By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM
Invasive Asian Carp
An aggressive invasive species—the Asian carp—is threatening the Great Lakes. Able to consume one-third of its body weight in a day, the carp can grow up to five feet (152 cm) long. It also reproduces very quickly. Its presence may spell disaster for the Great Lakes’ $7 billion recreational fishing and tourism industry.
The term “invasive species” is used to describe exotic plants and animals that are non-native to an area. Invasive species can radically affect the ecology of the habitats they invade by out-competing native species.
Recent discoveries of huge Asian Carp in Flatfoot Lake only 10 miles (16 km.) from Lake Michigan are ominous signs that they may have already arrived in the Great Lakes. According to a report on Chicago Public Media WBEZ91.5 (Sept. 19, 2013), at a recent conference in Milwaukee, “… the top federal official in charge of keeping the Asian carp out of the Great Lakes said an 82 pound, 53-inch Asian carp was caught in Flatfoot Lake in August.”
Before the advent of ocean travel, invasive species were hardly a problem for the world. Once global trade began, however, transportation of flora and fauna between continents became commonplace. The problem with imported plants and animals occurs when those species are able to reproduce quickly, overwhelming native species.
The term “Asian carp” actually includes four different species of fish that originated in China but are now found in the United States—the silver, bighead, grass and black carp. The bighead and silver are the two currently encroaching on the Great Lakes ecosystem and more specifically Lake Michigan. Grass and black carp are found further south in the Mississippi River, according to The Christian Science Monitor (Mar. 8, 2010).
According to the U.S. Fish and Wildlife Service, the grass carp was introduced into the United States in 1963. Bighead, silver and black carp were imported in the 1970s. Catfish farms and government fish hatcheries in Arkansas and Mississippi initially introduced the carp to eat algae. When river flooding occurred, the carp escaped. Over decades, they migrated into the Mississippi River system and upstream into the Illinois River system, which connects by canal to Lake Michigan.
Once Asian carp invade a water system, it is very difficult to stop their reproduction. A female bighead carp can carry up to 1 million eggs in a lifetime. Furthermore, because the Asian carp’s digestion is rapid and efficient, they grow faster and larger than most other species of freshwater fish. The bighead, for example, can grow to 60 inches (152 cm) long and weigh 110 pounds (50 kg).
In the United States, Asian carp have no natural predators. While they consume both plankton and other vegetation, they also feed on eggs of native species. This means that they not only eat their competitors’ food, but they eat their competitors before they mature.
Asian carp also pose a physical danger to boaters. If frightened by boats, the Asian carp can leap out of the water up to 10 feet (3 m) high. When one collides with speeding boaters, the fish can cause black eyes, broken bones, concussions and even death.
The Asian carp issue is very contentious in the Great Lakes area. If Asian carp become established in the Great Lakes and begin breeding, the existing ecosystem of the lakes will be forever altered.
Since January 2010, researchers have found Asian carp DNA in Lake Michigan waters. The White House held a summit in February 2010 and pledged $78.5 million at the time to help prevent the fish from further infiltrating the Great Lakes. The efforts included building electric barriers on the Chicago Sanitary and Ship Canal that connects the Illinois River’s headwaters to Lake Michigan.
Exotic species’ invasions are not new to the United States. When a would-be silk farmer brought Gypsy moths to Massachusetts in 1869, they escaped and the result has been devastating. The moths have stripped the leaves of millions of acres of deciduous forest through the northern Appalachians.
Likewise, in 1890, someone released 100 starlings in New York City. Now the birds number 200 million, crowding out native birds across the country. When the exotic vine kudzu was transplanted from Japan to the United States to prevent erosion in 1876, no one could have imagined the impact it would have. Since then, the fast-growing vine has engulfed over 10 million acres (4 million hectares) in the Southeast.
Once an invasive species takes over a habitat, it is very difficult to mitigate. It is easier to keep an invasive out in the first place, although successes in building and maintaining effective barriers are limited. The U.S. government has tried to block non-native species from entering the country since 1912 when it passed the Plant Quarantine Act.
Globally, invasive species cause damage estimated at $1.5 trillion. That figure is almost 5 percent of the world’s gross domestic product (GDP). Michigan hopes that it can stop the Asian carp from taking over, but if the history of invasive species is any indication, the Great Lakes are doomed.
And that is Geography in the NewsTM.
Sources: GITN 1036 Invasive Asian Carp, April 9, 2011; Guarino, Mark, “Great Lakes under threat from invader,” The Christian Science Monitor, Mar. 8, 2010; and http://www.time.com/time/health/article/0,8599,1962108,00.html
Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.