Adriatic sturgeon
Acipenser naccarii | |
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Adriatic sturgeon with sea lampreys in the Aquarium Finisterrae, Spain | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Acipenseriformes |
Family: | Acipenseridae |
Genus: | Acipenser |
Species: | A. naccarii
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Binomial name | |
Acipenser naccarii Bonaparte 1836
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Synonyms[3][4] | |
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The Adriatic sturgeon (Acipenser naccarii) is a species of fish in the family
Description
The Adriatic sturgeon reaches a maximum length exceeding 2 m (6.6 ft); the published maximum weight was 25 kg (55 lb), but large wild fish recently caught were evidently exceeding 40 kg (88 lb).
Like other sturgeons it has an elongated body,
Adriatic sturgeon was reported as very similar to the critically endangered European sea sturgeon (
- shorter and stocky snout;
- darker back, brown;
- less and lesser scutes in the lateral series;
- larger mouth;
- barbels closer to the tip of the snout (in A. sturio they are closer to the mouth);
- the mouth ends just after the front end of the operculum (in A. sturio it ends in the middle of the operculum);
- smaller dimensions.
Distribution
The Adriatic sturgeon can be found in freshwater and marine environments, including estuaries and brackish water. Historically it was to be found in the Adriatic Sea and the rivers flowing into it on either side. In 1932 its range in the sea was reported to be from Venice and Trieste to Greece and Corfu. It used to be present in the rivers Adige, Brenta, Bacchiglione, Piave, Livenza and Tagliamento. In the Po and its tributaries, it used to be present as far upstream as Turin, and it was reported numerous in the Ticino and Adda rivers. It traditionally occurred along the Albanian coasts, and in the rivers of Slovenia, Croatia, Bosnia-Herzegovina and Montenegro, including Lake Skadar.[citation needed]
Biology
Once considered an
Reproduction
Adriatic sturgeons are slow-growing, long-lived fish; wild males are sexually mature at 7–11 years old (about 80 cm, or 2.6 ft, long), and females at 12–14 years old (at least 1 m, or 3.3 ft, long). Females ovulate every 2–4 years.[13]
During spring months mature fish migrate to the upper part of the rivers, then they lay eggs from April to June[14] in deep and oxygenated waters, on gravelly substrates at a depth of 2–10 m (6.6–32.8 ft),[15] with a current velocity of 0.8 m/s at least.[16] Water turbulence is very important for the reproductive success of sturgeons, since it avoids egg stress, aggregation of the eggs, anoxia, parasites, and predators.[17]
The eggs adhere at the substrate and hatch after about a week, fry are about 8–10 mm (0.31–0.39 in) long with pelagic attitude like other sturgeons, then after ten days they begin to be demersal.[8]
Diet
Adriatic sturgeons tend toward an opportunistic feeding, swallowing substrate together with prey and organic matter, including small decaying carrions. In the rivers they mainly eat
Ecology
The typical habitat of A. naccarii are large, deep rivers with strong current, which flows in the Adriatic sea, mainly in its north-western portion. In the sea it lives in lagoons and close to the estuaries, mainly on muddy and sandy substrates, at a depth of 10–40 m (33–131 ft).
Juveniles of Adriatic sturgeon can adapt at a salinity of 20–30‰,[20] as opposed to other species of sturgeons.[21] However, despite some A. naccarii have been captured in the Adriatic Sea, it has been shown that this sturgeon tolerates with difficulty high salinity for extended periods, spending in marine environments short periods for foraging activities.[22] The low tolerance to full-strength salt water constitutes a strong constraint to migration across Adriatic Sea where the salt contents can reach up to 37‰.[23] Furthermore, it has been shown, tracking the movements of tagged fish in some cold and oxygenated rivers of northern Italy (Piave, Sile, Livenza), that A. naccarii regularly moves to areas where the salt intrusion from the sea involves an electrical conductivity of 1000–4000 μS in the water (about 0.6–2.5‰ salinity at 18 °C), on equal terms of other environmental variables.[24]
Genetic
A study on genetic variability of Acipenser naccarii, based on mitochondrial and nuclear DNA, showed that sturgeons of the Po basin are genetically distinguished from those of the Buna (Bojana) basin. So, the introduction of sturgeons of the Po in the Buna river would jeopardize the genetic differences between both populations and should thus be avoided[23] (if the Buna population is still existing).
Status
Official status
The
It has been reported by researchers that, despite the release of captive-bred fish, no signs of spawning have been observed in the wild;[1] however, considering that Adriatic sturgeon needs at least twelve years to attain sexual maturity and matures gonads in alternate years, and considering the release of captive small fish started in 2004, it was probably premature to look for wild fingerlings at the time of the publication of the report (2011).
About the southwestern population, it was reported that Adriatic sturgeon was seen for the last time in Greece in 1977, and in Albania in 1997 in the Buna River, but has not been seen there since;[1] however, in 2003 a study published genetic data of several specimens especially caught in Buna river, below the confluence with Lake Skadar.[23]
Present status (2020)
In the recent past catfish anglers caught, filmed and released mature specimens of Adriatic sturgeon in the Po and other rivers, also very large, old fish (for example, [1], [2],[3]).[27] After the building of a fish ladder on Isola Serafini dam, on 2018 a project GRAIA (Gestione Ricerca Ambientale Ittica Acque) started and a cam is now monitoring continuously the passage of fish through the mentioned ladder. Among millions of fish, mature specimens of Adriatic sturgeon were filmed.[citation needed]
The capture of juveniles without microchips, smaller than those released into the wild by researchers and authorities, is an indication that Adriatic sturgeon naturally spawned in Italian rivers.[28] Molecular analyses showed that, among those fish, some were not related with the captive broodstock,[8] so it seems that a wild broodstock still exists.
Threats
The main threat that Adriatic sturgeons face is
Another important problem is pollution of rivers by industrial effluent, agricultural runoff and civil wastewaters.[citation needed]
During the XX century, overfishing on adults and above all immature sturgeons was another important cause of the decline of the wild stock of A. naccarii. Despite it is now a protected species, illegal fishing by poachers is presently one of the main threat in the Po basin (for example, [4],[5]), particularly harmful when smaller fish are taken before they have reached maturity and reproduced at least once. Illegal capture with giant lift nets placed close to the estuaries can be a big threat, as well as commercial fishing in the sea and lagoons.[citation needed]
Predation by cormorant on juveniles is another important problem: Italian wintering populations of these birds are extremely numerous and increasing every year,[30] so many of them are moving to rivers and lakes, due to numerical saturation of the coastal areas.[31]
Adriatic sturgeons also face competition from the wels catfish, which has expanded its range into Western Europe; however, wels catfish cohabits with many species of sturgeon in its native range. It has been supposed that, as they have become fewer in number, they could be affected by the Allee effect,[1] which postulates that a fish's growth rate is reduced at low population densities; however, any study was published about Allee effect on A. naccarii.
References
- ^ .
- ^ "Appendices | CITES". cites.org. Retrieved 14 January 2022.
- ^ Froese, R.; Pauly, D. (2017). "Acipenseridae". FishBase version (02/2017). Retrieved 18 May 2017.
- PMID 25543675.
- ^ Tortonese E. (1970). Fauna d'Italia, X: Osteichthyes. Calderini, Bologna. pp. 75–85.
- ^ "Acipenser naccarii Bonaparte, 1836: Adriatic sturgeon". FishBase. Retrieved 6 February 2016.
- ISBN 978-3-642-20611-5.
- ^ a b c d Various Authors (2010). Action Plan dello storione cobice Acipenser naccarii (Bonaparte 1834-1841). EU Life Project 04NAT/IT/000126.
- ^ Marconato E., Maio G., Busatto T., Salviati S. (2006). "Il progetto di recupero dello storione cobice (Acipenser naccarii) nelle acque del F. Piave". Biologia Ambientale. 20 (1): 25–32.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ Nardi, P.A. (1982). I pesci del Parco [della Valle] del Ticino. Fabbri Ed.
- ^ Bernini F., Nardi P.A. (1992). "Gli storioni: riflessioni e proposte di tutela". Pianura. 4 (1): 11–18.
- ^ Bernini F., Nardi P.A. (1990). "Accrescimento di A. naccarii (Osteichthyes. Acipenseridae) nel tratto pavese dei fiumi Po e Ticino". Boll. Mus. Reg. Sci. Nat. Torino. 8 (1): 159–172.
- ^ Arlati G. (1996). "Storioni in Lombardia". Lombardia Verde (2): 6–8.
- ^ Rossi R., Grandi G., Trisolini R., Franzoi P., Carrieri A., Sayyaf Dezfuli B., Vecchietti E. (1991). "Osservazioni sulla biologia e la pesca dello storione cobice Acipenser naccarii nella parte terminale del fiume Po". Atti della Società di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 132 (10): 121–142.
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: CS1 maint: multiple names: authors list (link) - ^ Tortonese, E. (1989). Acipenser naccarii. General introduction to fishes. Acipenseriformes. In: The freshwater fishes of Europe. 1 (2): Ed. J. Holcik. AULA Verlag, Weisbaden. pp. 285–293.
{{cite book}}
: CS1 maint: location (link) - S2CID 43668588.
- S2CID 41960824.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ Bernini F., Nardi P.A. (1990). "Regime alimentare di A. naccarii (Osteichthyes. Acipenseridae) nel tratto pavese dei fiumi Po e Ticino". Boll. Mus. Reg. Sci. Nat. Torino. 8 (2): 429–439.
- ^ D'Ancona, U. (1989). Contributo alla biologia degli storioni nelle acque italiane. Roma: Libreria dello Stato, Ministero dell’economia nazionale, direzione generale dell'agricoltura, Divisione V. Osservatorio di pesca di Fiumicino.
- hdl:2108/186795.)
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: CS1 maint: multiple names: authors list (link - S2CID 41234013.)
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: CS1 maint: multiple names: authors list (link - doi:10.1111/j.1439-0426.1999.tb00208.x.)
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: CS1 maint: multiple names: authors list (link - ^ S2CID 10305914.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - ^ a b Various Authors (2006). Action Plan per la gestione di Acipenser naccarii, dei suoi siti riproduttivi e della pesca. EU Life Project 03NAT/IT/000113, Parco Ticino, Regione Lombardia.
- ISBN 978-1-4816-3075-7.
- PMID 21483472.
- ^ Grisendi, Y. (2 November 2015). "Storione gigante pescato nel Po" (in Italian). La Repubblica. Retrieved 5 November 2015.
- ^ F.I.P.S.A.S. - Comitato regionale veneto, Regione Veneto (2017). Progetto di recupero della specie endemica Acipenser naccarii (storione cobice) nei corsi d'acqua della regione Veneto - relazione conclusiva (PDF). Regione Veneto.
- doi:10.1016/S1095-6433(98)10134-4.)
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: CS1 maint: multiple names: authors list (link - ^ "Natural Parks of Piemonte Region – Official website".
- ^ Baccetti N., Giunti M. (2002). "Dinamica di insediamento e struttura della popolazione di Cormorano (Phalacrocorax carbo) svernante in Italia". I.N.F.S., Relazione Finale del Progetto di Ricerca 4C-155, Contributi Ricerca Scientifica L. 41/82, IV Piano Triennale, Tematica C.1.4.