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(sturgeons), a family of cartilaginous ganoid fishes. The snout is more or less elongated, and the jaw is toothless and protractile. There are four barbels in front of the inferior mouth. The internal skeleton is cartilaginous. The body is covered with five rows of bony scutes and with bony granules and plates. The anterior rays of the pectoral fins resemble thick spines. The largest representatives of the family (Huso) reach a length of 9 m.
There are four genera of sturgeons, embracing 23 species. The genera are Huso, Acipenser, Scaphirhynchus, and Pseudoscaphirhynchus. The genus Huso has two species, the beluga (Huso huso) and the kaluga (H. dauricus). The Acipenseridae are distributed in the northern hemisphere; they are found as far south as the tropic of Cancer. All species reproduce in rivers, that is, only in fresh water. They spawn in the spring and summer, usually in rapids with gravelly bottoms; the roe adhere to the bottom.
Some Acipenseridae, such as the Scaphirhyncus, Pseudosca-phirhyncus, the sterlet (Acipenser ruthensis), and the lake sturgeon (Acipenserfulvescens), are freshwater fishes. The remaining species are semimigratory or migratory; they enter rivers for laying roe and return to the sea for feeding and growing. The young of migratory species roll down to the sea. In some migratory species there are freshwater and semimigratory forms. Sexual maturity is usually attained by the eighth to tenth year or later. Some species of Acipenseridae are predators; these include the beluga and the kaluga. Some species, such as the sturgeon (Acipenser sturio) and the sterlet, feed principally on benthic invertebrates.
The Acipenseridae are very valuable commercial fishes. The USSR accounts for the largest proportion of the world catch. The number of some migratory species has sharply declined owing to the disturbance of conditions of reproduction and, in some bodies of water, excessive fishing.
REFERENCESZhizn’ zhivotnykh, vol. 4, part 1. Moscow, 1971.
Nikol’skii, G. V. Chastnaia ikhtiologiia, 3rd ed. Moscow, 1971.
V. M. MAKUSHOK