In the 1970s, a fish farmer imported carp from China as a
means to keep sewage lagoons clear of algae. A flood in 1993 allowed many carp
to escape into other waterways. Since
then, it's been feared that if the carp make it into the Great Lakes, it will
ruin the $7 billion sport fishing industry in that area. Electrified barriers
along the Chicago-area waterways are amongst the efforts used to keep the carp
out.
In June 2010, a Bighead Asian carp
was found in Lake Calumet, six miles downstream of Lake Michigan. It was found
in a location in the Chicago Area Waterway System (CAWS) that is above the
electric barrier system. Henry Henderson, a National Resources Defense Council
official, states that "Asian carp are like cockroaches… When you see one, there
are many more that you don't see."
Asian carp can grow to weigh 100 lbs and reach four feet in
length. They can devour up to 20% of their weight in plankton every day, which
can further put a strain on native species. Asian carp can have 3-to-4 sets of
offspring in a year, which can result in one carp having over 2 million eggs.
Alternatives to the current electronic barriers are being
researched, but this can take up to years to come to a conclusive decision. Unfortunately,
the native species of the Great Lakes don't have that long. Many are insisting
that the shipping locks into the Great Lakes be shut down to prevent further
carp invasion.
Other Invasions (in
the U.S.)
Carp aren't the only invasive species in U.S waters. Others
include:
The fight between native and imported species is also taking
place on land.
- In the 1800s, garlic
mustard was introduced to the United States as food and for medicinal use.
This plant competes with native species by crowding them out.
- Yellow star
thistle was also introduced in the 1800s, but by contaminated seed. This
plant is toxic to horses.
- Tree-of-Heaven,
Russian
olive, and princess tree
were introduced as ornamental plants and have been competing with native plants
ever since.
Resources:
National
Geographic – Attack of the Asian Carp
National
Geographic – Flying Carp
National
Invasive Species Information Center
Picture - http://geteconow.com/wp-content/uploads/2009/12/edef234821illinois-river-silver-carp-jumping.jpg
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