to connected river systems, and spread via continued flooding events. Aside from this, the population was also introduced via human release. The nature of the black carp's diet has led to its use in the United States in the control of snails in aquaculture. Snails are obligate alternate hosts of trematode pests that can cause substantial losses to aquaculture crops. Some state aquaculture laws require the carp to be bred as triploids, to render them sterile, thus minimizing the potential for the fish to escape and create self-sustaining populations. The use of triploids, though, does require the maintenance and use of fertile diploid brood stock at least at some location for production of the triploids. Many mechanical control methods have been used to control the population of Asian carp, including use of noise, walls of bubbles, netting and even explosions, but these have only succeeded in slowing the spread of carp. The most effective methods, such as chemical poisoning, are successful at killing carp, but also affect other fish in the body of water, further disrupting the ecosystem. Currently, novel control methods are being researched that use carp pheromones to control their behavior. Another widespread effort involves using carp as a food source. Locals in areas where carp have invaded are encouraged to catch and eat them. Efforts to prevent Asian carp from spreading to crucial ecosystems such as the Great Lakes or waterways on the West Coast are ongoing. Local laws prevent human release of these fish in these waterways, and population controls have also contributed to this success. No state allows the intentional release of black carp, sterile or otherwise, but the United States Geological Survey reports that more than 60 confirmed black carp have been caught in the Mississippi River basin. This basin is the second-largest drainage system on the North American continent. The Mississippi River spans 2320 miles, while the entire system covers 1,151,000 sq mi. The presence of black carp within this enormous river system means that this highly invasive species has access to a vast range of bodies of water covering the majority of the Midwestern United States. Rivers where black carp have been captured also include the White in Arkansas, the Atchafalaya and Red in Louisiana, and the Kaskaskia and Illinois Rivers in Illinois. One confirmed escape of black carp from aquaculture has occurred on the Osage River in Missouri, but other escapes