Lake Michigan, a vast freshwater expanse, supports a diverse array of fish species, contributing to its rich ecosystem and providing recreational opportunities. Understanding the fish inhabiting its waters offers insight into the lake’s ecological dynamics.
Popular Game Fish
Chinook Salmon, or “King Salmon,” are a highly sought-after game fish in Lake Michigan, known for their large size (averaging 10-30 pounds, some exceeding 40). They are iridescent green to blue-green with a distinctive grey or black mouth. Anglers find them in deep open water during summer and near river mouths in fall for spawning.
Coho Salmon, or “Silver Salmon,” typically weigh 2-10 pounds. They are silver with a dark blue-green back and black spots on the upper tail fin. Introduced to control invasive alewife populations, Coho provide fast-paced action for anglers, especially nearshore in spring.
Lake Trout, or “Mackinaw,” are deep-water inhabitants, generally ranging from 3 to 12 pounds. They are found in the colder, deeper sections of the lake.
Steelhead, a migratory rainbow trout, average 6-12 pounds. They spend most of their lives in the lake, returning to tributary rivers to spawn from February to April. Unlike Pacific salmon, they do not die after spawning. Steelhead are known for their strong fights and leaping ability.
Brown Trout, introduced in the 1800s, often reach 10-20 pounds. They display a golden coloration with red and black spots, and are known for their wary nature. Brown trout are typically found in shallow water weed beds, rocky areas, and near stream outlets, spawning in fall in tributaries.
Yellow Perch, 6-12 inches, are common throughout the lake in both shallow and deep waters. They are an important prey species for larger fish and valued for their palatable meat.
Walleye, characterized by their greenish color and large, dark eyes, typically weigh 2-5 pounds but can grow up to 20 pounds. They are often found in both deep and shallow areas, preferring low-light conditions.
Significant Native Species
Lake Whitefish are a schooling species typically inhabiting depths up to 200 feet. Juveniles are found along shorelines, while adults move to deeper regions, serving as a food source for predatory fish.
Cisco, or lake herring, are a salmonid species that once formed a substantial part of the Great Lakes’ commercial fishery and served as a primary food source for top predators like lake trout. These fish filter zooplankton, playing a unique ecological role. Cisco populations have declined due to historical overfishing, habitat degradation, and invasive species.
Invasive Species Impacting Fish Populations
Non-native species have significantly altered Lake Michigan’s ecosystem, impacting native and game fish populations. The Alewife, a forage fish introduced in the 1960s, became prominent as native cisco populations declined. While serving as prey for salmon, alewives contain high levels of thiaminase, which interferes with trout and salmon reproduction, and they also prey on larval fish.
The Round Goby, an aggressive bottom-dwelling fish native to Eurasia, arrived in the Great Lakes via ship ballast water in the 1990s. This species reproduces rapidly (up to six times per summer) and outcompetes native fish for food. Round gobies also consume the eggs of important game fish, including lake trout, sturgeon, walleye, and bass. Their ability to thrive in poor water quality gives them an advantage over many native species.
The Sea Lamprey, originally from the Atlantic Ocean, entered the Great Lakes through the Welland Canal in 1919. This parasitic fish uses a suction-cup mouth with sharp teeth to attach to other fish, feeding on their blood and fluids, often resulting in the host’s death. Before control measures, sea lampreys caused dramatic reductions in fish populations, killing an estimated 100 million pounds annually. Control efforts have since reduced populations by 90-95%, allowing for some fishery recovery.