European houses

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European houses
Hausen (Huso huso L.) editDOB.JPG

European Hausen ( Huso huso )

Systematics
Class : Ray fins (Actinopterygii)
Subclass : Cartilage organoids (chondrostei)
Order : Sturgeon (Acipenseriformes)
Family : Sturgeon (Acipenseridae)
Genre : Hausen ( Huso )
Type : European houses
Scientific name
Huso huso
( Linnaeus , 1758)

The European Hausen or Beluga sturgeon ( Huso huso ) is the largest species of fish in the family of sturgeons (Acipenseridae) and is considered to be one of the largest bony fish . It occurs in the Black and Caspian Seas and in the adjacent large rivers and was formerly also found in the northern Adriatic . The Hausen is traditionally caught primarily for caviar production, but also as edible fish . Due to overfishing and the loss of suitable spawning grounds, the species is now considered threatened with extinction.

features

4.17 meters long and one tonne heavily prepared houses in the National Museum of Kazan

The Hausen has the typical elongated shape of the sturgeon with five rows of bone shields and heterocerker caudal fin . Compared to other sturgeons, the body is bulky and stocky. The animals are dark to blue-gray with a lighter belly and bone shields. The snout is relatively short and broadly rounded in animals from the Black Sea and elongated longer in animals from the Caspian Sea . As with the Kaluga house ( Huso dauricus ), the mouth is crescent-shaped and so wide that it extends to the edge of the snout. In contrast to that of the sturgeon ( Acipenser ), it opens towards the front and the four barbels sitting in front of it are flattened and fringed on the sides. The gill membranes on both sides are connected and free on the abdomen. The gill trap has 17 to 36 thorns. In contrast to Kaluga-Hausen, the highest point of the back is behind the first back shield. The 9 to 17 dorsal shields are rounded, behind the 48 to 81-rayed dorsal fin there are no shields. The 28 to 60 side shields are separate and easily visible or almost absorbed by the skin. The same applies to the 7 to 14 abdominal shields that can be clearly seen in young animals. The skin between the shields is largely bare. Between the anus and the 22- to 41-rayed anal fin are 0 to 3 shields.

size

The length of sexually mature houses is usually 185 to 250 centimeters. The animals can, however, become significantly larger, although the length specifications vary from author to author. Usually five to six meters in length and one tonne in weight are given as the maximum. FishBase states the maximum documented weight is 2072 kilograms. From the 19th century there are reports of even larger animals with a length of eight meters and a weight of over three tons, which are now considered questionable.

Occurrence

The original distribution area of ​​the European house comprised the Black Sea with the Azov Sea , the Caspian Sea and the Adriatic Sea as well as their larger tributaries. The species has disappeared from the Adriatic and the Sea of ​​Azov. In the Black Sea the last stocks migrate to spawn in the Danube , in the Caspian Sea in the Urals . The stocks in the Volga are preserved through stocking. Due to the longevity of the animals, individual individuals can still be found in areas where reproduction is no longer possible today.

In the Danube, the species used to occur as far as Austria, and more rarely even to Germany, making it the anadromous migratory fish with the longest migratory distance (maximum 2320 kilometers) among the sturgeons . The most important spawning grounds were in the area of ​​today's Hungarian / Slovakian border. The entire upper distribution area was cut off by the construction of the dams Kraftwerk Eisernes Tor 1 and Kraftwerk Eisernes Tor 2 in 1972 and 1984, respectively, which are not passable for the species. Spawning areas in the Danube were registered in 2003 in the area of ​​the Bulgarian-Romanian border , river kilometers 755 to 840, between Lom and Arjar , for example . Spawning grounds were located in water depths between 9 and 22 meters on gravel or coarse sand in areas with a clear current, often in the area of ​​river islands.

Way of life

In contrast to most other sturgeons, Hausen are active hunters who hunt in the open water at depths of over 170 meters and mainly feed on other fish, with herring- like species such as the European anchovy in the Black Sea and Clupeonella and Alosa species in the Caspian Sea as well as gobies make up the main prey. Mollusks and various crustaceans are also eaten, and there are even individual reports of the capture of water birds and seals.

The later Emperor Sigismund with princes in company on the Waag , a left tributary of the Danube in Slovakia . Two "husen" (houses) can be seen under the ship. (From Eberhard Windeck : Das Buch von Kaiser, 15th century)

The animals migrate into the rivers to spawn . In the Danube , the Hausen originally rose into German territory. The animals spawn every two to four years. Hikes can take place all year round, with the main hiking season being from October to November and February and March. The animals that migrate in autumn overwinter in deep places in the river and spawn together with those that migrate in spring from April to June. The up to 7 million eggs per female are deposited in deep places with stony ground and strong currents. The young hatch after 8 to 10 days and allow themselves to be driven downstream by the current, whereby up to 60 km can be covered per day. After they have been feeding on the yolk for seven to eight days , they begin to prey on fish larvae from a length of around three centimeters. The young animals spend the summer mainly in the shallow river water and reach the sea in the first year, where they stay until they reach sexual maturity . This is achieved by males between the ages of 10 and 16, and females between the ages of 14 and 20. The age of four meters long animals was determined to be around 100 years.

use

The European Hausen is mainly fished for the eggs used as caviar , which are traded as beluga caviar after the Russian name of the species. For this purpose, the females are caught on the spawning migration in the area of ​​the river mouths. Beluga caviar is considered to be of particularly high quality, so that in 2009 one kilogram had a commercial value of around 8,000 US dollars. In addition, the meat from fish caught mainly at sea is used. Because of the esteemed eggs, hybrids of female Hausen and male sterlets ( Acipenser ruthenus ) are also bred, which are called "best".

In old Fulda monastery documents , the "Husen" from the upper Danube is mentioned early on as an annual "offering" to the Fulda Benedictine monastery to cover the livelihood of around 400 monks , for example by Passau Bishop Vivilo (around 739 to around 744/745) and the Regensburg Bishop Gaubald (739–761). Even later, until the 17th century, numerous Hausen fish donations were made to the Fulda monastery . The "Hausen" was once at home in the Altmühl , too . Bishop Megingoz von Eichstätt (991-1015) sent Bishop Heinrich I von Würzburg (995 / 996-1018) house fish from the Altmühl as a gift in return for good wine .

Traditionally, the swim bladder of the house, the isinglass , was also used as the starting material for glue . The isinglass glue was considered a particularly high-quality animal glue and was used by winemakers, silk weavers , hairdressers , celebrity chefs and medical professionals.

Filigree reliefs were also made from isinglass in religious folk art, the breath pictures or isinglass pictures .

threat

The European Hausen is in the red list of the IUCN "threatened with extinction" as performed ( "critically endangered") and in the Annex II Bonn Convention listed. The stock of the Mediterranean Sea also enjoys protection according to Appendix II of the Bern Convention , which forbids the deliberate catching and removal of eggs. The catch numbers indicate that populations have decreased by about 90% over the past three generations. Due to the high value as food fish and caviar supplier, the stock of the house in various waters is supported by the stocking of young fish. In the Sea of ​​Azov and the Volga, the species probably only exists because of this population.

The main reasons for the collapse of the Hausen populations are the losses through targeted fishing at sea and in the river mouths as well as through animals killed as bycatch and the loss of suitable spawning grounds through river barriers. The construction of the Volgograd reservoir destroyed an estimated 88 to 100% of the spawning grounds in the Volga or made them inaccessible to the animals. In addition to these main hazards, pesticide poisoning and the avenue effect are also seen as threats to the species.

literature

Individual evidence

  1. ^ A b c Minister of Supply and Services Canada (Ed.): CITES Identification Guide - Sturgeons and Paddlefish: Guide to the Identification of Sturgeon and Paddlefish Species Controlled under the Convention on International Trade in Endangered Species of Wild Fauna and Flora . Wildlife Enforcement and Intelligence Division, Environment Canada, 2001, ISBN 0-660-61641-6 (English, French, Spanish, full text (PDF; English, French, Spanish; 10.9 MB)).
  2. ↑ a b c d e Roland Gerstmeier, Thomas Romig: The freshwater fish of Europe for nature lovers and anglers . 2nd Edition. Franckh-Kosmos, Stuttgart 2003, ISBN 3-440-09483-9 , pp. 143-144 .
  3. ↑ a b c d e European House on Fishbase.org (English)
  4. ↑ a b c d e f Maurice Kottelat, Jörg Freyhof: Handbook of European Freshwater Fishes . Cornol, JU 2007, ISBN 978-2-8399-0298-4 , pp. 420, 422 .
  5. ↑ Milen Vassilev (2003): Spawning Sites of Beluga Sturgeon (Huso huso L.) located along the Bulgarian-Romanian Danube River stretch. Acta Zoologica Bulgarica 55 (2): 91-94.
  6. ↑ a b Huso huso in the endangered Red List species the IUCN 2009. Posted by: Sturgeon Specialist Group, 2009. Accessed April 22 of 2010.
  7. ↑ Michael Mott : A giant fish for Bonifatius / A contribution to the Fulda monastery history, in: "Buchenblätter" Fuldaer Zeitung , 64th year, No. 12, May 28, 1991, p. 45 f.
  8. ^ Anna Bartl: The Liber illuministarum from Kloster Tegernsee: Edition, translation and commentary of the art-technological recipes . Steiner, Stuttgart 2005, ISBN 978-3-515-08472-7 , pp. 699 .
  9. ↑ Hans Gärtner: The good child. Diligent picture. An almost forgotten piece of school culture. , Poppe Verlag Windberg , 2014, ISBN 978-3-932931-84-0 , p. 88.
  10. ↑ Museum für Österreichische Volkskunde ( Memento of the original from October 23, 2013 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.volkskundemuseum.at
  11. ↑ Fish in Appendix II of the Bern Convention (accessed April 23, 2010)

Web links

Commons : Europäische Hausen ( Huso huso )  - Collection of images, videos and audio files