The Not-So-Great Lakes: Relentless Onslaught of Exotic Species
March-April 2008
This is the first in a series of five articles on major problems in management of the Great Lakes. As the earth’s single largest body of fresh water the Great Lakes have long been studied by citizen’s groups, and the federal, state and provincial governments that own or regulate its shoreline. Determining the heath of the huge ecosystem is a daunting task, and seemingly, always lagging behind the problems. That’s because it often takes years of observation to recognize changes or understand how the waters are responding to stress. This series addresses some of the issues citizens need to know about if the Great Lakes are to become great again.
In the 1960s, the exotics we of in the Great Lakes were pretty big and their impacts very noticeable. Adult sea lampreys—outrageously ugly, eel-like creatures—reached 17 inches in length and were as thick as the butts of fishing rods. The parasites latched on to lake trout and other game fish and did not let go until the fish was dead or at least emaciated. Surviving fish bear huge scars that fishermen and biologists alike learned to recognize from a distance. As a teenager, I caught many sea lampreys on hook-and-line. Like a lot of other Michiganders, I came to know sea lampreys “up-close and personal.”
Alewife, another species that entered the Great Lakes area via the St. Lawrence Seaway, were a little smaller, but also obvious to everyone who used the Great Lakes or its shoreline. The pale-colored fish died by the millions every year and washed up on beaches in stacks several feet high. Huge mounds of stinking, decaying alewife kept swimmers away from those beaches in late summer.
Government responses were also dramatic and easy to observe. A massive program to poison sea lampreys in their spawning streams was launched, and Pacific salmon, themselves exotics, were brought in to eat the alewife. You could watch it all happen, and it provided hope that these exotic species were going to be “under control.”
Today, we still have plenty of sea lampreys and alewife, and exotic species entering the Great Lakes arguably faster than when we were less enlightened. There are now 183 invasive species known to already be in the Great Lakes and a new species arrives on average every 28 weeks. Few of today’s newcomers swim in on their own through the St. Lawrence Seaway. Rather, they ride in on the hulls or in the ballast water tanks of ocean going ships. Among the more notorious are the zebra mussel and two small fishes—the round goby and the ruffe (pronounced as two syllables: ruff-ee). But the list also includes things we can hardly see such as the spiny water flea, the fishhook flea, and other zooplankton forms. Fishermen spot them fouling their lines, but most Michigan citizens aren’t aware of them. Instead of scarring fishes or making messes on beaches, the new breed of Great Lakes exotics mess up the food chain and affect the clarity of the water.
Problems associated with ruffe and gobies are not as dramatically apparent as with sea lampreys or alewife, but they are also detrimental. Ruffe and goby populations can grow rapidly, often resulting in less food and habitat for native species. Young ruffe eat the same food and compete for the same habitat as native yellow perch, walleye and a variety of other species. Because of this, ruffe can have a serious impact on perch and walleye fisheries without leaving external scars as a calling card. Gobies eat small fish and eggs and in low light conditions have a major competitive advantage over native fish such as darters and sculpins.
Zebra and quagga mussels, on the other hand, feed by filtering from the water large amounts of microscopic algae, which are an integral part of the Great Lakes’ food chain. They can kill native clams and crayfish by attaching to their bodies, increase aquatic plant growth by increasing water clarity, and compete with larval fish and other aquatic organisms for food. Zebra and quagga mussels have been blamed for so thoroughly clearing the Great Lakes water that plants such as cladophera (an algae) can now grow in much deeper water. When these plants break loose or die they roll up on beaches in piles of unsightly stinking vegetation. Besides environmental impacts, the mussels can clog water intake pipes and foul beaches and boating facilities. The mussels have now been transported to many inland lakes where they are causing further problems.
Some of the exotic zooplankton species are larger than native zooplankton species. In addition, they have long spines that make them hard for young fish to eat. If young fish are unable to consume enough of them, a shift in populations may occur with the exotic species replacing the native populations. This would leave less food for young fish and cause a decrease in native fish populations. They also eat smaller native zooplankton, which could also cause a decrease in available food for native fish.
Today, rather than attempt straight-forward but costly control programs, biologists talk about “integrated pest management,” and acknowledge that for today’s exotic species, the only effective strategy is prevention. Once ruffe, gobies, or the host of zooplankton, mussels, crayfish and other life forms become established you can’t control them. So, the emphasis has shifted to educating the public as to how to keep them out of inland waters, and on legislative action to stop the introduction of new species by requiring the treatment of ballast water in ocean-going ships.
The legal battle took an interesting turn last year when a federal court in California ruled that the Environmental Protection Agency could regulate the ballast water in ships. Michigan had already passed a law regulating ballast water in our state’s part of the Great Lakes. It took effect in January and requires discharge permits before any ballast water tanks are emptied. These legislative and court actions were long overdue, as many conservationists asserted. It is not a case of environment versus economics because regulating ballast water also makes good economic sense. Exotics threaten a $4 billion Great Lakes fishery.
The Michigan Wildlife Conservancy is an active member of the Healing Our Waters coalition, a collection of 90 local, state, Great Lakes Region, and national wildlife and environmental groups. This coalition is working toward a national solution to the discharge of saltwater ballast from foreign ships, the primary source of exotic species in the Great Lakes. This coalition is working toward a national solution to the discharge of saltwater ballast from foreign ships, the primary source of exotic species in the Great Lakes. The coalition advocates legislation that has been introduced in Congress to require treatment of all saltwater ballast entering the Great Lakes/St. Lawrence River system. Until this measure becomes law, the coalition has called for a ban on saltwater ships entering the Great Lakes. A ban may be the best strategy long term because recent research by University of Notre Dame biologists found eight species previously not found in the Great Lakes lining the outside hull of a ship. The ship was dry-docked in Ontario and originated in South America. That means merely treating ballast water might not be the total answer to preventing more exotic species from entering the Great Lakes.
Dr. Patrick Rusz
Director of Wildlife Programs
INVADERS!
Zebra Mussels
Zebra Mussels are native to the Ukraine and Russia. They were introduced into Lake St. Clair and Lake Erie in the mid-1980s and discovered in 1988. A transatlantic freighter coming from Eastern Europe is believed to have introduced them into North America when it dumped its ballast water in the Great Lakes. Since then, zebra mussels have continued to spread throughout all of the Great Lakes as well as the Mississippi, Tennessee, Hudson and Ohio river basins. They most likely will spread farther south and west.
Within 10 years of their discovery in Lake St. Clair, zebra mussels spread through a variety of pathways—including currents, bait buckets and recreational boats—into more than 100 inland lakes throughout the Lower Peninsula of Michigan. Veligers, as the free-swimming microscopic larvae of the zebra mussel are known, can drift downstream or be transported in water that accumulates in the bottoms of boats or in bilge pumps or bait buckets. Adults can attach to boat hulls, engines, aquatic plants or other objects that people move from lake to lake.
Round Goby
The round goby was discovered in the St. Clair River in 1990. It was most likely introduced in the late 1980s via ballast water of transatlantic freighters. The round goby is native to the Ukraine and Russian regions. The round goby is native to the Ukraine and Russian regions. By 1995, the round goby was found in Lake St. Clair, Lake Michigan, Lake Erie, Lake Superior and many tributaries to these lakes. Because of the round goby’s ability to adapt to a variety of water conditions, it has potential to spread throughout Michigan’s inland lakes.
Ruffe
The ruffe was introduced into Lake Superior in the mid-1980s and was discovered in the Duluth/Superior harbor in 1986. It became the most abundant fish in the area within a few years of discovery. This fish is native to Europe and Asia and was most likely transported to the Great Lakes in the ballast water of transatlantic freighters. In Europe, the ruffe is found in waters ranging from deep, cold and clear to shallow, warm and nutrient rich.
Spiny Water Flea (Bythotrephes cederstroemi), Fishhook Flea (Cercopagis penogi) and (Daphnia lumholtzi)
Spiny water flea has been found in all of the Great Lakes since the 1980s. Fishhook flea has been found in Lake Ontario since 1988. Daphnia lumholtzi was found in the Illinois River in 1995 and in Lake Michigan in 1999. It is likely that they were introduced into the Great Lakes through ballast water.
This is the first in a series of five articles on major problems in management of the Great Lakes. As the earth’s single largest body of fresh water the Great Lakes have long been studied by citizen’s groups, and the federal, state and provincial governments that own or regulate its shoreline. Determining the heath of the huge ecosystem is a daunting task, and seemingly, always lagging behind the problems. That’s because it often takes years of observation to recognize changes or understand how the waters are responding to stress. This series addresses some of the issues citizens need to know about if the Great Lakes are to become great again.
In the 1960s, the exotics we of in the Great Lakes were pretty big and their impacts very noticeable. Adult sea lampreys—outrageously ugly, eel-like creatures—reached 17 inches in length and were as thick as the butts of fishing rods. The parasites latched on to lake trout and other game fish and did not let go until the fish was dead or at least emaciated. Surviving fish bear huge scars that fishermen and biologists alike learned to recognize from a distance. As a teenager, I caught many sea lampreys on hook-and-line. Like a lot of other Michiganders, I came to know sea lampreys “up-close and personal.”
Alewife, another species that entered the Great Lakes area via the St. Lawrence Seaway, were a little smaller, but also obvious to everyone who used the Great Lakes or its shoreline. The pale-colored fish died by the millions every year and washed up on beaches in stacks several feet high. Huge mounds of stinking, decaying alewife kept swimmers away from those beaches in late summer.
Government responses were also dramatic and easy to observe. A massive program to poison sea lampreys in their spawning streams was launched, and Pacific salmon, themselves exotics, were brought in to eat the alewife. You could watch it all happen, and it provided hope that these exotic species were going to be “under control.”
Today, we still have plenty of sea lampreys and alewife, and exotic species entering the Great Lakes arguably faster than when we were less enlightened. There are now 183 invasive species known to already be in the Great Lakes and a new species arrives on average every 28 weeks. Few of today’s newcomers swim in on their own through the St. Lawrence Seaway. Rather, they ride in on the hulls or in the ballast water tanks of ocean going ships. Among the more notorious are the zebra mussel and two small fishes—the round goby and the ruffe (pronounced as two syllables: ruff-ee). But the list also includes things we can hardly see such as the spiny water flea, the fishhook flea, and other zooplankton forms. Fishermen spot them fouling their lines, but most Michigan citizens aren’t aware of them. Instead of scarring fishes or making messes on beaches, the new breed of Great Lakes exotics mess up the food chain and affect the clarity of the water.
Problems associated with ruffe and gobies are not as dramatically apparent as with sea lampreys or alewife, but they are also detrimental. Ruffe and goby populations can grow rapidly, often resulting in less food and habitat for native species. Young ruffe eat the same food and compete for the same habitat as native yellow perch, walleye and a variety of other species. Because of this, ruffe can have a serious impact on perch and walleye fisheries without leaving external scars as a calling card. Gobies eat small fish and eggs and in low light conditions have a major competitive advantage over native fish such as darters and sculpins.
Zebra and quagga mussels, on the other hand, feed by filtering from the water large amounts of microscopic algae, which are an integral part of the Great Lakes’ food chain. They can kill native clams and crayfish by attaching to their bodies, increase aquatic plant growth by increasing water clarity, and compete with larval fish and other aquatic organisms for food. Zebra and quagga mussels have been blamed for so thoroughly clearing the Great Lakes water that plants such as cladophera (an algae) can now grow in much deeper water. When these plants break loose or die they roll up on beaches in piles of unsightly stinking vegetation. Besides environmental impacts, the mussels can clog water intake pipes and foul beaches and boating facilities. The mussels have now been transported to many inland lakes where they are causing further problems.
Some of the exotic zooplankton species are larger than native zooplankton species. In addition, they have long spines that make them hard for young fish to eat. If young fish are unable to consume enough of them, a shift in populations may occur with the exotic species replacing the native populations. This would leave less food for young fish and cause a decrease in native fish populations. They also eat smaller native zooplankton, which could also cause a decrease in available food for native fish.
Today, rather than attempt straight-forward but costly control programs, biologists talk about “integrated pest management,” and acknowledge that for today’s exotic species, the only effective strategy is prevention. Once ruffe, gobies, or the host of zooplankton, mussels, crayfish and other life forms become established you can’t control them. So, the emphasis has shifted to educating the public as to how to keep them out of inland waters, and on legislative action to stop the introduction of new species by requiring the treatment of ballast water in ocean-going ships.
The legal battle took an interesting turn last year when a federal court in California ruled that the Environmental Protection Agency could regulate the ballast water in ships. Michigan had already passed a law regulating ballast water in our state’s part of the Great Lakes. It took effect in January and requires discharge permits before any ballast water tanks are emptied. These legislative and court actions were long overdue, as many conservationists asserted. It is not a case of environment versus economics because regulating ballast water also makes good economic sense. Exotics threaten a $4 billion Great Lakes fishery.
The Michigan Wildlife Conservancy is an active member of the Healing Our Waters coalition, a collection of 90 local, state, Great Lakes Region, and national wildlife and environmental groups. This coalition is working toward a national solution to the discharge of saltwater ballast from foreign ships, the primary source of exotic species in the Great Lakes. This coalition is working toward a national solution to the discharge of saltwater ballast from foreign ships, the primary source of exotic species in the Great Lakes. The coalition advocates legislation that has been introduced in Congress to require treatment of all saltwater ballast entering the Great Lakes/St. Lawrence River system. Until this measure becomes law, the coalition has called for a ban on saltwater ships entering the Great Lakes. A ban may be the best strategy long term because recent research by University of Notre Dame biologists found eight species previously not found in the Great Lakes lining the outside hull of a ship. The ship was dry-docked in Ontario and originated in South America. That means merely treating ballast water might not be the total answer to preventing more exotic species from entering the Great Lakes.
Dr. Patrick Rusz
Director of Wildlife Programs
INVADERS!
Zebra Mussels
Zebra Mussels are native to the Ukraine and Russia. They were introduced into Lake St. Clair and Lake Erie in the mid-1980s and discovered in 1988. A transatlantic freighter coming from Eastern Europe is believed to have introduced them into North America when it dumped its ballast water in the Great Lakes. Since then, zebra mussels have continued to spread throughout all of the Great Lakes as well as the Mississippi, Tennessee, Hudson and Ohio river basins. They most likely will spread farther south and west.
Within 10 years of their discovery in Lake St. Clair, zebra mussels spread through a variety of pathways—including currents, bait buckets and recreational boats—into more than 100 inland lakes throughout the Lower Peninsula of Michigan. Veligers, as the free-swimming microscopic larvae of the zebra mussel are known, can drift downstream or be transported in water that accumulates in the bottoms of boats or in bilge pumps or bait buckets. Adults can attach to boat hulls, engines, aquatic plants or other objects that people move from lake to lake.
Round Goby
The round goby was discovered in the St. Clair River in 1990. It was most likely introduced in the late 1980s via ballast water of transatlantic freighters. The round goby is native to the Ukraine and Russian regions. The round goby is native to the Ukraine and Russian regions. By 1995, the round goby was found in Lake St. Clair, Lake Michigan, Lake Erie, Lake Superior and many tributaries to these lakes. Because of the round goby’s ability to adapt to a variety of water conditions, it has potential to spread throughout Michigan’s inland lakes.
Ruffe
The ruffe was introduced into Lake Superior in the mid-1980s and was discovered in the Duluth/Superior harbor in 1986. It became the most abundant fish in the area within a few years of discovery. This fish is native to Europe and Asia and was most likely transported to the Great Lakes in the ballast water of transatlantic freighters. In Europe, the ruffe is found in waters ranging from deep, cold and clear to shallow, warm and nutrient rich.
Spiny Water Flea (Bythotrephes cederstroemi), Fishhook Flea (Cercopagis penogi) and (Daphnia lumholtzi)
Spiny water flea has been found in all of the Great Lakes since the 1980s. Fishhook flea has been found in Lake Ontario since 1988. Daphnia lumholtzi was found in the Illinois River in 1995 and in Lake Michigan in 1999. It is likely that they were introduced into the Great Lakes through ballast water.