Tuesday, April 19, 2011
Asian Carp Invading US Waters
Two species of Asian carp, the silver (Hypophthalmichthys molitrix) and bighead (Hypophthalmichthys nobilis), were introduced to the Mississippi river in the 1970s in order to clean algae out of catfish ponds (Molnár, 2009; EPA, 2010). Due to large flooding in the 1990s, the carp moved into local waterways and have reached far up the Illinois river, threatening the waters of the Great Lakes (EPA, 2010).
This parasitic fish was introduced under the assumption that it would remain only in the habitat humans intended, however in this case nature has prevailed. Molnár explains that parasite have been historically useful in many ways, including selective tasks and for surveying the origin of fishes (Molnár, 2009). The silver and bighead carp, however, have not only broken free of their intended territory, but they are also dominating the food sources over the bigmouth buffalo Ictiobus cyprinellus and gizzard shad Dorosoma cepedianum species. Studies also suggest that the carp is influencing the food supply of other species as well, such as native planktivores and other fish species (Irons, Sass, McClelland, & Stafford, 2007). These species of fish, which weigh over an average of 100 pounds, reproduce rapidly and have a ravenous appetite, are causing lasting effects on the ecosystem (EPA, 2010).
The U.S. Army Corps of Engineers, U.S. EPA, the State of Illinois, the International Joint Commission, the Great Lakes Fishery Commission, and the U.S. Fish and Wildlife Service are working diligently to prevent the carp from reaching the Great Lakes and causing further ecological damage (EPA, 2010). If the carp invade the Great Lakes, they could threaten the $7 billion Great Lakes Fishery, as well as threaten a variety of fish and their subsequent food chain (Borrell, 2010; EPA, 2010).
Tactics to stop the spread of the carp includes electric barriers and poisoning. A poisonous toxin, which claims to only kill fish and freshwater snails, has been dumped as a means to construct electrical barriers. Two electric barriers in the Lake Michigan canal have already been erected, which began in 2002. These barriers shock any fish which attempt to pass. Unfortunately, these attempts may have come too late as scientists have already discovered the DNA of the carp on the shores of the Great Lakes (Stern, 2009).
Borrell, B. (2010, January 6). U.S. Supreme court to act on Asian carp invasion. Retrieved from http://blogs.nature.com/news/thegreatbeyond/2010/01/us_supreme_court_to_act_on_asi.html
EPA. (2010, March 24). Asian carp and the great lakes. Retrieved from http://www.epa.gov/glnpo/invasive/asiancarp/
Irons, K. S., Sass, G. G., McClelland, M. A., & Stafford, J. D. (2007). Reduced condition factor of two native fish species coincident with invasion of non-native Asian carps in the Illinois River, U.S.A. Is this evidence for competition and reduced fitness?. Journal of Fish Biology, 71(D), 258-273. doi:10.1111/j.1095-8649.2007.01670.x
Molnár, K. (2009). Data on the parasite fauna of the European common carp Cyprinus carpio carpio and Asian common carp Cyprinus carpio haematopterus support an Asian ancestry of the species. Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society (AACL Bioflux), 2(4), 391-400. Retrieved from EBSCOhost.
Stern, A. (2009, December 4). Chicago river poisoned to block feared Asian carp. Retrieved from http://www.reuters.com/article/2009/12/04/us-greatlakes-carp-idUSTRE5B25R220091204