Lake Superior, the largest freshwater lake by surface area globally, supports a diverse aquatic community. Often associated with cold-water species, it also hosts populations of salmon, fish typically linked to oceanic environments. The presence of these salmon in Lake Superior raises questions about their origins and their role within this unique inland ecosystem.
Salmon Species Present
Several salmon species inhabit Lake Superior, although none are native to the Great Lakes. Chinook salmon, also known as King salmon, represent the largest of the non-native salmonids in the lake. While they can grow to over 10 pounds, typical catches range from 3 to 4 pounds, with some exceeding 30 pounds in the Great Lakes. Coho salmon, or Silver salmon, are smaller, commonly weighing between 1.5 to 3 pounds, though they can reach up to 5 pounds. Pink salmon, often called “humpies” due to a male’s breeding season hump, are the smallest, usually over a pound. Atlantic salmon are also present, though less abundant, and can reach up to 10 pounds, with larger specimens reported.
Pacific salmon species (Chinook, Coho, Pink) were introduced to Lake Superior and now reproduce naturally in its tributaries. Atlantic salmon, historically native to Lake Ontario, are also an introduced species. All these introduced salmon feed in the main lake until they reach sexual maturity, then migrate upstream to spawn.
How Salmon Arrived in Lake Superior
Salmon were introduced to Lake Superior primarily through deliberate stocking programs by fisheries management agencies. Early attempts to establish Chinook salmon in the Great Lakes date back to the late 1800s, but these efforts failed to establish self-sustaining populations. A significant introduction effort began in the mid-1960s, led by the Michigan Department of Natural Resources, which successfully established Chinook and Coho salmon in Lake Michigan.
These stocking initiatives aimed to create a robust sport fishery and to control burgeoning populations of invasive prey fish. Alewives, an invasive herring species, had become abundant in the Great Lakes, and salmon were introduced to prey upon them. The Minnesota Department of Natural Resources, along with Wisconsin and Ontario agencies, followed Michigan’s lead, introducing Chinook salmon in 1974, Coho salmon in 1969, and Atlantic salmon in 1980. Pink salmon fry were inadvertently stocked in Lake Superior in 1956 and establishing a naturalized population. Some stocking programs, like Minnesota’s Chinook, have been discontinued due to successful natural reproduction or re-evaluation, but the initial introductions laid the foundation for current populations.
Ecological Impact and Angling Opportunities
Introduced salmon have integrated into Lake Superior’s food web as predators. They consume various smaller fish, with rainbow smelt and alewives being significant components of their diet. Chinook salmon, for example, rely heavily on alewives as a food source in the Great Lakes. This predatory role has contributed to the control of these invasive prey species. The presence of these salmon, particularly during spawning runs, also influences tributary streams by introducing marine-derived nutrients from their decomposing carcasses.
Beyond their ecological role, salmon provide considerable angling opportunities in Lake Superior. Anglers can pursue Chinook, Coho, and Pink salmon, as well as Atlantic salmon, year-round. Trolling is a popular method for catching salmon in the vast open waters of Lake Superior, especially during summer months when fish are scattered. Shore fishing is effective for Coho and Pink salmon, particularly in the fall and spring near river mouths. Salmon fishing contributes to the economic vitality of communities surrounding Lake Superior.