[1] With a maximum size of at least 1,000 kg (2,205 lb) and 5.6 m (18 ft), the kaluga is one of the biggest of the sturgeon family.

However, kalugas are known to have an aggressive nature, and instances of them toppling fishing boats and drowning fishermen have been reported, although no concrete evidence exists of them assaulting or hunting people.

The mouth takes up the entire lower surface of the snout, it is lateral, crescent-shaped, and extremely large.

However, environmental factors such as warm water temperatures pose risk for fungus over free embryos and could be a cause of death also.

Kaluga Sturgeon hatch in shallow gravel beds in the freshwater estuaries of the Amur River.

Adult Kaluga Sturgeons travel in small groups of between 3 and 20 individuals to the shallow gravel beds to spawn.

They eat pike, carp, herring, chum salmon, keta, and most other fish or shellfish that can fit into their mouths.

After World War II, in 1948, 61 metric tons of Kaluga was caught, an unbelievable number for a species of their size.

[6] They are extremely vulnerable to extinction by poaching because they have late sexual maturity, which only occurs after around 6 to 25 years of age.

The animals are being hunted down for their unfertilized eggs because sturgeon roe is considered a delicacy to people all across the world.

[1] Data regarding the population trends of the Kaluga sturgeon is primarily based on various catch methods and efforts.

While no commercial fisheries currently target this species, it faces severe threats from illegal fishing, particularly in Russia.

This combination of factors has led to an estimated decline of over 90% in just 90 years, equivalent to roughly three generations of the species.

[9] The Kaluga is protected by Appendix II of CITES,[2] which includes species that although currently not threatened with extinction, may become so without trade controls.

Commercial sturgeon fishing was prohibited in the Soviet Union during the periods 1923–1930, 1958–1976 and from 1984 to the present (Vaisman and Fomenko 2007).

The Kaluga sturgeon was listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in 1998.