Beluga Sturgeon ( Huso Huso )
Photograph provided by New Orchard Fisheries
Facts
Also known as:- Great sturgeon
Kingdom:- Animalia
Phylum:- Chordata
Class:- Actinopterygii
Order:- Acipenseriformes
Family:- Acipenseridae
Genus:- Huso
Size Length:- 1 - 3 (max = 5 m)
Weight Up to:- 2,072 kg
The Beluga is the most well known of the caviare sturgeons.
Status
The International Union for Conservation of Nature (IUCN) has classified the Beluga as Endangered.
It is a protected species listed in appendix III of the Bern Convention and its trade is restricted under CITES appendix II. The Mediterranean population is strongly protected under appendix II of the Bern Convention, prohibiting any intentional killing of these fish.
The United States banned import of beluga caviar in 2006 after listing beluga sturgeon under the U.S. Endangered Species Act.
Description
The beluga or European sturgeon (Huso huso) is an anadromous fish in the sturgeon family (Acipenseridae) of order Acipenseriformes. Anadromous fishes are those that spend all or part of their adult life in salt water and return to freshwater streams and rivers to spawn. The beluga is found primarily in the Caspian and Black Sea basins, and occasionally in the Adriatic Sea. Due to this, sturgeons are sometimes likened to sea fish; however most scientists consider them to be river fish.
It is heavily fished, and often poached, for the female's valuable roe, which is as known as beluga caviar. Because of this, the species numbers have been vastly reduced and some governments have put restrictions on fishing and trade, (see above). The beluga is a huge fish, however it is slow-growing and late to mature, one of the reasons why beluga caviar is so expensive.
It can live up to 118 years and some documented specimens have been measured at nearly 6 metres (19 ft), however some unverified sightings have claimed them to be larger. The beluga is an ancient fish, and has survived from the time of the dinosaurs and it's appearance and characteristics seem to underline this. It has an elongated body shape with a flattened snout that turns up slightly at the end. The mouth is located underneath and slightly back from this, as with other sturgeon species, probably giving rise to the idea that they clean the bottom of rivers and ponds. This is untrue as they cannot digest plant material. The short, fleshy barbels that are situated in front of the mouth are feathered and very sensitive. They are used to locate food, another thing that has given rise to the myth that they are bottom cleaner fish. In fact, the beluga is a predator that feeds on other fish as it requires a diet that is high in animal protein. They have five rows of bony plates that run the length of their body, one on the back, one on each side and two underneath. These are known as skutes. The body is mainl dark grey or greenish grey in colour whereas the underside is a lot paler, almost white.
The English name comes from the Russian which derives from their word (belyy), meaning "white".
Biology
The beluga can take up to 18 years to reach sexual maturity and even then they only spawn once in every 2 to 4 years. The adults migrate upstream in the spring or autumn to spawn in shallow freshwater pools. A single female can produce between 300,000 and 7.5 million eggs, which fall to the pool floor and attach to the stones there. Once hatched, the juveniles migrate downstream, returning to the sea.
The fleshy barbels in front of the mouth (as described above) are used to search for prey on the riverbed and also the seafloor. Young beluga feed mainly on small invertebrates whereas the adults tend to consume fish such as anchovy, gobies and herring. Belugas spend the majority of their time in the lower reaches of the water column, near to the substrate (the surface on or in which plants, algae, or certain animals, such as barnacles or clams, live or grow. A substrate may serve as a source of food for an organism or simply provide support).
Threats
As previously mnetioned some populations of the beluga are threatened with commercial extinction, primarily as a result of overfishing. The eggs, or roe, are highly prized as caviar, this is due to their quality and quantity. The beluga is entered in the Guiness Book of Records as 'the most expensive fish'. In 1998 it was estimated that over 55% of the caviare trade was illegal, due to the collapse of effective management in the Caspian Sea. Added to this the destruction of habitat and loss of spawning grounds, coupled with the increase in pollution, the beluga's numbers in the wild are declining. The Volgograd Dam for example, has blocked almost all beluga spawning grounds as the Volga river is the principal spawning ground.
Conservation
Most of the sturgeon population is now supported artificially. Fish farms and hatcheries may be the principle reason that belugas still survive in the Caspian Sea. As the United States are the biggest importer of caviar the Fish and Wildlife Service is currently considering listing the species under the Endangered Species Act, effectively banning importation, but time is running out in the fight to save this ancient fish.
