Acipenser oxyrinchus facts for kids
Quick facts for kids Acipenser oxyrinchus |
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| A. o. oxyrinchus | |
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Acipenser
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oxyrinchus
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The Acipenser oxyrinchus, also known as the Atlantic sturgeon, is a fascinating type of fish. It belongs to the sturgeon family. This species is known for its long migrations between fresh and saltwater. It is also famous for its impressive size.
Contents
About the Atlantic Sturgeon
The Atlantic sturgeon has two main types, called subspecies:
- The Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus.
- The Gulf sturgeon, Acipenser oxyrinchus desotoi.
These fish mostly eat small creatures like worms, crabs, and snails. They are known to swim up rivers to lay their eggs. Atlantic sturgeon are found mainly in Canada and the United States. A smaller group lives in northern Europe, especially around the Baltic Sea. This European group is in great danger of disappearing.
Sturgeon can live in both warm and mild climates. You can find them in salty ocean water or fresh river water. Sadly, this species is considered vulnerable. They are at risk because of things like dam building and water removal.
What They Look Like
Atlantic sturgeon are truly big fish! They can grow up to 14 ft (4.3 m) long. Some can weigh as much as 800 lb (360 kg). These amazing fish can live for about 60 years. Their bodies are usually bluish-black or olive-brown on top. Their sides are lighter, and their bellies are white.
How They Behave
Sturgeon are a type of fish called anadromous. This means they live in the ocean but swim up rivers to spawn. They usually live alone or in small groups.
They prefer shallow waters near the coast. You can find them in coastal areas and river mouths. They like soft, muddy bottoms in the sea. They can live in waters as deep as 160 ft (49 m). Adult sturgeon travel long distances in the ocean. Young sturgeon, called juveniles, stay in fresh or slightly salty water. They live there until they are two to five years old.
Amazing Migrations
Sturgeon make long journeys up rivers to lay their eggs. This is called spawning. For example, sturgeon from the Gulf of Mexico swim into rivers in the spring. Many are seen in March and April. They travel into rivers like the Suwannee River in Florida.
After spawning, they swim back downstream. Atlantic sturgeon do not need to travel far to find places for their young. Some sturgeon travel at night, while others travel during the day. In the summer, they stay in certain parts of the rivers. In the late fall, they leave the rivers and go back to the ocean.
Sturgeon migrate into freshwater in early spring. They move back to saltwater in the fall. The timing of their travel depends on water temperature changes. Studies show that sturgeon in the Gulf of Mexico gain weight in the ocean. They then lose some weight while in the rivers.
Spawning Habits
Sturgeon eggs, embryos, and larvae survive best in water temperatures between 15 to 20 °C (59 to 68 °F). If the water gets too warm, like 25 °C (77 °F) or higher, many young fish may not survive. For spawning to happen, the water temperature needs to be above 17 °C (63 °F). Spawning usually lasts about nine to twenty-three days. It can continue longer if the water stays cool enough.
Baby sturgeon, called embryos, hide under rocks after hatching. They do not move much at first. They stay in the freshwater spawning areas. Later, larvae and young juveniles slowly swim downstream. This helps them spread out. The entire river section below the spawning site becomes a nursery for these young fish.
Sturgeon often use the same places to spawn each year. These spots usually have gravel on the bottom. They also have calm areas where the water swirls. The water's pH is slightly basic, and it has a certain amount of calcium. Eggs are laid in a small area and do not spread far. The fish only start to spread widely when they become larvae and juveniles.
Body Color and Travel
Scientists have noticed that the color of a sturgeon's body might be linked to how it travels. Young embryos are light in color and do not migrate. But older larvae and adult sturgeon are dark. These darker fish do migrate. This pattern is seen in many sturgeon species. The reason for this is not fully clear. It might help them adapt to migration and blend in with their surroundings.
What They Eat
When sturgeon are in freshwater, they mainly eat soft-bodied worms, insects, and snails. When they move from river mouths to the sea, they eat small crustaceans. These include tiny shrimp and other small creatures living on the seafloor. Adult sturgeon also eat dead plant and animal matter. Overall, sturgeon are known for eating crustaceans, worms, and mollusks.
Young sturgeon, called larvae-juveniles, search for food on the river bottom. However, food can be scarce there. So, many learn to "drift feed." They hold still in the water and wait for food to float by. Larger sturgeon might be dominant when competing for food.
Where They Live
Atlantic sturgeon are found all along the Atlantic coast of the United States. Because they spread out so much, there are many different groups of sturgeon.
Generally, sturgeon live in the mild waters of the northern half of the world. Gulf of Mexico sturgeon are likely used to warmer water. Since sturgeon prefer cooler waters, they will look for cool springs when temperatures rise. These springs act as safe spots until the water cools down again.
Threats to Sturgeon
Sturgeon have certain traits that make them sensitive to human activities. These activities make it hard for their populations to recover. They mature late in life. Females only lay eggs every three to five years. Males spawn every one to five years. This is because they can live for a very long time.
The number of Atlantic sturgeon has dropped a lot because of too much fishing. In the late 1800s, there was a high demand for caviar. This led to too many sturgeon being caught. Today, only 22 of their original 38 spawning rivers still have healthy sturgeon populations.
Sturgeon are also often caught by accident in fishing nets. This is called "bycatch." Their habitats often overlap with coastal fishing areas. This puts them in frequent contact with fishing boats.
Effects of Low Oxygen
Low oxygen levels, called hypoxia, combined with high summer temperatures, can harm young sturgeon. This has been seen in places like Chesapeake Bay.
Hypoxia means there is not enough oxygen in the water. This can be very dangerous for fish. Often, the deeper parts of the water have less oxygen. If sturgeon cannot reach the surface for oxygen, it can be deadly. More frequent summer hypoxia has damaged many sturgeon nursery areas in the United States.
Conservation Efforts
Sturgeon populations have greatly decreased over the past centuries. Some even disappeared from the Baltic Sea in the late 1900s. Changes to rivers and barriers like dams affected their migration. Pollution also played a role.
Since 1996, efforts have been made to bring Baltic sturgeon back. Sturgeon from America are used because they are genetically similar. The goal is to reintroduce these sturgeon to their original spawning grounds. The organization NatureServe considers the species Vulnerable.
In 2012, the Atlantic sturgeon received special protection under the Endangered Species Act. This law helps protect animals that are at risk.
In 2022, the International Union for Conservation of Nature stated that sturgeon are "the animal group most at risk of extinction in the world."
