Vertebrate Zoology: A Study Guide - T. A. Dauda 2014

Multicellular Animals
Fishes
Class Osteichthyes - Subclass Actinopterygii - Order Salmoniformes

Salmonids are medium to large-sized fish characterized by a small fleshy fold on their back known as the adipose fin. They are primarily distributed in temperate and northern latitudes. Most salmonids are anadromous, growing and maturing in the ocean before returning to freshwater rivers to spawn. The seas of the Far East are particularly rich in salmonids, harboring species such as chum salmon, pink salmon, sockeye salmon, and others. These fish spawn in the upper reaches of rivers, with sockeye salmon also inhabiting lakes. Spawning Migrations can sometimes span several thousand kilometers. For instance, chum salmon travel up the Amur River for distances of up to 2,000 km from the Mouth, depositing their eggs in shallow depressions they excavate in the riverbed, which they then cover with fine gravel or sand. The juveniles overwinter in rivers and migrate downstream to the sea in the spring. Adult fish die after spawning, meaning they reproduce only once in a lifetime. Their fecundity is relatively low: 3,000 to 4,000 eggs in chum salmon, and 1,000 to 2,000 in pink salmon.

The salmonid family includes the Atlantic salmon (sämga), native to the Barents and White Seas, and the sea trout (kumža), found in northern seas as well as the Black and Caspian Seas. A dwarf form of the sea trout—the trout—finds optimal living conditions in northern and mountain rivers, as well as certain cold, clear mountain lakes.

Some Representatives of the salmonid family, such as whitefish, omul, and taimen, reside permanently in freshwater bodies.

Salmonids are of major commercial importance. Their meat and roe (caviar) are highly prized. The bulk of salmonids in our country are harvested in the rivers of Siberia and the Far East, targeting species such as chum salmon, pink salmon, and whitefish. Other commercially valuable species include the Baikal omul, Peipus whitefish, vendace, and Caspian inconnu.

Heavy harvesting of salmonids, combined with their low reproductive rate, has necessitated extensive restocking efforts through state-run hatcheries, which have proven highly effective. For example, the survival rate of juvenile chum salmon reaching the sea exceeds 90% of the incubated eggs, whereas under natural spawning conditions, only about 10% of the fry make it to the sea.