Category Archive: Invasive Species

Mar 18

Invasion of the Bottom-Dwelling Gobies

Aggressive round goby fish are causing mayhem in the Great Lakes. Hook yourself up with the intel: Thereís trouble in the Great Lakes, and plenty of itís coming from a non-native, bottom-dwelling fish called the round goby. These fish hitched a ride in the ballast waters of ships and arrived in the lakes uninvited. This …

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Mar 06

Grass carp putting down roots

There are extensive efforts underway to keep invasive Asian carp out of the Great Lakes. But one variety has already been popping up there for over 30 years. For decades, people have used sterilized grass carp to control pond vegetation. Over time, some of those fish have escaped to the Great Lakes. Because they could …

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Feb 21

Breakwalls do more than protect harbors from waves

In the Milwaukee Harbor, a 500 foot section of breakwall has been re-designed to support fish. Itís made of huge boulders that fish can hide between. Then itís covered by a layer of smaller rocks that create habitat for prey. John Janssen of the University of Wisconsin, Milwaukee studies life on this breakwall. Heís found …

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Feb 19

A “ruffe” road ahead for the Great Lakes

An aggressive little fish is threatening to disturb ecosystems throughout the Great Lakes. The Eurasian Ruffe is recognizable by its long spiny dorsal fin and frowning mouth. Itís native to Northern Europe and Asia, and made its first appearance in Lake Superior in the 1980s, probably after catching a ride on a freighter from Europe. …

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Jan 27

Lake trout stocking

A fishy tale: In the 1800s, lake trout were abundant in Lake Superior. Then, in the early to mid 1900sÖ Hansen: ďÖ populations began to decline rapidly.Ē Thatís biologist Michael Hansen. He says overfishing and predatory invaders known as sea lampreys were to blame. By the time an effective way to control lampreys was discovered, …

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