STURGEON (Acipenser)  , the name given to a small group of fishes, of which some twenty different species are known, from European, Asiatic and North American rivers . The distinguishing characters of this group, as well as its position in the system, are dealt with in the article TELEOSTOMES . They pass a great part of the year in the sea, but periodically ascend large rivers, some in spring to deposit their spawn, others later in the season for some purpose unknown; only a few of the species are exclusively confined to fresh water . None occur in the tropics or in the southern hemisphere . Sturgeons are found in the greatest abundance in the rivers of southern Russia, more than ten thousand fish being sometimes caught at a singlefishing-station in the fortnight during which the up-stream migration lasts . They occur in less abundance in the fresh waters of North America, where the majority are caught in shallow portions of the shores of the great lakes . In Russia the 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 millions in one season . The ova of some species have been observed to hatch within a very few days after exclusion . Probably the growth of the young is very rapid, but we do not know how long the fry remain in fresh water before their first migration to the sea . After they 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 GOrland Lake in Pomerania about 178o; some of these were found to be still alive in 1866 . Professor von Baer also states, as the result of direct observations made in Russia, that the Hansen (Acipenser huso) attains to an age of from 200 to 300 years . Sturgeons ranging from 8 to 11 ft. in length are by no means scarce, and some species grow to a much larger size . Sturgeons are ground-feeders . With their projecting wedge-shaped snout they stir up the soft bottom, and by means of their sensitive barbels detect shells, crustaceans and small fishes, on which they feed . Being destitute of teeth, they are unable to seize larger prey . In countries like England, where few sturgeons are caught, the fish is consumed fresh, the flesh being firmer than that of ordinary fishes, well flavoured, though somewhat oily . The sturgeon is included as a royal fish in an act of King Edward II., although it probably but 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 caviare; 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 air-bladder .

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 76% of glutin . The twenty species of sturgeons (Acipenser) are nearly equally divided between the Old and New Worlds . The more important are the following:- 1 . The common sturgeon of Europe (Acipenser sturio) 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 not rare on the coasts of North America . It reaches a large size (a length of 12 ft.), 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 . 2 . Acipenser giildenstddtii is one of the most valuable species of the rivers of Russia, where it is known under the name " Ossetr " ; it is said to inhabit the Siberian rivers also, and to range eastwards as far as Lake Baikal . It attains to the same large size as the common sturgeon, and is so abundant in the rivers of the Black and Caspian seas that more than one-fourth of the caviare and isinglass manufactured in Russia is derived from this species . 3 .

Acipenser stellatus, the " Seuruga " of the' Russians, occurs likewise in great abundance in the rivers of the Black Sea and of the Sea of Azoff . It has a remarkably long and pointed snout, like the sterlet, 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 caviare and isinglass fetching a higher price . In 1850 it was reported that more than a million of this sturgeon are caught annually . 4 . The sturgeon of the great lakes of North America, Acipenser rubicundus, with which, in the opinion of Americah 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 Lakes Michigan and 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 caviare is shipped to Europe . One firm alone uses from ten to eighteen thousand sturgeons a year, averaging 50 lb each . The sturgeons of the lakes are unable to migrate to the sea, whilst those below the Falls of Niagara 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 . 5 . Acipenser 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 the enormous length of 24 ft. and a weight of 2000 lb . It inhabits the Caspian and Black seas, and the Sea of Azoff, 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 in weight have now become scarce . Its flesh, caviare and air-bladder are of less value than those of the smaller kinds . 6 . The sterlet (Acipenser ruthenus) is one of the smaller species, which likewise inhabits both the Black and Caspian seas, arid 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 caviare and isinglass . As early as the 18th century attempts were made to introduce this valuable fish into 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 it . The family Acipenseridae includes one other genus, Scaphirhynchus, the shovel-head or shovel-nosed sturgeon, 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 common in the Mississippi and other rivers of North America, the other three occur in the larger rivers of eastern Asia .