Finding salmon in open water

The Great Lakes hold vast expanses of cold, clear water that salmon roam in search of prey. An understanding of how salmon and baitfish relate to edges in open water can help anglers narrow their search for hungry fish.

Michigan Sea Grant's YouTube channel offers a number of videos for anglers, like Salmon in the Great Lakes! - Photo courtesy: Michigan Sea Grant
Michigan Sea Grant's YouTube channel offers a number of videos for anglers, like Salmon in the Great Lakes! - Photo courtesy: Michigan Sea Grant

Each fall, salmon return to Michigan rivers where they are easy to spot as they splash their way upstream through clear, shallow water. Rivers, however, provide very little food for large salmon, which do most of their feeding and growing in open waters of the Great Lakes.

The favorite prey of Chinook salmon is the invasive alewife, a small silvery fish related to saltwater herrings. Alewife first invaded Lake Michigan at a time when predator populations were in decline due to another exotic invader—the sea lamprey, a primitive parasitic fish. A single adult lamprey can kill up to 40 pounds of trout and salmon during its lifetime.

With no predators left to eat them, alewife populations exploded. As they depleted their own food sources, alewife became susceptible to mass die-offs that littered the beaches in the early 1960s. Non-native Chinook salmon, coho salmon, steelhead, and brown trout were stocked along with native lake trout to take advantage of abundant prey and restore balance to the system.

The goal of fisheries managers who made the decision to stock salmon was to create a world-class sport fishery. Fishing for salmon in open waters of the Great Lakes is much different than fishing in inland lakes, and it took some time for specialized techniques to evolve.

Anglers can usually find inland fish, like bass and bluegill, near obvious structure. Breaklines formed by drop-offs, weed edges, and sunken logs provide good places to drop a lure. In much of the Great Lakes, this type of physical structure is not available. Even where it is available, salmon often prefer to hunt for prey in vast expanses of open water. Open water also has its edges, though.

Anglers use the CoastWatch website to find temperature breaks where baitfish and salmon congregate. Some of the best fishing occurs when upwelling currents bring cold water near shore in mid-summer. Fluctuations can be dramatic as temperatures drop by 20 or more degrees over the course of a day. Great Lakes current animations can also be found, online, to help plan a day of fishing. Powerful currents influence fish location in the Great Lakes, and anglers sometimes key in on edges where two currents meet.

Salmon usually prefer cold, clear water; but there are times when they will feed in or around plumes of warm, muddy river water. The warm river water floats on top of cold lake water, forming an edge that salmon and steelhead patrol. Trolling a lure along this edge can be a good way to attract the attention of a hungry salmon, but getting a follow is sometimes much easier than provoking a strike.

For more on catching salmon in open water see “Catching salmon in open water” from Michigan State University Extension.

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