Sturgeon
Sturgeons are remarkable freshwater fish known for their impressive size, longevity, and unique physical characteristics. They can grow between 3 and 20 feet long and weigh from 300 to over 1,000 pounds, making them the largest freshwater fish species. With lifespans that can exceed 100 years, sturgeons are also recognized as the longest-lived fish. Their bodies are covered in heavy, bony plates called scutes, which provide protection, and they possess sensitive barbels that help them locate food on the river or lake bottom, primarily consisting of invertebrates.
Sturgeons are anadromous, meaning that while some species spend their entire lives in freshwater, others migrate from the ocean to spawn in rivers. During spawning, females produce millions of eggs, known as caviar, which is highly sought after as a delicacy. The process of spawning can occur hundreds of miles inland in deep waters. Despite their size and resilience, sturgeons face significant threats due to fishing, pollution, and habitat loss. Conservation efforts are crucial to protect these ancient fish and their ecosystems, as many species are now considered endangered.
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Sturgeon
Sturgeons are the largest freshwater fish and may live 100 years or more, which makes them the longest-lived fish. People call the roe, or eggs, from sturgeon "caviar" and consider it a delicacy to eat. Sturgeon means "stirrer" and comes from the fish's stirring the mud as it forages for food.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Acipenseriformes
Family: Acipenseridae
Genus: Various (see below)
Species: Various (see below)
While some sturgeon remain in freshwater lakes and rivers all their lives, others live in the northern oceans and seas but return to freshwater to breed.
Members of this family are impressive for their size and life spans. These fish may grow from 3 to 20 feet (one to six meters) long and weigh from 300 to over 1,000 pounds (135 to over 450 kilograms).
Sturgeons have heavy, rounded bodies with large scutes. Scutes are bony plates in five rows along their bodies, which may be black, grey, white, or olive. Each fish has a dorsal (back) fin slightly in front of its large, pointed tail. An anal fin grows near the tail, from the bottom of the body, and a pelvic fin lies a little farther forward, also on the bottom of the sturgeon's body. Two large pectoral fins rest below and just behind the gills. From their pointed snouts hang four sensitive feelers called barbels. These help the fish detect prey in the water near the bottom. The toothless mouth extends forward like a tube to suck in any food which the barbels detect.
Sturgeons forage for food along the bottom of the sea, lake, or river. They mainly eat invertebrates, or creatures without backbones, such as mollusks, shrimp, snails, and worms. Some also eat sand eels, gobies, clams, crayfish, and other small fish.
Because of their size and tough scutes, sturgeons face few natural enemies. Sometimes sea lampreys attach themselves to adults and feed on their blood and tissue, which may kill them. Fishing, pollution, and obstacles that prevent them from spawning in rivers and lakes are a greater threat to sturgeons. Females produce great quantities of roe, or eggs, which people call caviar and eat as a delicacy. One record-size Beluga sturgeon, which weighed 2,200 pounds (1,000 kilograms) and was 13 feet (four meters) long, yielded nearly 400 pounds (180 kilograms) of caviar and 1,500 pounds (670 kilograms) of meat. This same fish was at least 75 years old. Sturgeons have been caught for their eggs, meat, scutes, and oil.
Spawning, or the laying and fertilizing of eggs, occurs in the spring and summer, depending on the location and species. The fish make spawning runs, or migrate, from their homes to spawning grounds. Some species remain in freshwater the entire year, while others return hundreds of miles (kilometers) to freshwater from the sea. Spawning grounds may be hundreds of miles (kilometers) inland and are usually around 20 feet (six meters) deep. Those fish that migrate from the sea are said to be anadromous. Some species spawn every year. All species stop feeding when they are running and spawning. Females produce millions of eggs that stick to vegetation and stones until they hatch after 8 to 15 days. The adults return to their homes after spawning. The fry, or young, of saltwater species, swim to the sea after three years. After five years of growth, sturgeon fry is around 20 inches (50 centimeters) long. Males are fully grown after seven to nine years, and females can spawn for the first time after 8 to 14 years.
These large, heavy fish may live 100 years or more. The record age is a 154-year-old beluga sturgeon caught in 1926. Most sturgeons live 50 to 60 years.
Species include:
Atlantic sturgeon Acipenser oxyrhynchus
Baltic, or common, sturgeon Acipenser sturio
Beluga, or Russian sturgeon Huso huso
Green sturgeon Acipenser medirostris
Kaluga sturgeon Huso dauricus
Lake sturgeon Acipenser fulvescens
Pallid sturgeon Scaphirhynchus albus
Shortnose sturgeon Acipenser brevirostrum
Shovelnose sturgeon Scaphirhynchus platorynchus
Sterlet Acipenser ruthenus
White sturgeon Acipenser transmontanus
Bibliography
Dewey, T. "Acipenseridae." Animal Diversity Web, animaldiversity.org/accounts/Acipenseridae. Accessed 15 May 2024.
"Sturgeon." A-Z Animals, 31 Mar. 2023, a-z-animals.com/animals/sturgeon. Accessed 15 May 2024.
"Sturgeons." World Wildlife Fund, wwf.panda.org/discover/our‗focus/freshwater‗practice/freshwater‗inititiaves/sturgeon‗initiative. Accessed 15 May 2024.