In the basin of river Amur there are 3 species of sturgeon: kaluga (Huso dauricus), Amur (Acipenser schrencki) and Sakhalin sturgeon (Acipenser mikadoi).
Kaluga and Amur sturgeon are endemic to the Amur. Therefore, they can rightfully be considered symbols of the Amur. These are giant fish of ancient origin with a very peculiar way of life and appearance: sharp ridges along the spine, a narrow long snout with large fleshy lips and a cartilaginous skeleton. Cartilaginous fishes are first fish, which means that kaluga and sturgeon are real relicts, living and successfully reproduce in the Amur for millions of years. They live and spawn in the main channel of the Amur, less often entering largest tributaries. They make long migrations: the Amur sturgeon descends to the Amur estuary, and kaluga for foraging makes way to the Sea of Okhotsk and the Sea of Japan, reaching Kamchatka, Kuril, Hokkaido and even Primorsky Krai! Such a vast marine range is not found in any other freshwater fish of this size. Over a length of several thousand kilometers, migrations of Kaluga are comparable only to migrations of migrating salmon, but in contrast to Pacific salmon, sturgeon are
Sakhalin sturgeon is one of the most unusual sturgeon fauna of Russia. It lives in the sea (the Sea of Okhotsk, the Tatar Strait, the Sea of Japan), and spawns in relatively large rivers with particular estuary zones, characterized by extended stretches from the mouth upstream, where during high tide the seawater reaches along the bottom. In such places there is an extensive feeding base for young sturgeon, which lives there for up to four years before leaving the river and going to sea. The advance of juveniles from fresh water to sea water is gradual. The larva of Sakhalin sturgeon, released from eggs, instinctively hides under the stones, so that it will not be carried off by rapid current into saltwater section of the river. This behavior is fundamentally different from the behavior of larvae of other sturgeons of our fauna, spawning in rivers with a more calm current and actively swimming in search of food.