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The True Sturgeons family species, their habitats, characteristics, fishing methods.
Sturgeons, the survivors from the age of dinosaurs, in the early Jurassic period, are primitive fishes with rows of bony, armor-like plates on their sides and a skeleton composed mostly of cartilage rather than bones. They are a very old fish family whose ancestors could already be found in the Jurassic period, approximately 200 million years ago, making them among the most ancient of actinopterygian fishes. Their tail is heterocercal, similar to the tail of the shark and some other primitive fishes, the backbone extending into the larger, upper lobe of the tail. Four barbels hang under the sturgeon's long, flattened snout in front of the mouth. Sturgeons are bottom feeders, their sensory barbels being used to detect food and their protruded, tube-like mouth, to suck in bottom-dwelling plants and animals uncovered as they move along the mud.
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Sturgeon are large, primitive, bottom dwelling, and long-lived fish of the Acipenseridae family, one of the oldest families of bony fish in existence. Sturgeon includes over 20 species commonly referred to as sturgeon and several closely related species Sterlet, Kaluga and Beluga Sturgeon. Collectively, the family is also known as the True Sturgeons. Sturgeon is sometimes used more exclusively to refer to the species in the two best-known genera’s Acipenser and Huso. The best-known representative is Beluga - the largest freshwater fish and a source of most of European caviar.
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Sturgeon are native and widely distributed from subtropical, temperate to subarctic waters in North America and Eurasia. In North America, they range along the Atlantic coast from the Gulf of Mexico to Newfoundland, including the Great Lakes and the St. Lawrence, Missouri and Mississippi rivers with their basins, as well as along the West coast in major rivers from California to British Columbia. They occur along the European Atlantic coast, including the Mediterranean basin, in the rivers that flow into the Black, Azov and Caspian seas (Danube, Dnepr, Volga and Don), the north-flowing rivers of Russia that feed the Arctic Ocean (Ob, Yenisei, Lena, Kolyma), in the rivers of Central Asia (Amu Darya and Syr Darya) and Lake Baikal. In the Pacific Ocean, they are found in the Amur River along the Russian-Chinese border, on Sakhalin Island, and in the Yangtze and other rivers in northeast China.
Most sturgeons are anadromous bottom-feeders, spawning in fresh water and live at sea or near estuaries or undergoing significant migrations along coastlines. Some species, like Lake Sturgeon and the Baikal Sturgeon, have evolved purely freshwater existences. And some species, like White Sturgeon and Siberian Sturgeon, have been forced into them by anthropogenic or natural impoundment of their native rivers, the Columbia River for White and Ob River with it’s basin for Siberian Sturgeon. Some species are entirely freshwater species, very few venture into the open ocean beyond near coastal areas, like Shortnose sturgeons, which live primarily in areas where the water flow is slow, but they travel to faster-moving rivers to spawn.
Diagnostic characters of the Family:
Sturgeons are distinctive for their elongated body shape, lack of scales, distinctive scutes, occasional great size, flattened, slightly upturned snout, with the mouth located underneath, barbels, and elongated upper tail lobes. Sturgeons are polyploid; some species have 4, 8, or 16 sets of chromosomes.
Sturgeons have heavy, elongate and subcylindrical in section body. Their head is ending in a hard extended snout, long, thin, slightly flattened, and are equipped underside with 4 sensory barbels and a siphon-shaped, protrusible inferior toothless mouth. Some species have a spiracle (small opening above and behind eyes). Those 4 conspicuous barbells in front of the mouth are hang from the underside of the snout, feathered at the ends, are tactile organs that precede their mouth and are dragged along often murky river bottoms.
Their gill membranes joined to isthmus, not free, a single dorsal fin set far back on body and a caudal fin more or less deeply forked and distinctly asymmetrical, heterocercal, with a fleshy axis bending upward at base of fin and extending rearward to tip of upper lobe, the fin being much wider below than above fleshy axis. Their pectoral fins set low and the pelvic fins abdominal in position. All fins are spineless, except for first pectoral-fin ray which is ossified in some species. Sturgeons have an upward curved outline and a shark-like tail.
Sturgeons have cartilaginous skeleton for the most part and don’t have scales, their head and body are covered with bony plates, called scutes, shields, or bucklers. There are 5 rows of sharp spiky bony plates that run the length of the body, one along midline of the back, one along on each flank and two on the undersurface, and something on the rest of their skin that makes it slippery in one direction and sandpaper-rough in the other. The body color is variable, is light brown to dark brown, almost black or predominantly dark grey or greenish whilst the belly tends to be white.
Family Level Identifiers:
Body robust.
Five rows of longitudinal plates.
Dorsal and anal fin set posteriorly.
Four barbels underneath snout.
Sturgeons are among the largest fish found in the freshwater systems of North America.
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They have occasional great size, 7–12 feet (2-3.5 m) in length are common, and some species grow up to 26 ft (7.9 m). The world's largest known freshwater fish is Kaluga or Great Siberian Sturgeon has been recorded at 2200 lb (1000 kg), being as large as most great white sharks. The largest species of Sturgeons and the largest European fish entered fresh water is the huge Beluga Sturgeon (Huso huso), native to the Caspian Sea and Black Sea recorded length nearly 26 ft (7.9 m) and weight 4,565 lb (2,075 kg). A Shortnose Sturgeon measures about 4.7 feet (1.4 m) in length and about 51 pounds (23 kg) in weigh. The largest freshwater fish in North America, the White Sturgeon, can be 20 feet (6 m) long and weigh about 1,500 pounds (680 kg).
Habitats
Most sturgeon species inhabit large rivers, lakes, and coastal marine environments, generally but not always near the bottom. Some species are chiefly marine, spending much of their life in the ocean but migrating to fresh water to spawn. Marine dwelling sturgeons are mostly found in bays and estuaries. Preferred substrates include clean sand and gravel, where they feed primarily on bottom organisms such as worms, mollusks, crustaceans, snails, small mussels, and a variety of benthic organisms, and occasionally plant material. With their projecting wedge shaped snout they stir up the soft bottom, and use the barbels to detect shells, crustaceans and small fish, on which they feed. Having no teeth, they are unable to seize prey, though larger specimens can swallow very large prey items, including whole salmon.
Reproduction
Sturgeons are an anadromous fish, spending most of their life in near shore oceanic salt waters, bays, and estuaries and move to fresh water to spawn. Spawning takes place in the spring at the edge of the saltwater front that moves steadily upstream as runoff decreases. They prefer to spawn in lower reaches of large rivers with swift currents and large cobble substrates, but range from clean sand to bedrock substrates; no nest is built. These slow-growing and late-maturing fish are probably the longest-lived of the fishes; they can live for 118 years and attaining sexual maturity at 20 years or more. Sexually mature individuals range from 80cm to slightly over 2 m in length.
Importance
Humans are most familiar with the sturgeon because it is a famous source of caviar, unfertilized roe collected from female fish. The most expensive caviar, Almas caviar, is pearly white in appearance and comes from a 100+ year old Beluga Sturgeon. The lighter the color of Beluga caviar the older the fish is, the more expensive the caviar is. 1 kg of Almas caviar in a 24-karat gold tin cost £16,000, or about $25,000. The sturgeons were around in the early Jurassic period and still it is one of the main sources of caviar which processed from its ovary before the fish can spawn.
Sturgeon flesh is great quality, and the roe (eggs) of sturgeon is the well-known delicacy caviar. Sturgeons of all species, are delicious, and, despite being freshwater fish, not terribly bony. Their flesh is white, firm, meltingly smooth, delicately sweet, and not "fishy" at all. They can be smoked to marvelous effect, grilled whole, pan-fried, braised, or made into soup.
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