A sturgeon is a large, primarily freshwater fish belonging to the family Acipenseridae, with about 27 species known to exist.
They can be found in temperate waters of the Northern Hemisphere, and most species live in the ocean, ascending rivers to spawn in spring or summer.
A few species, however, are confined to fresh water.
Sturgeons date back to the Late Cretaceous period, with fossils providing evidence of their existence some 174 to 201 million years ago.
They are closely related to paddlefish and are known for their long lifespan and impressive size. Atlantic sturgeons, for example, can grow up to 16 feet long and weigh as much as 800 pounds.
These fish are characterized by their bluish-black or olive brown color, paler sides, white belly, and bony plates, known as “scutes,” which run along the length of their body.
Usually found in the Atlantic and Pacific Oceans, sturgeon meat is considered a delicacy, often compared to shrimp or crab in terms of taste and texture. As a result, it is sought after in the culinary world and can be rather expensive.
In addition to their significance as a food source, sturgeon also play an important role in various ecosystems, making them an essential focus for fisheries management and conservation efforts.
Table of Contents
What Is a Sturgeon?
Sturgeon refers to the common name for the 27 species of fish belonging to the family Acipenseridae.
These large, primarily freshwater fish are native to temperate waters of the Northern Hemisphere.
Most species of sturgeon live in the ocean and ascend rivers, sometimes once every few years, to spawn in the spring or summer. However, a few species are confined to fresh water.
The ancestry of sturgeon dates back to the Cretaceous period, more than 120 million years ago.
The most primitive of all bony fish, their lineage is believed to have lived alongside dinosaurs. Their closest relatives are the paddlefish, making them akin to living fossils.
Sturgeons are characterized by their elongated bodies, covered in bony plates called scutes, rather than scales.
They possess a heterocercal tail, which means the upper lobe is larger than the lower lobe. Sturgeons also have a vacuum-like mouth, designed for bottom-feeding, and they typically consume invertebrates such as crustaceans, worms, mollusks, and bottom-dwelling fish such as sand lance.
These impressive fish are known for their large size and long lifespan, with some species growing up to several meters in length and living for several decades.
Due to their unique biology and behavior, sturgeons have become a subject of interest to research and conservation efforts.
Physical Characteristics
External Anatomy
Sturgeons are large fish that can grow up to 22 feet in length and weigh between 200 and 1,800 pounds.
They have a unique appearance, with a greenish-grey coloring and an elongated, spade-like snout.
On their snout, sturgeons have two pairs of whisker-like organs called barbels, which dangle near their mouths and aid in locating food.
Their skin is smooth and instead of scales, they possess bony plates known as scutes, which provide protection.
These fish have a heterocercal tail, resembling a shark’s, where one lobe is larger than the other.
Their fins are positioned along the length of their body, with a large dorsal fin set further back towards their tail.
This anatomy not only gives the sturgeon its unique appearance but also aids in swimming and maneuvering through different water environments.
Internal Anatomy
Sturgeons have a cartilaginous skeleton rather than a bony one, which contributes to their flexibility and adaptability in various aquatic habitats.
Their swim bladder plays a significant role in maintaining buoyancy, allowing the fish to either swim close to the water surface or stay near the bottom when searching for food.
They possess a spiral valve in their intestine, a primitive feature found in some fish species that increases the surface area for nutrient absorption.
In terms of reproductive anatomy, males and females both have paired gonads.
During spawning, eggs and sperm are released into the water simultaneously for external fertilization.
Habitat and Distribution
Sturgeons are a family of fish (Acipenseridae) that are native to temperate waters of the Northern Hemisphere.
They display a variety of habitat preferences, which can be divided into anadromous and freshwater species.
Anadromous sturgeons typically inhabit river deltas and estuaries, and migrate upstream to spawn in freshwater environments.
Some species inhabit freshwater environments exclusively, while others mainly reside in marine environments near coastal areas, and are known to venture into the open ocean.
Most sturgeon species are bottom-feeders and forage near the bottom of rivers, lakes, and other aquatic ecosystems.
They can be found in freshwater habitats such as rivers, lakes, and ponds, as well as saltwater or brackish water environments.
When it comes to reproduction, sturgeons typically migrate to freshwater habitats to spawn following seasonal patterns.
A few examples of sturgeon distribution include:
- Atlantic sturgeon, which live in rivers and coastal waters from Canada to Florida. These fish hatch in freshwater and head out to sea as sub-adults before returning to their birthplaces to spawn.
- Shortnose sturgeon, found in 41 bays and rivers along the East Coast of the United States. Their distribution is fragmented, with a large gap in their range along the coast.
Conservation efforts for sturgeons include preserving and restoring habitats, monitoring bycatch, and promoting population recovery through regulations and management plans developed in collaboration with various partners, such as NOAA Fisheries.
Lifecycle and Reproduction
Sturgeons are fish species belonging to the family Acipenseridae, predominantly found in the Northern Hemisphere’s temperate waters.
The sturgeon’s lifecycle begins with the spawning process, which occurs in rivers and freshwater environments.
Sturgeons have several types, such as Atlantic sturgeon, White sturgeon, and Green sturgeon.
During the spawning season, usually in spring or summer, the female sturgeon lays eggs, and a male sturgeon fertilizes them.
The spawning interval varies among sturgeons: males spawn every 1 to 5 years, whereas females spawn less frequently, between 2 to 5 years.
An essential prerequisite for successful spawning is finding appropriately deep rivers with the correct flow and a water temperature between 14°C and 18°C.
Once fertilized, the eggs hatch and initiate the young sturgeon’s growth stage. A sturgeon’s growth rate depends on factors such as food availability and environmental conditions.
To mature, sturgeons need several years, with some species like Green sturgeon reaching maturity around age 15.
Sturgeons are known for their longevity, living up to 60 to 70 years in some species.
As they grow, the number of eggs produced by females also increases, ranging from 400,000 to as many as 2 million or more, depending on the species and size of the female sturgeon.
Spawning sites are usually characterized by faster currents and rockier bottoms compared to feeding areas.
Unlike salmon, sturgeons can spawn multiple times throughout their lives, returning to their native rivers every few years to reproduce.
This characteristic allows sturgeons to have a recurring impact on their respective habitats, contributing to the ecosystem’s health and stability.
Diet and Feeding
Sturgeons are opportunistic feeders, meaning they consume a variety of food items they come across in their natural habitats.
Their diet primarily consists of insect larvae, macroinvertebrates (such as crabs, shrimp, mussels, and barnacles), small benthic fish, snails, and other bottom dwellers.
These fish feature a unique feeding mechanism, as they have no teeth for biting or tearing their prey.
Instead, sturgeons create suction using their mouths, which are positioned underneath their heads.
This adaptation allows them to efficiently forage along the bottom of water bodies, vacuuming up food found on lake and river beds.
In captivity, sturgeons are typically fed a more restricted diet as compared to their wild counterparts.
Pellets and flakes specifically designed for these fish are the primary food sources provided in such settings.
Below is a breakdown of common food items found in the natural diet of sturgeon species:
- Crustaceans
- Shellfish
- Small fish
- Aquatic insects
- Insect larvae
- Snails
- Plants
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