Sturgeons: 7 Awesome Facts about these Living Fossils

2. Sturgeon fish have either 120, 240, or 360 chromosomes

Sturgeon underwent genome duplication during evolution. Genome duplication is the process of genes being copied. So the sturgeon species that are not extinct can be divided into three groups based on how many chromosomes they have. Species either have 120, 240, or 360 chromosomes. The white sturgeon has 240 chromosomes. Species with these chromosomal variations are considered polyploidy. This occurs much more commonly in plants.

3. Sturgeons have bony plates called scutes instead of scales

Unlike most fish, sturgeons do not have scales. Instead they have scutes. Scutes are bony plates that are like a built in armour. Each sturgeon has five lateral rows of scutes along its body. Scutes are very sharp. They protect the sturgeon from abrasions and possible predators. Although mature sturgeons are so large they do not have any natural predators, younger green sturgeon, which are only a few feet long, have extra sharp scutes.

The shovelnose sturgeon has plates along its belly

Shovelnose sturgeon are a small species that live in the Mississippi River. Shovelnose sturgeons are much smaller than their cousin and neighbor, the pallid sturgeon. In fact, a shovelnose can only grow up to 1m. Their small size makes them vulnerable to predators. So unlike pallid sturgeons, shovelnose sturgeons have plates along their bellies. These plates provide extra defense.

4. Sturgeons have syphon-like mouths and no teeth

Even though sturgeons are among the biggest fish in the world, they are bottom feeders, rather than predators. In fact, sturgeons have no teeth to chew on prey. Instead, sturgeons extend and open their mouths to suck up food from the benthos of its environment. The benthos is the lowest level of a body of water’s floor. Sturgeons usually suck up small fish, shellfish, and crustaceans. However, a large white sturgeon can swallow a salmon fish whole.

Sturgeon fish have four whisker-like barbels

Near their mouths, sturgeons have four long, thin barbels.  Barbels on sturgeon are like whiskers on a cat. The barbels provide sensory input about the sturgeon’s environment. A sturgeon will swim near the water’s floor, dragging its barbels through the sand to feed. The barbels will tell the fish where the food is. Sturgeons have poor eyesight. But barbels sense food so that the sturgeon don’t have to see it.

5. Most sturgeon grow between 2-3.5m (7-12ft)

Sturgeons are among the biggest fish in the ocean. On average, sturgeons grow up to 7-12 feet long. However, some species grow much larger, while others are smaller. Mature white sturgeons are usually only 6.9 feet long. While mature lake sturgeon can reach 9 feet. However, scientists have noticed that many sturgeon fish are not growing as large as they once did.

Female atlantic sturgeons are larger than the males

Within most species of animals, males are on average larger than females. For example, the average human male is 5’10” while the average female is only 5’4”. However the opposite is true for the Atlantic sturgeon. A mature male Atlantic sturgeon can reach 6’-7’ and weigh 65 pounds. While a mature female can reach 10’ and weigh 250 pounds.

The Beluga Sturgeon can grow over 20ft long and weigh 3500 pounds

The biggest sturgeon species is the beluga sturgeon. A mature beluga sturgeon can reach 24ft long, and weigh 3500 pounds. Like the Atlantic sturgeon, female beluga sturgeons are larger than the men, usually 20% larger. And the beluga sturgeon isn’t just the largest sturgeon. They are also among the biggest fish in the ocean.

6. Sturgeon live between 55-150 years

Sturgeon are long-living fish. They usually live between 50-60 years. However, many species can live between 55-150 years. Most species do not have any natural predators, so they can survive in the wild for over a century so long as they have food and access to migration pathways.

Sturgeon reach maturity very slowly

Sturgeons are long-living fish. However, it takes over a decade for sturgeons to reach maturity. On average, a sturgeon fish doesn’t spawn until it is between 15 and 20 years old. The long-lasting juvenile period of a sturgeon’s life is also the most dangerous. For example, the lake sturgeon is considered valuable as food, but most fish caught before the age of twenty have not spawned.

7. Sturgeons, like salmon, reproduce in freshwater

Marine sturgeons are anadromous fish. This means that they live in saltwater, but migrate to freshwater to reproduce. Mature sturgeons migrate from oceans to rivers.  Female sturgeons lay between 100,000-3 million eggs in clear water with shallow rocks. Male sturgeons will then fertilize the eggs. Several males can fertilize the eggs of a single female. The fertilized eggs are sticky, and adhere to the rocks. Females prefer to lay eggs in fast-moving waters so that the eggs will spread out.

Unlike most sturgeons, the beluga sturgeon reproduces every year

Most sturgeon species do not reproduce every year.  Once sturgeons reach sexual maturity, environmental conditions have to be just right for them to lay eggs.  For example, the water temperature and flow have to be just right.  Beluga sturgeons are an exception.  Once a beluga sturgeon reaches maturity, it will migrate upriver every year to spawn.  Beluga sturgeon migration begins in the autumn.  They spend winter resting in freshwater before spawning.

So Can a Sturgeon Kill a Human?

Sturgeons are not aggressive towards humans. Scuba divers who have met sturgeons say that the animals are very shy, and avoid humans. As if we are the 20 feet sea monsters. Sadly, humans are much more predatory to sturgeons than the other way around. Sturgeon eggs are very small and bead-like. Humans consider them a delicacy. So they sell them for consumption as “caviar.” And yes, caviar tastes as gross as it sounds.

• Sturgeons are critically endangered
  ‍Sturgeons are not a fast reproducing species.  This has made it easy for human activity to decimate the populations of several sturgeon species.  For example, the Chinese sturgeon population decreased 98% between 1973 and 2010.  A combination of overfishing and human construction has been largely to blame for the near extinction of sturgeons.
• Construction and logging block sturgeons’ access to breeding waters
  ‍The lake sturgeon lives in the Great Lakes of the American midwest.  These sturgeon leave the lakes to spawn, and then come back.  However, human industry happening near the lakes has hurt the lake sturgeon population.  Logging and newly built dams block sturgeons’ access to rivers for breeding.  These same obstacles can also trap lake sturgeons in rivers on their journeys back to the lakes.
• Beluga sturgeon eggs are worth $3500 per pound
  ‍Beluga sturgeon eggs are used to make “caviar.”  Caviar is considered a luxury food in many parts of the world.  Fishermen can sell one pound of beluga sturgeon eggs for $3500 (that’s $8000 for one kilo).  Overfishing for the delicacy in Russia and the Middle East has caused populations to decline rapidly.  As the population declines, the eggs become rarer and thus, more valuable.