Reference__2_-_Soo_Explore_the_Rapids_Exhibit.pdf

Explore the Rapids and Find the Fish!

The waters of the St. Marys River north of the Soo Locks are one of only two existing gravel bed rapids spawning areas in the river and a vital part of the lifespan of several fish species. The fast-flowing water draws fish here for spawning and provides oxygen to eggs and small fry on the riverbed.

A gated dam, or compensating works, regulates the amount of water entering the rapids from Lake Superior. In 2016 the U.S. Army Corps of Engineers through the EPA’s Great Lakes Restoration Initiative began work to automate these gates. This project allows them to open slowly, over several hours or even days. As a result, the spawning grounds will not be scoured by the sudden rise of water from rapid gate movements.

TOUCH THE SCREEN to explore the rapids and find the fish.

Touch the targets to find the fish!

Exhibit funded by Engineering with Nature

Whitefish Island

Since long before Europeans arrived in this area, native peoples encamped here every summer to gather the abundant fish found in the rapids. This island within the borders of Canada belongs to the Batchewana First Nation of Ojibwe but the public is welcome to take advantage of trails on the island, several river overlooks and fishing access on the north shore of the rapids.

A staple of the Native diet and later the foundation of the Great Lakes commercial fishery were Lake Trout and the Whitefish the island is named for.

Touch to learn more about Lake Trout

Touch to learn more about Whitefish

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Lake Trout

Average Size: 9-10 pounds, Michigan Record: 49 inches, 61.5 pounds Lifespan: 25 years or more

The largest native trout species on the Great Lakes, Lake trout spend most of their lives in the cooler, deep waters of the Great Lakes, coming in to shallow reefs and shoals to spawn in the fall. Their young will stay along the bottom for several months, emerging from the protective gravel in the late spring. Trout were once common throughout the Great Lakes but their populations were hard hit by commercial over fishing and the parasitic Sea Lamprey. Populations have been rebounding after restocking efforts, regulation of commercial fishing and work to control lamprey populations. It is not known if Lake Trout spawn in the rapids, but they are still caught here.

Lake Whitefish

Average Size: 17-22 inches, 1.5-4 pounds Michigan Record: 31.75 inches, 14.28 pounds Spawn: November/December Lifespan: up to 25 years

A native fish to the Great Lakes and member of the salmon family, Lake Whitefish is one of the most popular table fish in this region. They formed an important food source for Native peoples and were the foundation of Michigan’s commercial fish industry for years.

Overfished in the past, Whitefish populations are recovering through careful fisheries management and efforts to restore and preserve their habitats – like the project here at the locks. Whitefish like to spawn in rock or sand bottomed lakes, so it seems unlikely that they spawn here, but young fish have recently been seen leaving the rapids in the late summer.

Lake Whitefish were historically common in the rapids.

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Base of the Rapids

At the base of the rapids the water depth quickly drops from five feet or less to up to 20 feet deep. This deep water is an important staging area for fish preparing to enter the rapids to spawn, its depth protects them from predators while they rest in its slower moving water. Predatory fish also lurk in the deep, darker waters to feed on fish leaving the rapids.

Muskellunge (Muskie) and Walleyes are two of the fish frequently caught in this area below the rapids.

Touch to learn more about Muskellunge

Touch to learn more about Walleye

Muskellunge (Muskie)

Average Size: 5-36 pounds, 28-48 inches Michigan Record: 58 pounds, 59 inches Lifespan: Up to 20 years

Though Muskellunges or “Muskies” don’t spawn in the rapids, instead laying their eggs in vegetation and wood in shallow water, they are an important part of the rapids’ food web as a predatory fish. The second largest of the Great Lakes fish, reaching up to 48 inches long and up to 36 pounds, they lurk in rock outcrops and ambush other fish, small reptiles and birds. Muskie are often caught by fishermen in slower back waters of the rapids.

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Walleye

Average Size: 3 pounds Michigan Record: 35 inches, 17.19 pounds Spawn: March/April/May Lifespan: 10-12 years, but up to 20 years

Walleye spawn over rock shoals in rivers or lakes in the spring, and though spawning activity has not been seen here, they are regularly caught in the river below the rapids. They are widespread through Michigan with all but 7 counties categorized as “Better waters” for catching walleye according to the Michigan DNR. A good fighter, walleyes are active year round making them a popular fish with sport fishermen.

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Compensating Works

This dam stretching across the head of the rapids was finished in 1921, to regulate the water flowing out of Lake Superior into the lower lakes. An international agency, the Lake Superior Board of Control determines the settings for opening or closing its gates. In the past when the gates opened it created a rush of water that could flush away fish eggs and small fry. When the gates closed, fish could be trapped in the rapids as the water quickly receded. Congressionally authorized funds from the EPA’s Great Lakes Restoration Initiative (GLRI) provided monies for automating these gates to raise or lower them over several hours or even days to slow water level changes reducing the impact on spawning fish and nursery beds.

The fast moving water flowing through the gates attracts several species of fish including Lake Sturgeon, and Sea Lamprey.

Touch to learn more about Lake Sturgeon

Touch to learn more about Sea Lamprey

Lake Sturgeon

Average Size:

Michigan Record: 87 inches, 193 pounds (documented up to 300 pounds) Spawn: May/June/July Lifespan: up 150 years

The oldest fish species in the Great Lakes, Lake Sturgeon, is a threatened species in Michigan. Once living throughout the lakes with over 4 million pounds harvested in Michigan in 1880, the current population is only about 1% of what it once was. Overfishing, habitat changes and its slow reproductive cycle have made recovery difficult. Females don’t spawn until they are 14-33 years old and then only reproduce once every 3-4 years.

Sturgeon need rocky riverbeds, with fast flowing water, like the St. Marys Rapids to spawn.

Returning to their native rivers, females release eggs over the rocky bottom where they settle and form clusters hatching in 3-5 days. The longest lived fish in the Great Lakes, Lake Sturgeon grow very slowly taking up to 20 years to reach maturity.

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Sea Lamprey

Average Size: 18-24 inches

Despite its appearance, the Sea Lamprey is not an eel, but a jawless parasitic fish which can kill up to 40 pounds of fish in its lifetime. The adult Lamprey uses its disk shaped mouth to attach itself to a fish then bores a hole through the scales and skin using its sharp tongue to feed on the fish’s blood and fluids. An enzyme secreted by the lamprey prevents the wound from healing so fish that survive an attack often die from infection.

The sea lamprey is a non-native invasive species that has spread through the Great Lakes since its 1835 discovery in Lake Ontario. With no natural predators in the Great Lakes, Sea Lamprey wreaked havoc on native fish like Whitefish, and Lake Trout leading to the collapse of the commercial fishery on Lakes Michigan and Huron in the 1940s. These native fish are slowly rebounding and federal, state and private agencies are working together to control Sea Lamprey populations. Here at the Soo Locks the U.S. Army Corps of Engineers works with the U.S. Fish and Wildlife Service to monitor and trap Sea Lampreys.

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