sturgeon, is a species of sturgeon native to Europe. It was formerly abundant, being found in coastal habitats all over Europe. It is anadromous and breeds in rivers. It is currently a critically endangered species.[1] Although the name Baltic sturgeon sometimes has been used, it has now been established that sturgeon of the Baltic region are A. oxyrinchus, a species otherwise restricted to the Atlantic coast of North America.[5]
Description
Head of a European sea sturgeon
The wedge-shaped head of the European sea sturgeon ends in a long point. There are many sensitive barbels 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 6 m (20 ft) and 400 kg (880 lb) in weight, but a more common length is 1.25 m (4 ft 1 in).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
Until the first decades of the twentieth century, these fish were locally abundant in Europe and were caught extensively for their caviar, but a sharp decline due to overfishing (which greatly accelerated from the second half of the nineteenth century onwards) led to their disappearance from the vast majority of their former ranger. They 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 river basin in France.[6] Conservation projects involving this species include reintroductions based on specimens from aquaculture with the first releases in 1995.[1] For example, 87 sturgeons were experimentally released in the Rhine near Nijmegen in 2012 and 2015.[7]
Diet
Like other sturgeons, they eat polychaete worms and crustaceans which they find with their barbels.[8]
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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^ a b c Gessner, J.; Williot, P.; Rochard, E.; Freyhof, J. & Kottelat, M. (2022). "Acipenser sturio". IUCN Red List of Threatened Species. 2022: e.T230A137215851. doi:10.2305/IUCN.UK.2022-1.RLTS.T230A137215851.en. Retrieved 21 March 2023.
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^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
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^ Froese, R.; Pauly, D. (2017). "Acipenseridae". FishBase version (02/2017). Retrieved 18 May 2017.
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^ "Acipenseridae" (PDF). Deeplyfish- fishes of the world. Retrieved 18 May 2017.
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^ Ludwig, A; Arndt, U; Lippold, S; Benecke, N; Debus, L; King, T. L.; Matsumura, S (2008). "Tracing the first steps of American sturgeon pioneers in Europe". BMC Evolutionary Biology. 8: 221. doi:10.1186/1471-2148-8-221. PMC 2527320. PMID 18664258.
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^ "Protection of common sturgeon: advice for fishermen". gov.uk. January 16, 2017.
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^ Brevé, N. W., Vis, H., Houben, B., Breukelaar, A., & Acolas, M. L. (2019). Outmigration pathways of stocked juvenile European sturgeon (Acipenser sturio L., 1758) in the Lower Rhine River, as revealed by telemetry. Journal of Applied Ichthyology, 35(1), 61-68.
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^ 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.
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European sea sturgeon: Brief Summary
provided by wikipedia EN
The European sea sturgeon (Acipenser sturio), also known as the Atlantic sturgeon or common sturgeon, is a species of sturgeon native to Europe. It was formerly abundant, being found in coastal habitats all over Europe. It is anadromous 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 are A. oxyrinchus, a species otherwise restricted to the Atlantic coast of North America.
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