Sardine is an important food fish. The word sardine refers to several groups of fishes. But it is used mainly for such species as the Pacific sardine and the European sardine, also called the pilchard. Members of the herring family, including sprats and young Atlantic herring, are also sold as sardines. The fish were called sardines because they were first caught near Sardinia, an Italian island in the Mediterranean Sea.
Sardines live in temperate to tropical ocean waters near the shores of almost all the continents. They are especially plentiful off the coasts of Japan, northwestern Africa, and western South America. Sardines average 9 to 12 inches (23 to 30 centimeters) in length and about 4 ounces (113 grams) in weight. The upper part of their body is bluish-gray, and the lower part is silvery. Adult sardines usually swim in large schools. They feed on small aquatic organisms called plankton.
Most sardine fishing takes place on moonless nights. The movement of sardines disturbs tiny organisms that live near the surface of the sea. The movement causes these organisms to produce light by means of a chemical reaction. This light, called bioluminescence, reveals the presence of sardine schools. Most sardines are caught with a special type of net called a purse seine.
The U.S. fishing industry caught great numbers of Pacific sardines until the mid-1940’s. At that time, the catch of these sardines began to decline severely. The decline probably resulted from a combination of excessive fishing and unfavorable environmental conditions. In 1967, the California legislature stopped all sardine fishing off the coast of California. As a result, the Pacific sardine population in U. S. waters began to increase. In 1986, California started to allow limited sardine fishing. 
Cans of sardines are a familiar sight on supermarket shelves. Canneries precook sardines and remove part of their natural oil and moisture. Industry uses sardine oil in such products as linoleum, paint, and varnish. Some sardines are made into fish meal, which is used in animal feed and fertilizer. Small sardines are used as bait in commercial tuna fishing.
See also Fishing industry; Overfishing.
