Sturgeon, << STUR juhn, >> is a large fish whose long, slender body is covered in tough skin and bony plates, instead of scales like most other fish. Sturgeons live in both fresh and salt water in the North Temperate Zone, the region between the Tropic of Cancer and the Arctic Circle. Fishing crews catch sturgeon for their flesh, which processors usually smoke (preserve and flavor by exposure to smoke and heat). Manufacturers salt the eggs of sturgeon to make the delicacy called caviar.
Rows of bony plates protect the body of the sturgeon, and additional plates protect the head. Beneath an adult sturgeon’s long snout lies a small, toothless mouth with thick, sucking lips. The fish uses these lips to suck up crustaceans, fish, worms, and other animals that live on the water’s bottom. Four long, thin, fleshy growths called barbels project from in front of the mouth. A single dorsal fin rises from the sturgeon’s back. A sturgeon’s body extends into the long upper part of its tail fin.
Most sturgeon live in salt water, migrating into streams during the spawning (egg-releasing) season. However, some species of sturgeons live only in fresh waters.
Sturgeon belong to an ancient group of fish whose bodies have changed relatively little since the time of the dinosaurs. Early ancestors of the sturgeon appeared more than 150 million years ago, during the Jurassic Period. The sucking mouth and plated body of the sturgeon developed later.
The sturgeon family includes about two dozen species. The common sturgeon, one of the best-known species, lives in European waters. A related species, the Atlantic sturgeon, lives along the North American coast from Labrador to the Gulf of Mexico. The white sturgeon of the American Pacific Coast ranks as the largest American freshwater fish. It grows to 20 feet (6 meters) long and may weigh more than 1,500 pounds (680 kilograms). The lake sturgeon lives in the Great Lakes and the waters of the Mississippi Valley.
Scientists consider the beluga or Russian sturgeon to be the largest freshwater fish. It lives in the Black and Caspian seas. The longest known beluga measured 28 feet (8.5 meters). The heaviest known beluga weighed 4,568 pounds (2,072 kilograms). Beluga eggs produce the most valuable caviar. Along with giant white sturgeons, belugas can live more than 100 years.
Sturgeon were once abundant throughout the world. However, overfishing, pollution, and the construction of dams have greatly reduced their numbers. The Yangtze sturgeon, which was once found in East Asia, is extinct in the wild. All other species of sturgeons are threatened with extinction.
See also Caviar.
