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More foreign invaders threaten Great Lakes



ST. JOSEPH - The monkey goby, tyulka, European perch, Black Sea silverside, and Eurasian minnow could become the latest wave of foreign invaders to threaten the Great Lakes.

Like the round and tubenose goby and Eurasian ruffe, which reached the Great Lakes in the ballast water of ships, they're all native to the Caspian and Black Sea region of Central Asia. And a Notre Dame biology professor belives that unless strict precautions are taken, they could show up in the Great Lakes in the near future.

Dr. David Lodge studied 70 species of fish from the region and concluded the five, based on their tolerance of a wide range of temperatures and salinity, and ability to reproduce and grow quickly, were the most likely to become a nuisance.

"We're making these predictions hoping the outcome won't prove to be true," he said.

The fear is that all five of the fish will compete with native species for food and habitat, shifting the balance of nature. The European perch, for example, is very similar to the yellow perch, and could threaten the popular sport fish.

The tyulka is a shad-like fish that grows to perhaps a couple of pounds, while the monkey goby, Black Sea silverside, and Eurasian minnow are all much smaller, not usually exceeding about six inches.

How soon could they be here? Lodge notes that a researcher predicted in 1981 zebra mussels would spread to North America and by 1986 they were firmly established.

There are literally dozens of examples of problems created by invasive species. Purple loosetrife and Eurasian milfoil are choking out native marsh plants. Before they were controlled, sea lamprey decimated lake trout populations. Zebra mussels have nearly wiped out native clams and clogged the water intakes of hundreds of power plants. It now cost large plants an average of about $1.6 million a year to remove the mussels from pipes and screens and the resulting lost production, Lodge says.

"They're not like other forms of pollution, such as mercury or PCBs," he said. "They're the most irreversible form of pollution we have."

Even now, four species of Asian carp threaten to enter Lake Michigan through the Chicago River. Some can grow to 100 pounds and all are voracious plankton eaters and could damage the food chain. The carp were brought to the U.S. in 1972 by an Arkansas fish farmer and have spread into the Mississippi and Missouri river systems.

While it's too early to tell what the impact of the five new invaders would be, it's not likely to be good, based on the experience with other similar non-native species from Central Asia.

The Eurasian ruffe was first reported in western Lake Superior in 1986 and was found last August in Lake Michigan's Little and Big bays de Noc near Escanaba. Because it spawns up to six times a year and has spines that deter other fish from eating it, there are fears it could drive out desirable species such as perch and walleye.

The round goby was first discovered in the St. Clair River in 1990 and has spread rapidly through the Great Lakes. The tiny fish, which resembles a toad, is sometimes caught off the piers at St. Joseph. It has a competitive advantage over native fish because it can spawn multiple times during a year and tolerate poor quality water. The fear is it will displace native fish by eating their eggs and young.

Ships are now required to dump their ballast before entering the St. Lawrence Seaway but it is inevitable some of that water remains. Lodge says a number of ways are being studied to treat that remaining ballast to eliminate non-native species, including use of ultraviolet radiation, filtration, chlorination, and ozone.

In the meantime, Lodge believes strict controls need to be put on aquaculture and the fish bait trade to avoid accidentally spreading non-native species.

"I hope we're wrong," Lodge stated. "The point is we have to get ahead of the curve, instead of reacting to it."

Boaters, he said, should make sure they clean off their boat before going from one body of another to avoid spreading zebra mussels.

"Really, all you need to do is get off the obvious clumps of plants and mud," Lodge said. "It only takes about two minutes.

"The larval zebra mussels - if they're stuck on the side of the boat - they're going to dry out and die anyhow. We're only worried about the adults."

Like the round and tubenose goby and Eurasian ruffe, which reached the Great Lakes in the ballast water of ships, they're all native to the Caspian and Black Sea region of Central Asia. And a Notre Dame biology professor belives that unless strict precautions are taken, they could show up in the Great Lakes in the near future.

Dr. David Lodge studied 70 species of fish from the region and concluded the five, based on their tolerance of a wide range of temperatures and salinity, and ability to reproduce and grow quickly, were the most likely to become a nuisance.

"We're making these predictions hoping the outcome won't prove to be true," he said.

The fear is that all five of the fish will compete with native species for food and habitat, shifting the balance of nature. The European perch, for example, is very similar to the yellow perch, and could threaten the popular sport fish.

The tyulka is a shad-like fish that grows to perhaps a couple of pounds, while the monkey goby, Black Sea silverside, and Eurasian minnow are all much smaller, not usually exceeding about six inches.

How soon could they be here? Lodge notes that a researcher predicted in 1981 zebra mussels would spread to North America and by 1986 they were firmly established.

There are literally dozens of examples of problems created by invasive species. Purple loosetrife and Eurasian milfoil are choking out native marsh plants. Before they were controlled, sea lamprey decimated lake trout populations. Zebra mussels have nearly wiped out native clams and clogged the water intakes of hundreds of power plants. It now cost large plants an average of about $1.6 million a year to remove the mussels from pipes and screens and the resulting lost production, Lodge says.

"They're not like other forms of pollution, such as mercury or PCBs," he said. "They're the most irreversible form of pollution we have."

Even now, four species of Asian carp threaten to enter Lake Michigan through the Chicago River. Some can grow to 100 pounds and all are voracious plankton eaters and could damage the food chain. The carp were brought to the U.S. in 1972 by an Arkansas fish farmer and have spread into the Mississippi and Missouri river systems.

While it's too early to tell what the impact of the five new invaders would be, it's not likely to be good, based on the experience with other similar non-native species from Central Asia.

The Eurasian ruffe was first reported in western Lake Superior in 1986 and was found last August in Lake Michigan's Little and Big bays de Noc near Escanaba. Because it spawns up to six times a year and has spines that deter other fish from eating it, there are fears it could drive out desirable species such as perch and walleye.

The round goby was first discovered in the St. Clair River in 1990 and has spread rapidly through the Great Lakes. The tiny fish, which resembles a toad, is sometimes caught off the piers at St. Joseph. It has a competitive advantage over native fish because it can spawn multiple times during a year and tolerate poor quality water. The fear is it will displace native fish by eating their eggs and young.

Ships are now required to dump their ballast before entering the St. Lawrence Seaway but it is inevitable some of that water remains. Lodge says a number of ways are being studied to treat that remaining ballast to eliminate non-native species, including use of ultraviolet radiation, filtration, chlorination, and ozone.

In the meantime, Lodge believes strict controls need to be put on aquaculture and the fish bait trade to avoid accidentally spreading non-native species.

"I hope we're wrong," Lodge stated. "The point is we have to get ahead of the curve, instead of reacting to it."

Boaters, he said, should make sure they clean off their boat before going from one body of another to avoid spreading zebra mussels.

"Really, all you need to do is get off the obvious clumps of plants and mud," Lodge said. "It only takes about two minutes.

"The larval zebra mussels - if they're stuck on the side of the boat - they're going to dry out and die anyhow. We're only worried about the adults."
- Sun, 2/23/2003

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