Episode 9: Carpe Carpam

Seize the carp

Have you ever swam at your favorite local spot and encountered a piranha? Believe it or not, this happens across North America all the time - not just in late night B-movies! So how does a fish that is native to South American freshwater rivers find itself living in a Missouri pond? Often these invasive species (a term that describes biodiversity that is introduced into a non-native environment and locale) are simply dropped off by pet-owners that are releasing them into the wild.  In some cases invasive species take hold in a non-native environment purely through accidental circumstances. Occasionally, invasive species are purposefully placed in a locality because someone thought they would serve a specific positive purpose. For example, mosquitofishes (Gambusia affinis) have been frequently introduced in non-native habitats because people wanted them to control mosquito populations. Join us and our special guest, Caleb McMahan, as we discuss this environmentally important topic.

Introducing non-native species frequently has negative effects for the local environment and biodiversity. Invasive species can dramatically alter the fragile ecosystems they are introduced into and severely threaten native wildlife. One example of an introduced fish that has reeked havoc on the native fishes of Illinois is the Round Goby (Neogobius melanostomus). The Round Goby was introduced into the Great Lakes (including Michigan) through freighter vessels traveling from the Black Sea. Once the Round Goby was accidentally brought to the lakes they began spreading at a rapid pace. 

Unfortunately, the increase in these invasive gobies has harmed many native fish populations, such as the Mottled Sculpin (Cottus bairdi). Round Gobies are voracious predators on the eggs and fry of other fishes and they are fiercely territorial with their spawning sites.  This creates competition with native fishes for reproductive space. Another invasive species in Illinois is the Grass Carp from Asia (Ctenopharyngodon idella), which was purposefully introduced in the United States in an effort to control aquatic weeds. The introduction of the grass carps into non-native habitats was carefully controlled, and many of the  introduced populations were gentically modified to be sterile in an effort to curb unwanted population growth in the wild. Despite these precautions, populations of Grass Carp have spread across the United States since their intial introduction in the 1960's.