Beluga (sturgeon)
Beluga Temporal range: Pleistocene-recent[1]
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Huso huso | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Acipenseriformes |
Family: | Acipenseridae |
Genus: | Huso |
Species: | H. huso
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Binomial name | |
Huso huso | |
Synonyms[4][5] | |
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The beluga (
Etymology
The common name for the sturgeon, as for the unrelated beluga whale, is derived from the Russian word белый (belyj), meaning "white," probably referring to the extensive pale colour on the flanks and belly in beluga compared to that of other sturgeons.
Description
Huso huso shows typical characteristics of other sturgeon, such as an elongated body,
The dorsal fin has 48 to 81 soft rays, and the anal fin, much shorter, has 22 to 41 soft rays. There are five in a series of longitudinal scutes: dorsal (one series, 9–17 scutes), lateral (two series, one per side, 28–60 scutes each) and ventral series (two series, one per side, 7–14 scutes each). The surface of the skin is covered by fine denticles. The rostrum is conical and contains numerous sensory pits on both ventral and dorsal surfaces. The mouth is large, crescent-shaped and protractile, with the upper lip continuous while the lower lip is interrupted by a large gap. The barbels are laterally compressed with foliate appendages, arranged in two pairs, originating midway or closer to the mouth than to the tip of the snout.[7]
However, during growth, the beluga sturgeons show evident morphologic changes:
- Juveniles are slender, and the head is quite narrow with a mouth ventrally placed but projecting upward. The snout is thin and pointed (almost half of the head), scutes are evident, back and flancs are dark grey or black and the belly is white.
- Adults are heavy-set, spindle-shaped, large and humpbacked. The head is massive with a very large protractile mouth that gradually moves in an almost frontal position during growth. The snout is quite short (one-third to one-quarter of the head), and scutes gradually undergo absorption and decrease in number with age. Colouring is blue-grey or dark brown, with silver or grey flancs and white belly. The dark dorsum contrasts strongly against the rest of the body;
- Very old specimens are stocky, with a large head and an enormous mouth.[7][8][9]
Size
Among all extant bony fishes, the beluga sturgeon rivals the
The largest accepted record is of a female taken in 1827 in the Volga estuary at 1,571 kg (3,463 lb) and 7.2 m (23 ft 7 in).[10][12] Another specimen reportedly weighed 1,220 kg (2,690 lb) and measured 6.1 m (20 ft 0 in) in length. Claims about greater length (10 m (32 ft 10 in), or even 12 m (39 ft 4 in)); and weight (2,000 kg (4,400 lb), 2,500 kg (5,500 lb), or even 3,000 kg (6,600 lb)) are disputed and unconfirmed; but they are not impossible.[13] Several other records of aged sturgeon exceed 5 m (16 ft 5 in).[10] Among sturgeons, only the closely related Kaluga (Huso dauricus) can attain similar size, with a maximum weight of 1,000 kg (2,200 lb).
Beluga of such great sizes are very old (continuing to grow throughout life) and have become increasingly rare in recent decades because of heavy fishing of the species. Today, mature belugas that are caught are generally 142–328 cm (4 ft 8 in – 10 ft 9 in) long and weigh 19–264 kg (42–582 lb). The female beluga is typically 20% larger than the male.[14] An exceptionally large beluga recently caught weighed 960 kg (2,120 lb) and measured 3.4 m (11 ft 2 in).[7]
Biology
Due to rampant overfishing, the average lifespan of beluga sturgeon is unknown, with no specimens living past their 56th year. However the species is reportedly quite long-lived, being capable of surviving over 100 years in the wild.[15]
Spawning
Like most sturgeons, the beluga is
Males attain sexual maturity at 12–16 years of age, whereas females do so at 16–22 years. They will spawn every four to seven years. At one time, beluga sturgeons could migrate up to 1,000 km (620 mi) upriver to spawn, but dams in almost every major tributary that they utilize have impeded historic spawning routes. The female lays her eggs on gravel from 4 to 40 m (13 to 131 ft) underwater. Upon hatching, the embryo are 11 to 14 mm (0.43 to 0.55 in) long, and 10–14 days later when they absorb their yolk sack, the length is 18 to 20 mm (0.71 to 0.79 in). Thereafter, the larvae usually subsist on benthic invertebrates, but when reaching at least 10 cm (3.9 in) in length, they will switch to a fish-based diet. While swimming back to the ocean, the young sturgeon may cover up to 60 km (37 mi) a day.[18][19]
Diet
Huso huso is a pelagic predator whose local distribution is not influenced by the nature of the substrates, unlike with most of the sturgeons that show demersal attitude.[7] The prey is sucked into the mouth opening extremely quickly.[1]
Juveniles feed on
The piscivorous diet of beluga sturgeon tends to change with age: in the Caspian Sea, it mainly consists of Clupeonella sp. for juveniles smaller than 40 cm, different species of Gobiidae for fish ranging between 40 and 280 cm and then mullets, Alosa sp. and other sturgeons for the largest.[21]
In brackish environments of the
Little is known about the diet of the extinct Adriatic population. It has been reported that in marine and brackish environments, adult Adriatic H. huso foraged primarily on molluscs (
Habitat
Beluga sturgeon are considered euryhaline, capable of moving freely between freshwater and estuaries, and thus can live in waters of varying saline content. Sturgeons are quite a durable species and can survive some of the most altered and polluted rivers in the world.[15]
Historically, beluga sturgeon were found in the Caspian Sea, Black Sea, Adriatic Sea, Sea of Azov, and all rivers interconnecting these waterways. Unfortunately, this range has been greatly reduced in modern times to the Caspian Sea, the Black Sea, and a few rivers such as the Danube, with attempts to reintroduce Belugas into various historic locations.[23]
Uses
Beluga caviar is considered a delicacy worldwide.[24] The flesh of the beluga is not particularly renowned, but it is a hearty white meat similar to that of swordfish. Beluga caviar has long been scarce and expensive and the fish's endangered status has made its caviar even more expensive throughout the world.
The beluga's
Status
The
Repopulation efforts
Since 2015, an official captive breeding scheme has been established in Italy, with beluga from the Azov Sea.[28] Then, after the building of a fish ladder on Isola Serafini dam, on 2019 hundreds of young microchipped beluga and 60 tagged subadults were released into the Po river, following EU Projects (Life Ticino Biosurce).[29] Since then, many H. huso were released in the Po river, attempting to resurrect the extinct Adriatic population.[30]
Management of sturgeon fisheries within the Caspian Sea began in the 1950s and while the initial regulations had honorable intentions, they achieved dwindling effects due to the ever present demand for the fish's caviar.[23] In July 2016, Sturgeon Aquafarms in Bascom, Florida became the first and only facility in the world to obtain a permit exemption for the sale of beluga sturgeon and its caviar in the U.S.[citation needed] Since 2017, the company has assisted in beluga sturgeon repopulation efforts across the world by providing over 160,000 fertilized eggs to the Caspian Sea region.[31]
Following a
Threats
The beluga sturgeon is confronted by several critical threats that imperil its existence. Illegal harvesting, habitat disruption through dam construction, and pollution are among the most pressing challenges faced by this magnificent species.[33]
Illegal harvesting and poaching
The beluga sturgeon faces a significant threat from illegal catches for its meat and caviar. The excessive harvesting and a sharp increase in poaching have removed the largest and most mature specimens from the population, almost eliminating natural reproduction. This exploitation has pushed the species to the brink of extinction.[33]
Habitat impoundment
The construction of dams, such as the Iron Gate in the Danube and the Volgograd Dam, has severely reduced the beluga sturgeon's available spawning grounds. These dams have blocked access to crucial river habitats, leading to a significant reduction in the species' ability to reproduce. Similar habitat loss has occurred in other rivers due to dam construction, greatly impacting the species' survival.[33]
Pollution
Pollution from various sources, including oil, industries, sewage, and agriculture, is a critical threat to the beluga sturgeon. The species' long lifespan makes it vulnerable to pesticide contamination, resulting in reduced reproductive success and other health issues. Pollution negatively affects the quality of the sturgeon's habitat, compounding the challenges faced by this endangered species. [33]
References
- S2CID 84869858.
- ^ . Retrieved 24 May 2023.
- ^ "Appendices | CITES". cites.org. Retrieved 14 January 2022.
- ^ Froese, R.; Pauly, D. (2017). "Acipenseridae". FishBase version (02/2017). Retrieved 18 May 2017.
- ^ "Acipenseridae" (PDF). Deeplyfish- fishes of the world. Retrieved 18 May 2017.
- ^ Huso huso. Fishbase.org. Accessed on 11 January 2008
- ^ a b c d e Vecsei, P., Sucui, R., & Peterson, D. (2002). Threatened fishes of the world: Huso huso (Linnaeus, 1758)(Acipenseridae). Environmental Biology of Fishes, 65(3), 363-365.
- ^ Tortonese E. (1970). Fauna d'Italia, X: Osteichthyes. Calderini, Bologna. pp. 75–85.
- ^ a b "Lo storione attilo o ladano o beluga, Huso huso (Linnaeus, 1758)".
- ^ ISBN 978-0-85112-235-9
- ^ Burton, M., & Burton, R. (2002) International Wildlife Encyclopedia: Index volume (Vol. 22). Marshall Cavendish.
- ^ Berg, Leo S, Freshwater fishes of the USSR and adjacent countries. Vol. 1 (1962). (Israel Program for Scientific Translations). Jerusalem
- ^ Balon, E.K. (1967). Evolution of the Danube ichthyofauna, its recent state and an attempt to predict further changes after the construction of the planned hydroelectric power-stations and diversion schemes. Biologicke prace 13: 1–121, 24 plates.
- ^ "Huso huso". caspianenvironment.org. 2011. Archived from the original on 21 July 2012.
- ^ a b Chakrabarty, Prosanta (2003). Fink, William (ed.). "Huso huso (Beluga)". Animal Diversity Web. Retrieved 24 May 2023.
- ^ Suciu, M; Paraschiv, M; Ene, C; Suciu, R (2005). "Downstream migration of young of the year beluga sturgeons (Huso huso) in the lower Danube River". Proceedings of the 5th International Symposium on Sturgeons, 9-13 May 2005. Ramsar, Iran: Blackwell. pp. 306–308.
- ^ Dalia Onara, Radu Suciu, Marian Paraschiv, Marian Iani, Daniela Holostenco, Elena Tafla (2011). "Contributions to Understanding the Spawning Ecology of Sturgeons in the Lower Danube River, Romania" (PDF). Danube Parks.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ a b c Pirogovskii, M.I., L.I. Sokolov & V.P. Vasil’ev. 1989. Huso huso (Linnaeus, 1758). pp. 295–344. In: J. Holcík (ed.) The Freshwater Fishes of Europe, Vol. I/II: General Introduction of Fishes, Acipenseriformes, AULA-Verlag, Wiesbaden
- ^ Hochleithner, M. & J. Gessner. (2001). The sturgeons and paddlefishes of the world. Aquatech Publications. 202 pp.
- ^ Khodorevskaya R.P., Polyaninova A.A., Geraskin P.P., Romanov, A.A. (1995). "A study on physiological and biochemical status of Beluga sturgeon, Huso huso (L.), and its feeding habits". Proc. Intern. Sturg. Symp. Moscow. VNIRO: 164–172.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ Filippov, G.M. (1976). "Some data on the biology of the beluga Huso huso from the south-eastern part of the Caspian sea". J. Ichthyol. 16 (4): 566–574.
- ^ Sokolov L.I., in Holcík J. (1989). Freshwater fishes of Europe (Vol I part II). General Introduction to Fishes and Acipenseriformes. Wiesbaden: Aula Verlag.
- ^ a b The Decline of the Beluga Sturgeon: A Case Study about Fisheries Management (PDF) Larissa J. Graham and Brian R. Murphy
- ^ "Beluga Caviar". Food Fancy. September 2012.
- ^ Reynolds, Francis J., ed. (1921). Collier's New Encyclopedia. New York: P. F. Collier & Son Company. .
- ^ a b "Thousands of Critically Endangered Beluga Sturgeon Released into the Danube". World Wildlife Fund. 29 June 2020. Retrieved 28 May 2022.
- Science Daily. 4 March 2008.
- ^ "Azioni preparatorie alla reintroduzione di Huso huso nel fiume Ticino (2015-2016)".
- ^ PARCO LOMBARDO DELLA VALLE DEL TICINO, Sviluppo sostenibile, tutela della biodiversità e dell’ambiente, qualità della vita (28 March 2019). "Huso Huso: riparte da Pavia il ripopolamento nel Ticino". ticinobiosource.it. PDF.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ "Nuova operazione di reinserimento di Huso huso nel fiume Ticino!".
- ^ "Sturgeon Aquafarms Aims To Sustainably Produce Caviar While Restoring Wild Sturgeon Populations". Forbes. 19 April 2019.
- ^ "WWF: Sturgeon poaching again on the rise in Romania, Ukraine". Romania Insider. 31 March 2021. Retrieved 28 May 2022.
- ^ a b c d "Redlist - Huso Huso (Beluga) threats to the species".
External links
- "Huso huso". Integrated Taxonomic Information System. Retrieved 24 January 2006.
- Annex II of the Convention on the Conservation of European Wildlife and Naturaabitats. Revised 1 March 2002.