Invasive Species: Carp – an Expensive Ecological Problem
As human populations grow, the increasing demand for resources can impact the environment in many ways. Often the damage that is caused by one issue can be compounded by several other factors that are related to other human activities. I am presenting a topic that is important to me and an outdoorsman, conservationist, and concerned citizen. As you may have heard, the Mississippi River basin and the Great Lakes chain is in jeopardy due to the introduction of Asian Carp. I will be educating you about how the issue began, it’s compounding factors and several views on how the matter can be resolved.
Several Carp species were introduced in North America as a source of food and as a means of wastewater treatment. (Asian Carp Regional Coordinating Committee, 2019)
One variant, Crusian Carp was brought to America in 1831 as a food source (Wikipedia, 2020) Crusian Carp originate from England and are now widespread throughout most waterways in North America. Silver Carp, Grass Carp, Black Carp, and Bighead carp were imported from Asia in the 1970s. (Wikipedia, 2020) (Asian Carp Regional Coordinating Committee, 2018) Many of the Asian carp are filter feeders and were brought to America on several occasions to clean wastewater and commercial ponds. (Asian carp introduction, 2020) Many of these carp escaped their ponds during floods and became well established in the Missouri, Mississippi, and Ohio river basins.
Carp are well suited to survive in North America and can cause drastic changes to ecosystems by out-competing native wildlife. As Carp are well known to eat aquatic vegetation so quickly, officials in the state of Florida has purposefully introduced sterile carp to control invasive hydrilla plants. (Staletovich, 2014) The damage caused to native aquatic vegetation is affecting the behavior and wellbeing of native wildlife. Carp also compete for live food and are known to also eat, insects, fish eggs, crustaceans, and mollusks. (Chesapeake Bay Program, 2020) Some Carp are known to thrive in poor water conditions with limited oxygen supply and higher salt content. ( Society for Experimental Biology, 2006) Other effects of human population pressure such as agricultural runoff, salinization, and changes to water flow rates: have resulted in further setbacks for native fish. As carp are capable of withstanding poor water conditions better than the majority of native fish, carp now outnumber native fish in many habitats. “Asian carp establishment would lead to fewer and smaller prized catches such as Lake Trout and Walleye” according to the Royal Ontario Museum. Bighead Carp alone are expected to cause a massive upset to the fisheries of the Mississippi River and the Great lakes.
There are several ways to manage the issue of invasive carp. Since 2004 roughly 607 million dollars has been spent by federal and state governments, on attempts to limit the spread of invasive carp. (FLESHER, 2020) current data suggest the cost will rise to $1.5 billion over the next decade. (Associated Press, 2020) One popular method of removing carp from waterways involves using boats with specialized devices that emit noise and electric current to drive the fish into a series of nets. This method is not as damaging to native species and results in large catches of invasive carp that can be used as fertilizer or as a food source. Using this method, an estimated 6 million pounds of carp were removed from the waters of Kentucky in 2019. The United States Army Corps of Engineers has assisted with the creation of a series of electrified locks and dams that have been utilized in several states to prevent carp from spreading and entering large lakes. Often the flow of waterways if altered to optimize this approach. This method also restricts native species movement to a lesser degree and does not completely stop Asian carp from passing. The Illinois Department of Natural Resources has even attempted dumping thousands of gallons of the toxin Rotenone into a waterway. Rotenone is toxic to fish but is not toxic to the majority of aquatic life, animals, or humans. This resulted in 90 tons of dead fish, primarily native species. (ROSENBERG, 2009) Recently some have suggested the option of reintroducing the currently threatened Alligator Gar fish to slow the spread of Asian carp. Alligator Gar were once widespread in much of North America, Due to their threatening size and appearance, they were nearly hunted to extinction. Alligator Gar will prey heavily on Asian Carp if given the opportunity.
At this point, I am amazed at how widely the Crusian, Silver, Grass, Black, and Bighead Carps have spread. Each species can cause billions of dollars in damage to our economy and irreversible devastation to our ecosystems. This situation is very similar to the recent introduction of Largemouth Bass in Japan’s waterways. I don’t believe the carp invasion can be resolved within our lifetime. I feel a mixed approach is necessary to control and eventually lower non- native carp populations in North America. The methods I favor include, reintroducing the now threatened Alligator Gar, selective netting, and education campaigns. Reintroducing Alligator Gar would help restore balance to ecosystems naturally and would lower Carp populations. Selective netting has provided food and limited agricultural run-off. Due to education campaigns, many avid fishermen are no longer releasing accidental carp catches.
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