Lake Michigan supports a thriving freshwater fishery, home to various salmon species that contribute to its ecosystem and offer significant recreational opportunities.
The Primary Salmon Species
Four primary salmon species are found in Lake Michigan: Chinook, Coho, Atlantic, and Pink salmon.
Chinook Salmon
Chinook salmon, often called “King salmon,” are the largest and most sought-after in Lake Michigan. They have a silvery body with black spots on their back and both tail fin lobes. Their gums are black at the base of the teeth. Mature adults commonly weigh 10 to 20 pounds, with some exceeding 30 pounds.
Coho Salmon
Coho salmon, known as “Silver salmon,” are smaller than Chinooks. They have a silver body with a dark blue-green back and black spots on their back and upper tail fin lobe. Unlike Chinook salmon, Coho salmon have white or grayish gums. An average Coho in Lake Michigan weighs 2 to 6 pounds.
Atlantic Salmon
Atlantic salmon are less common but recognized for their fighting ability. They have black spots above their lateral line and often display two or three larger spots on their gill cover. Their caudal fin may be slightly forked, and pectoral fins are dark. Atlantic salmon in Lake Michigan average 8 to 10 pounds.
Pink Salmon
Pink salmon, also called “Humpback salmon” due to the prominent hump developed by spawning males, are the smallest Pacific salmon in the Great Lakes. They are silver with large oval black spots on their back and tail. Mature pink salmon weigh two to three pounds and measure around 20 inches.
Their Journey to Lake Michigan
Most salmon species in Lake Michigan were intentionally introduced, not native. These introductions began in the mid-20th century to address ecological imbalances and create a sport fishery.
Pacific salmon like Coho and Chinook were introduced to Lake Michigan starting in the 1960s. This aimed to control alewives, an invasive species that entered the Great Lakes via the St. Lawrence Seaway. Alewives caused significant ecological issues like massive die-offs that littered beaches.
Initial stocking of Coho salmon occurred in 1966, followed by Chinook salmon in 1967. These introductions proved successful, as salmon readily fed on alewives, managing their population.
Pink salmon arrived in the Great Lakes accidentally. Introduced into a Lake Superior tributary in 1956, a self-sustaining population developed and spread throughout the Great Lakes, reaching Lake Michigan. Atlantic salmon were also introduced for fishing, though they did not establish widespread breeding populations; some migrated from Lake Huron.
Ecological Influence and Management
Introduced salmon species have significantly influenced Lake Michigan’s ecosystem as top predators. Their presence requires ongoing management efforts by state and federal agencies to sustain populations and ecological balance.
As top predators, Chinook and Coho salmon control populations of smaller forage fish, like alewives and smelt. This predatory pressure helps regulate the food web disrupted by invasive species. Salmon consumption of alewives has been a key factor in mitigating ecological problems caused by their population boom.
Management largely involves consistent stocking programs. While some natural reproduction occurs, especially for Chinook salmon, hatchery-raised fish are regularly released to supplement wild populations and support the sport fishery. Stocking efforts are critical because many introduced species have limited natural reproductive success in Lake Michigan’s tributaries.
Fishing regulations are another management component, designed to ensure sustainable harvest and protect fish populations. These often include size and possession limits for anglers. Continuous monitoring and research help agencies adapt strategies to address changes in the lake’s ecosystem, like shifts in forage fish availability or the impact of other invasive species.