Lake Sturgeon

Also called the rock sturgeon, this strange-looking, laid-back, long-lived fish hasn’t changed much since the Pleistocene epoch. Its body sports dinosaur-like scutes, and like a shark, its skeleton is made up mostly of cartilage. Despite its rough looks, its flesh and roe are delectable, and overfishing almost caused its extinction.

5 Amazing Facts About the Lake Sturgeon

• Males are ready to reproduce when they’re between 8 and 22 years old, but females are ready when they’re between 14 and 33.
• The lake sturgeon is considered North America’s largest freshwater fish and can grow to over 7 feet long. Still, it can’t hold a candle to the beluga sturgeon. This is the largest of the sturgeons and can grow over 20 feet long and weigh over a ton.
• The lake sturgeon has sensitive barbels on the end of its snout. These barbels help it find food in the gravelly bottom of the lake that is its habitat.
• It doesn’t have teeth.
• Its pupils are shaped like diamonds. This makes it unique among all the animals.

Classification and Scientific Name

The scientific name of the lake sturgeon is Acipenser fulvescens. Acipenser is Latin for “sturgeon”, and fulvescens is Latin for “yellowish.” There is only one species of this fish and no subspecies.

Appearance

The lake sturgeon has a long body and a long, paddle-like snout with sensitive barbels at its tip. There are five rows of bony plates along its body. One row is on its back, two are on its side, and two are on the sides of its belly. There are also scales in the spaces between these scutes, and its ventral mouth is made to suck up food it finds on the bottom of its watery habitat. This behavior causes some biologists to classify the sturgeon as an omnivore as opposed to a carnivore.

The lake sturgeon can grow to over 7 feet long and weigh over 300 pounds. It is gray or dark olive above and white or yellowish below. Its dorsal, pelvic, and anal fins are at the back of its long body near its tail. The tail is heterocercal, which means the upper lobe is bigger than the lower lobe and contains part of the fish’s spine.

Distribution, Population, and Habitat

Though it was abundant until the early 20th century, overfishing, pollution, and the damming of its rivers caused lake sturgeon populations to collapse. Recent estimates suggest there are around 140,000 lake sturgeon, and efforts are ongoing to further increase their numbers. The lake sturgeon’s current global conservation status is Endangered according to the IUCN Red List.

The fish’s habitat includes rivers as well as lakes, and it’s found from Hudson Bay and south to the Mississippi River basin. There are also populations in the Great Lakes, especially Lake Michigan.

Predators and Prey

Basically, the lake sturgeon eats anything that it sucks into its mouth. Despite the fish’s great size, its food items are usually very small animals such as insect larvae, snails, much smaller fish, and crayfish. The lake sturgeon is also unusual in that it has taste buds on the outside of its mouth.

An adult lake sturgeon is too large to be preyed on by any other freshwater fish save the lamprey. This gruesome, eel-like creature attaches itself to the fish, cuts a hole in it with its concentric rows of teeth, and feeds on its bodily fluids.

Reproduction and Lifespan

It can take decades for a lake or rock sturgeon to reach sexual maturity, and then it can go without breeding for many years. This reproductive behavior is part of what led to the collapse of its numbers over the 20th century.

When it is time to breed, the fish migrate toward lake shores and fast streams with gravelly or pebbly bottoms. This happens from April to June. The female can lay as many as 350,000 tiny eggs at a time in water that’s between 18 and 19.6 feet deep and 55 to 64 degrees Fahrenheit. During the breeding season, she can lay between two and three million eggs. The male fertilizes them externally, then both parents go back to where they came from. The eggs are found in a ball of jelly that keeps the current from washing them away, and they hatch in about six days. The larvae grow quickly, but it still takes them about 20 years before they are breeding size. After that, the fish grows very slowly.

Female sturgeons grow to be larger than males and tend to live longer. They can live as long as 150 years and may go 4 to 9 years between breeding. Males can live up to 55 years and typically breed every 1 to 2 years, with frequency sometimes increasing as they age.

Fishing and Cooking

Lake sturgeon used to be considered nuisance fish because they damaged fishing equipment. Then, people discovered that their flesh was not only good eating, but their eggs, called caviar, tasted good as well. Isinglass is also made from the sturgeon’s spine and swim bladder, and its oil is used for fuel.

Population

Because it was such a choice edible, and thanks to pollution and damming its rivers, the lake sturgeon became endangered. Efforts to rehabilitate the species have allowed its numbers to grow to around 140,000, even as female sturgeons are capable of producing millions of eggs during the breeding season.