The Siberian sturgeon (Acipenser baerii) is a large species of fish that can measure up to 2 metres long. The heaviest individual recorded was an astonishing 210 kilograms! These enormous fish can be found migrating across most river systems in Northern Russia. There are also non-migratory populations in Lake Baikal, the largest freshwater lake in the world, located in Southern Russia. A single Siberian sturgeon can live for over 60 years; feeding primarily on small organisms that live on the bottom of the river such as small worms, insect larvae and crustaceans.
Farming Process
The rearing of Siberian sturgeon to turn a profit became common in the 1970’s, in what is now Russia. Global annual catches often exceeded several hundred tonnes, with much more being harvested in the present day. In 2017, a survey recorded 2,329 commercial sturgeon farms in 46 countries. The growth of sturgeon farming has been so steep that the global harvest in 2017 was four times larger than all the global harvests from 1970-1980 added together.
Distinguishing between males and females is extremely difficult, so ultrasound scans take place when the fish are approximately 3 years old to determine their gender. Males are then sold on to be harvested for their meat. Females however are kept and reared until mature enough to produce caviar. Caviar is sturgeon eggs, frequently considered a delicacy in many countries around the world.
Females can start producing eggs as young as 7 years old, but usually begin producing significant numbers of eggs at around 12-15 years old. After many years of egg production, females with the highest yield are kept for producing new generations. Those with lower yields are harvested for their meat.
Caviar
To this day, Siberian sturgeon remain one of the most profitable species in Russia. Their meat is sold fresh, pickled, or smoked. The inner membrane of the swim bladder is used to make a product called “isinglass” which is a very pure form of gelatin. However, the real money lies within the caviar industry.
Caviar harvested from Siberian sturgeon is often sold for over £1,000 per kilogram. Each female is capable of spawning every other year – sometimes every year – and producing up to 9 kilograms of eggs per spawn. With a reproductive life span of over 50 years, the financial appeal of caviar farming is clear.
Conservation
Siberian sturgeon are one of 27 sturgeon species and are classed as endangered by the IUCN (International Union for Conservation of Nature). Unfortunately 63% of all sturgeon species are listed as critically endangered, with 4 species thought to be possibly extinct already. Declines in sturgeon populations are largely due to:
- Over fishing for meat and caviar production
- Dam building blocking migration routes
- River pollution
- Habitat degradation and loss
A key reason for conserving all sturgeon species is they act as a living fossil record. The sturgeon family is one of the oldest fish families on record, with fossils dating back to the mid Jurassic period, some 174 million years ago.
Here at Blue Planet, we have two species of sturgeon: Siberian and Diamond back. Found in our Northern Streams area, we consistently educate visitors on the importance and history of these fascinating fish. Although global caviar sales have been slowly reducing over the last 5 years, it’s possible many sturgeon populations may not bounce back from the decades of exploitation imposed upon them by the caviar industry. Hopefully – after existing on Earth for over 170 million years – harvesting limits and habitat management can ensure all sturgeon species continue to exist long into the future.