Lake Michigan, one of the North American Great Lakes, supports a rich array of aquatic life. Its deep, cool waters provide diverse habitats for many fish species, ranging from smaller forage fish to impressive predators. This dynamic ecosystem includes both native and introduced species, creating a complex underwater world.
The Reigning Giant of Lake Michigan
The Lake Sturgeon is the largest fish species found in Lake Michigan. These ancient fish can grow to remarkable sizes, with some individuals reaching up to 8 feet in length and weighing as much as 300 pounds. Specimens caught today typically measure between 3 and 6 feet and weigh 30 to 100 pounds. Lake Sturgeon are long-lived, with males averaging 55 years and females living significantly longer, sometimes reaching 80 to 150 years.
These fish are primarily bottom feeders, using their sensitive barbels to locate prey. Their diet consists of a variety of small invertebrates, including snails, crustaceans, aquatic insects, and mussels. Lake Sturgeon inhabit nearshore areas, typically in water depths of 15 to 30 feet, but undertake significant migrations. For spawning, they move into fast-flowing rivers, laying eggs on gravel and rocky substrates.
Despite their longevity, Lake Sturgeon are slow to mature, with males reaching reproductive age around 15 years and females between 20 and 25 years. Females only spawn once every four years on average. Historically, Lake Sturgeon were abundant in the Great Lakes, but overharvesting in the 1800s and early 1900s, coupled with habitat loss from dam construction and pollution, led to a severe decline in their populations. The species has been designated as threatened in Michigan since 1994, and conservation efforts are underway to restore their numbers, estimated to be less than 1% of their historical abundance.
Other Impressive Large Fish
While the Lake Sturgeon holds the title for size, Lake Michigan is home to several other large and notable fish species.
Chinook Salmon
The Chinook Salmon, also known as King Salmon, is a popular game fish. These salmon typically average about 3 feet in length, weighing between 10 and 20 pounds, though some exceed 30 pounds. Chinook Salmon were introduced to Lake Michigan in the 1960s to help control the abundant alewife population. They spend their lives in the open waters, feeding on smaller fish like alewives, herring, and smelt, before migrating into tributary rivers to spawn and then die.
Lake Trout
Lake Trout, a native species to Lake Michigan, also attain considerable sizes and are sought after by anglers. These long-lived fish can weigh up to 40 pounds. Lake Trout prefer the cold, oxygen-rich depths, often residing in waters 66 to 197 feet deep. They spawn over rocky shoals or in tributary streams. Once severely impacted by invasive sea lampreys and overfishing, Lake Trout populations are now showing signs of recovery due to sustained stocking programs and increasing natural reproduction.
Walleye
The Walleye, recognized for its distinctive glassy eyes, is another large species found in Lake Michigan. Walleye typically measure between 2.5 and 3 feet in length and can weigh up to 20 pounds. They prefer cooler, quieter waters and are often found near structured areas such as rocky breakwalls and submerged vegetation. Walleye are most active during dawn and dusk, feeding on smaller fish, insects, and crustaceans. Healthy Walleye populations exist in specific areas, such as Green Bay, often supported by natural reproduction.