How can one keep away unwanted guests? Close the door, or build a wall, right?
That is exactly what the U.S has just done. A 2-mile long earthen 'berm' has been built to keep out invasive species of fishes in America's biggest waterways from entering the Great Lakes.
For the last few decades, environmentalists have been fighting to contain a species of fish known as the Asian carp.
Asian carp are not native to America. But lately, they are growing very quickly and out-competing native species of fish for food and habitat along the inland waterways of the United States.
Unintended Effect!
So how did the Asian carp get here in the first place?
Turns out, these fishes were brought to Arkansas in the 1970s to clean algae from fish farms. By nature, Asian carp are very aggressive and can quickly adapt to new environments. Without a natural predator, these fishes multiplied very fast.
Asian carps are voracious feeders, consuming nearly 50% of their body weight of plankton each day. They soon began to out-compete the native fish for food. In an environment devoid of predators, they grew big often reaching 7 feet in length and about 100 pounds in weight.
Asian carp can be seen often flinging themselves out of the water, striking boaters riding along the Mississippi River. Now they are on the verge of invading the Great Lakes!
Saving The Great Lakes
The American inland waterways are an amazing system where the Mississippi River connects the Great Lakes to the Gulf of Mexico. It is crucial to prevent Asian carp from entering the Great Lakes which is a very important ecosystem and home to many different species of fish.
Wildlife experts had been watching the Illinois river and following the movement of the carp. A few years ago they became concerned about an alternate path to Lake Erie through the Eagle Marsh preservation in Indiana.
The wildlife authorities began looking for solutions and came up with the idea of building a 'berm' - a mud wall constructed of compacted earth with some special rock sections. The fish wall has a height of 7.5 feet. It will replace a chain-link fence that was installed earlier to prevent carp from swimming through Indiana rivers and damaging the diverse ecosystem of the Great Lakes.
The good news is that the invasive fish have not yet reached Eagle Marsh. The berm wall is a preventive step. Besides the berm, other ideas being explored include a "lock and dam" system that will permit water to pass through but keep invasive species from swimming through; and electric fences.
Invasion can be very damaging and could be irreversible. The key to handling this problem is prevention. Hopefully, the berm will serve as the solution to the Asian carp menace.
