Sturgeon

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 long-lived fish and can spawn multiple times, each time giving multiple offspring. One kaluga individual can lay 4 million eggs!

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.

The Zeya-Burein populations of kaluga and sturgeon are listed in the Red Book of Russia in the first category as «endangered populations of endemic species». All of Amur sturgeon are listed in the IUCN Red List and the CITES Convention. In 2013, kaluga, Amur and Sakhalin sturgeon were included in the list of valuable species, illegal extraction of which is a criminal offense. The Amur is practically the only river of Eurasia, where populations of these sturgeons are not fragmented by large dams. Figuratively speaking, the Amur is a «river of Caviar», but because of irrational use, it is rapidly losing its significance. At the end of the nineteenth century, up to 11,000–12,000 centners of sturgeon were caught in the Amur, half of which were kaluga. Despite the prohibition of commercial sturgeon fishing, numbers of these fish are getting smaller every year. Kaluga and Amur sturgeon suffer, above all, from illegal fishing. This extraction brings such a significant income that poachers are better equipped than organizations that are designed to combat poaching. It will soon be forgotten that kaluga can weigh more than a ton, since now, for the most part, the first spawning individuals weighing more than 100 kg are rarely caught. According to experts, individuals of Sakhalin sturgeon located on the territory of the Russian Federation are even rarer (less than 300 ind.) than Amur tigers that are on the verge of extinction (more than 450 ind.).