Beluga Sturgeon

The beluga sturgeon is found not only in the Caspian and Black Seas (and at one time in the Adriatic Sea) but also in ancient Greek, Roman, and Chinese literature, which describes the harvesting of this fish. Its name is derived from its characteristic white underbelly. Beluga comes from the Russian word belyj, which means “white.”

This fish is prized for its roe for caviar, and poachers and overfishing have brought this species nearly to its proverbial knees. With its population so greatly reduced, the International Union for Conservation of Nature (IUCN) has listed it as critically endangered. In 2005, the United States made it illegal to import beluga caviar in an effort to discourage the poaching and overfishing of this species of sturgeon.

As the third largest living species of bony fish in the world and the largest sturgeon, the beluga or great sturgeon (scientific name Huso huso) belongs to the order Acipenseriformes and one of the oldest families of fish, Acipenseridae, with some of their ancestors dating back to the Early Jurassic Period, nearly 200 million years ago. This family includes 27 different species commonly referred to as sturgeons.

As a protected species, it is illegal to catch and kill beluga sturgeon. Nevertheless, it is done, primarily because their roe is considered a delicacy. Beluga caviar is one of the most coveted and expensive in the world. The most expensive caviar, called Almas, comes from the albino beluga sturgeon. The eggs are whitish in color compared to the traditional and more common light grey or black. Almas caviar can cost more than $15,000 per pound.

Appearance 

The largest living freshwater fish in the world, beluga sturgeons can weigh more than 3,000 pounds and grow up to 20 feet in length. In 1827, the largest beluga on record — weighing 3,463 pounds and measuring 23 feet, 7 inches long — was taken in the Volga estuary in modern-day Russia. 

The beluga features an elongated body, shark-like tail, no scales, a series of bony plates called “scutes,” and a skeleton that is partially made of cartilage. The scutes and their very thick skin act as a defense against biting fish, although this sturgeon is more predator than prey. 

The fish’s elongated body is dark grey, except for its white underbelly, which gave the beluga sturgeon its name. The sturgeon’s body can even appear olive-green in color. Their snout has barbels or “whiskers” similar to what catfish have; this helps them locate prey in the water.

Over time, their appearance changes somewhat. Young belugas are long and slender, with a thin and pointed snout. Their heads are narrow, and their mouths project upward. As they age, belugas grow noticeably heavier in the head and the front half of the body, and develop a humpbacked shape. The snout becomes quite short, and their large mouth appears to “frown” underneath the snout.

Distribution, Population, and Habitat

The beluga sturgeon calls home the Caspian and Black seas, two large inland freshwater lakes, despite their being called “seas.” Although technically freshwater, they do have a low level of salinity. The Caspian Sea, for example, has about one-third the average salinity of seawater. In these environments, the beluga will live around the mid-range of the depth of their habitat, constantly monitoring these areas for food. 

As one of the largest predatory fish on Earth, the beluga sturgeon is the only species of sturgeon that actively eats other fish. Small, young sturgeons will feed on invertebrates in shallow waters, areas where they grow very quickly. Their diets become primarily other fish once they reach 3-4 inches in length. 

Beluga sturgeons have no natural predators, largely due to their size. However, they do have one of note: humans. These ancient giants are heavily fished for their highly valued roe, so it is accepted that their populations have decreased over the past 25 years, although the exact population of the beluga sturgeon is unknown.

In addition to being critically endangered, per the IUCN, beluga sturgeon are protected under the U.S. Endangered Species Act and are subject to international trade regulations.

Efforts to protect them extend to international trade agreements, too: CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) is a multilateral treaty geared at ensuring that the international trade of animals and plants does not threaten their survival.

Reproduction and Lifespan

Beluga sturgeon spawn in two stages. First, they migrate into a river in the autumn and overwinter there. When it is ready to spawn in the spring, the beluga begins to move inland through the estuaries and rivers. Some will travel more than 1,000 miles up the Danube, Volga, or other nearby rivers to spawn.

Like many species of fish, the beluga reproduces externally. This is accomplished when the male and female release, respectively, their sperm (usually more than a million of them) and eggs separately into the water. If the conditions aren’t suitable for spawning, then the female can choose to reabsorb the eggs and try again later. Females reproduce every four to eight years, on average.

The juveniles emerge from the eggs after a short time with a rather thin and small body. By the time they reach the sea (usually around May or June), they are still only a few inches long. In order to grow, the sturgeon has a very long development time and lifespan, most of which is spent alone.

Females reach sexual maturity at around 16–22 years of age, while males mature at 12–16 years.

The life expectancy of a beluga is usually at least 50 years in the wild, but it is almost always caught and killed by fishers before it can die of natural causes. If it does somehow manage to evade human capture, the sturgeon’s lifespan is truly prolific. One specimen was once observed to live for more than a century.