In the United States, the largest freshwater fish is the white sturgeon, a behemoth that can attain lengths of 20 feet and weigh more than 1,500 lbs. White sturgeon live in river systems, so this species does not qualify as the largest species found in lakes on the continent. That honor falls to other species that pale in comparison when you put them up against the white sturgeon, but fish such as the lake sturgeon, muskellunge and lake trout are still big fish.
The lake sturgeon (Acipenser fulvescens) can reach lengths of more than 7 feet and weigh 300 lbs. Found in lakes in states as far north as New York and Minnesota and as far south as Alabama and Louisiana, the lake sturgeon can live in rivers as well as lakes. Lake sturgeons are a primitive-looking species, with an elongated body protected by five rows of scutes, or bony plates. The lake sturgeon's big mouth, shaped like a cone, possesses four appendages (barbells) that help the fish find creatures like leeches, clams and snails on the bottom of the water. The lake sturgeon can live for many years. According to the New York State Department of Environmental Conservation, one caught in 1953 was 154 years old. Lake sturgeons mature slowly, with a male requiring as long as 19 years to achieve sexual maturity. Lake sturgeons are a threatened species throughout North America because overfishing, pollution and loss of habitat have depleted their populations.
The muskellunge (Esox masquinongy) is the Pike family's largest member and a fish that can grow larger than 50 inches and weigh well over 50 lbs. The muskellunge's natural range is from Tennessee to the middle of Ontario, Canada, in terms of north and south and from as far east as New York to as far west as Minnesota. The muskellunge is elongated and streamlined, according to the Fondriest Environmental website, and this aggressive predatory species has rows of sharp teeth. The fish has great value as a game fish in many states, and the muskie has a reputation as being difficult to catch. Muskellunge typically inhabit the shallows of lakes and have a varied diet that includes fish, ducks, snakes and, on occasion, each other.
The lake trout (Salvelinus namaycush) is the largest freshwater fish found in lakes in many northern states, such as Michigan and Alaska. The lake trout can reach weights in excess of 50 lbs., as evidenced by state records such as the Michigan lake trout that weighed over 61 lbs., according to the Michigan Department of Natural Resources and Environment website. Lake trout prefer cold water, in the range of 45 to 55 degrees F, which usually is at depths greater than 100 feet in most lakes. Lake trout will prey on other fish, such as ciscoe and alewives, as well as crustaceans and bugs. Pollution and a parasitic creature called a sea lamprey affect lake trout populations. The lake trout can live for more than 20 years in some cases.