sturgeon

 

primitive fish of the northern regions of Europe, Asia, and North America. Unlike evolutionarily advanced fishes, it has a fine-grained hide, with very reduced scalation, a mostly cartilaginous skeleton, upturned tail fins, and a mouth set well back on the underside of the head. It also has widely separated rows of heavy guard scales, four barbels or feelers that hang below the head and help to locate food, and a gas bladder from which isinglass is made. Sturgeons feed by sucking in their food—e.g., crayfish, snails, larvae, and small fishes—from the water bottom through their small, toothless, fleshy-lipped mouths.

Some species are marine, e.g., the Atlantic sturgeon Acipenser oxyrhyncus; some ascend rivers to spawn; and some (the largest of inland fish) are found in landlocked waters. The largest species is the Russian sturgeon, or beluga (A. huso), of the Caspian and Black seas; it reaches a length of 13 ft (396 cm) and a weight of up to a ton (900 kg). The Pacific sturgeon (A. transmontanus) may weigh over half a ton (450 kg) and attain a length of 12 ft (366 cm). The green sturgeon is a smaller Pacific variety, and the common sturgeon is found in coastal waters and rivers of Europe and E North America. Other American species are the rock, or lake, sturgeon (A. fulvescens) of the Great Lakes and the Mississippi valley and the shovel-nosed sturgeon, or hackleback (Scaphirhynchus platorynchus; 3 ft/91 cm), also of the Mississippi valley.

Smoked sturgeon is considered a delicacy in many areas, and sturgeon eggs are the source of the better grades of caviar, sometimes in combination with eggs of the paddlefish, a close relative. Russia, Iran, and other countries surrounding the Caspian Sea have undertaken conservation measures, including aquaculture and setting catch quotas, to save the threatened Russian sturgeon from extinction, but declines in Eurasian species of sturgeon led to a suspension of the international trade in wild caviar from the region during 2006–7.

Sturgeons are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Acipenseriformes, family Acipenseridae.

Sturgeon
Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Acipenseriformes Family: Acipenseridae Genus: Acipenser Linnaeus, 1758
Species
See text.

Sturgeon is a term for a genus of fish (Acipenser) of which 26 species are known. One of the oldest genera of fish in existence, they are native to European, Asian, and North American waters. Sturgeons ranging from 7–12 feet in length are by no means scarce, and some species grow up to 14 feet. Sturgeons are polyploid; some species have 4, 8, or 16 sets of chromosomes.^[1]

Sturgeon are bottom-feeders. With their projecting wedgeshaped snout they stir up the soft bottom, and by means of their sensitive barbels detect shells, crustaceans and small fish, on which they feed. Having no teeth, they are unable to seize larger prey.

Only a few of the species are exclusively confined to fresh water. Sturgeon are confined to the Northern Hemisphere and do not inhabit tropical regions.

Uses

In Russia, sturgeon fisheries are of immense value. Early in summer the fish migrate into the rivers or towards the shores of freshwater lakes in large shoals for breeding purposes. The ova are very small, and so numerous that one female has been calculated to produce about three million in one season. The ova of some species have been observed to hatch within very few days after exclusion. In Sturgeons that have attained maturity their growth appears to be much slower, although continuing for many years. Frederick the Great placed a number of them in the Garder See Lake in Pomerania about 1780; some of these were found to be still alive in 1866.^{[citation needed]} Professor von Baer also states, as the result of direct observations made in Russia, that the Hausen (Acipenser huso) attains an age of 100 years, but can live over 210 years.^{[citation needed]}

In countries like England, where few sturgeons are caught, sturgeon is included as a royal fish in an act of King Edward II, although it probably only rarely graces the royal table of the present period, or even that of the lord mayor of London, who can claim all sturgeons caught in the Thames above London Bridge. Where sturgeons are caught in large quantities, as on the rivers of southern Russia and on the great lakes of North America, their flesh is dried, smoked or salted. The ovaries, which are of large size, are prepared for caviar, for this purpose they are beaten with switches, and then pressed through sieves, leaving the membranous and fibrous tissues in the sieve, whilst the eggs are collected in a tub. The quantity of salt added to them before they are finally packed varies with the season, scarcely any being used at the beginning of winter. Finally, one of the best sorts of isinglass is manufactured from the airbladder. After it has been carefully removed from the body, it is washed in hot water, and cut open in its whole length, to separate the inner membrane, which has a soft consistency, and contains 70% of glutin.

Sturgeon (and, therefore also the caviar trade) are under severe threat from overfishing, poaching and water pollution.^[2]

Species

The twenty-six species of sturgeons (Acipenser and Huso) are nearly equally divided between the Old and New Worlds. Most are now considered to be critically endangered, endangered or vulnerable. ^[3] The more important are the following (from 1911 Encyclopædia Britannica):

• The Common sturgeon (Acipenser sturio), also known as the European or Baltic sturgeon occurs on all the coasts of Europe, but is absent in the Black Sea. Almost all the British specimens of sturgeon belong to this species; it crosses the Atlantic and is sometimes found on the coasts of North America. It reaches 12 ft (4 m) long, but is always caught singly or in pairs, so that it cannot be regarded as a fish of commercial importance. The form of its snout varies with age (as in the other species), being much more blunt and abbreviated in old than in young examples. There are 11–13 bony shields along the back and 29–31 along the side of the body. The European or Atlantic sturgeon is now mostly gone from overfishing.

• The Russian sturgeon, Acipenser gueldenstaedtii is one of the most valuable species of the rivers of Russia, where it is known under the name Osétr (Осётр) or Ossetra; it is said to inhabit the Siberian rivers also, and to range eastwards as far as Lake Baikal. It was so abundant in the rivers of the Black and Caspian seas that more than one-fourth of the caviars and isinglass manufactured in Iran and Russia was derived from this species. However, due to poaching and overfishing it is now a threatened species.

• The Starry sturgeon, Acipenser stellatus, the "Sevruga" (Севрюга) of the Russians, occurs likewise in great abundance in the rivers of the Black Sea and of the Sea of Azov. It has a remarkably long and pointed snout, like the sterlet (below), but simple barbels without fringes. Though growing only to about half the size of the preceding species, it is of no less value, its flesh being more highly esteemed, and its caviar and isinglass fetching a higher price. In 1850 it was reported that more than a million of this sturgeon are caught annually.

• The Lake sturgeon, Acipenser rubicundus (today: Acipenser fulvescens), with which, in the opinion of American ichthyologists, the sea-going sturgeon of the rivers of eastern North America, Acipenser maculosus?, is identical, has of late years been made the object of a large and profitable industry at various places on Lake Michigan and Lake Erie; the flesh is smoked after being cut into strips and after a slight pickling in brine; the thin portions and offal are boiled down for oil; nearly all the caviar is shipped to Europe. One firm alone uses from ten thousand to eighteen thousand sturgeons a year, averaging 50 lb (23 kg) each. The largest lake sturgeon recorded in the Great Lakes was caught in Lake Superior in the 1920s by Frank Lapoint, measuring 2.25 m (7.5 ft) and weighing 140 kg (310 lb).^[4] The sturgeons of the lakes are unable to migrate to the sea, whilst those below Niagara Falls are great wanderers; and it is quite possible that a specimen of this species said to have been obtained from the Firth of Tay was really captured on the coast of Scotland.

• The beluga sturgeon, Huso huso, the "Hausen" of Germany, is recognized by the absence of osseous scutes on the snout and by its flattened, tape-like barbels. It is one of the largest species, reaching in exceptional cases enormous lengths of more than 5m and a weight of more than 2000 lb (900 kg). It inhabits the Caspian and Black seas, and the Sea of Azov, whence in former years large shoals of the fish entered the large rivers of Russia and the Danube. But its numbers have been much thinned, and specimens of 1200 lb (540 kg) in weight have now become scarce. Its flesh, caviar and air-bladder are of a greater value than those of the smaller, more common, kinds.

• The sterlet, Acipenser ruthenus, is one of the smaller species, which likewise inhabits both the Black and Caspian seas, and ascends rivers to a greater distance from the sea than any of the other sturgeons; thus, for instance, it is not uncommon in the Danube at Vienna, but specimens have been caught as high up as Ratisbon and Ulm. It is more abundant in the rivers of Russia, where it is held in high esteem on account of its excellent flesh, contributing also to the best kinds of caviar and isinglass. As early as the 18th century attempts were made to introduce this valuable fish into the Province of Prussia and Sweden, but without success. The sterlet is distinguished from the other European species by its long and narrow snout and fringed barbels. It rarely exceeds a length of 3 ft (1 m).

Other species in the genus Acipenser include:

• Acipenser baerii
  • Siberian sturgeon, Acipenser baerii baerii
  • Baikal sturgeon, Acipenser baerii baicalensis
• Shortnose sturgeon, Acipenser brevirostrum[1]
• Yangtze sturgeon (or Dabry's sturgeon), Acipenser dabryanus
• Green sturgeon, Acipenser medirostris
• Sakhalin sturgeon, Acipenser mikadoi
• Japanese sturgeon, Acipenser multiscutatus
• Adriatic sturgeon, Acipenser naccarii
• Fringebarbel sturgeon (or bastard sturgeon, ship sturgeon, spiny sturgeon, thorn sturgeon), Acipenser nudiventris
• Acipenser oxyrinchus
  • Gulf sturgeon, Acipenser oxyrinchus desotoi
  • Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus
• Persian sturgeon, Acipenser persicus
• Amur sturgeon, Acipenser schrenckii
• Chinese sturgeon, Acipenser sinensis
• White Sturgeon, Acipenser transmontanus

The family Acipenseridae includes three other genera, Scaphirhynchus, the shovel-headed or shovel-nosed sturgeons, distinguished by the long, broad and flat snout, the suppression of the spiracles, and the union of the longitudinal rows of scales posteriorly. All the species are confined to fresh water. One of them is rare in the Mississippi and other rivers of North America, the other three occur in the larger rivers of eastern Asia; the beluga sturgeons of genus Huso, and the false shovel-headed sturgeons, of Scaphirhynchus sister genus, Pseudoscaphirhyncus, and are confined to Northeastern Asia.

References in popular culture

• In the plot of Gordon Korman's MacDonald Hall books (especially in the third book, Beware the Fish) there are many references to this kind of fish: the headmaster of the school is called Mr. Sturgeon, and is nicknamed The Fish.

• American funk-rock band Primus mention sturgeons in their songs entitled The Ol' Diamondback Sturgeon (from the album Pork Soda) and Fish On (from the album Sailing the Seas of Cheese). Les Claypool, bass player and frontman of Primus, is an avid fisherman and sings about catching a "hundred-pound sturgeon on twenty-pound test" in San Pablo Bay in Northern California. A fictionalized account of a fishing trip aimed at catching sturgeon is chronicled in his book South of the Pumphouse.

• A sturgeon crashes on the Simpsons' car hood in "The Great Money Caper", triggering the events of the episode.

• In the children's comedy book Captain Underpants, the back of the cover page displays the "Sturgeon General's Warning" that the book contains crude content.

• Sturgeons have been cited as possible explanations for film of Loch Ness Monster-esque creatures, as their long length and slow movement could make a close-up shot of a sturgeon swimming past appear to be a very long fish.

See also

• Teleostei
• Volga Delta - the largest sturgeon breeding ground in the world
• World Sturgeon Conservation Society
• Wolf River-- the sturgeon guard
• FishBase info on Acipenser

References

1. ^ Anderson, Rachel (2004). Shortnose Sturgeon. McGill University. Retrieved on 2007-08-23.
2. ^ Clover, Charles. 2004. The End of the Line: How overfishing is changing the world and what we eat. Ebury Press, London. ISBN 0-09-189780-7
3. ^ World Sturgeon Conservation Society website
4. ^ Chisholm, B. & Gutsche, A., Superior: Under the Shadow of the Gods, Lynx Images, 1998, p. 29

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

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