Invasive species abound in North America. Some, like the zebra mussel, arrived in the United States unintentionally. Others, like kudzu, the Burmese python, and the common pigeon, were purposefully introduced by people to the continent. Intentionally introduced species often carry a sentimental or economic importance to people. These organisms are escaped pets or farm animals, or decorative garden plants that grow and reproduce rapidly. Invasive species are not new to the Americas. People have brought creatures with them wherever they travel. However, one group of fish has struck a chord with the American public.
Asian carp, as they are called, have been present in the Mississippi River basin since the 1830s but are only now receiving the ample attention they deserve for the threat they pose to the Mississippi River ecosystem. Eight species of cyprinid fish together form the category of Asian carp: the silver carp (Hypophthalmicthys molitrix), the grass carp (Ctenopharyngodon idella), the common carp (Cyprinus carpio), the largescale silver carp (Hypophthalmicthys harmandi), the bighead carp (Hypophthalamicthys nobilis), the black carp (Mylopharyngodon piceus), the common goldfish (Carassius auratus), and the crucian carp (Carassius auratus). Originally raised in aquaculture as food fish, Asian carp (with the exception of the common carp, which has inhabited the Mississippi since the 1830s) escaped from their confinements in Arkansas during the 1970s. Since then, Asian carp populations have expanded upstream 40 to 50 miles annually (Jones 1), threatening the delicate ecosystem of the Great Lakes.
Human attribution of value to the Asian carp led to its domestication and eventual role in aquaculture. Failures in foresight associated with the precautionary principle enabled these species to spread like wildfire across the Mississippi River basin.
Understanding Value: Asian Carp Economics
The Asian carp has immense intrinsic and economic value. But before we discuss these values, we must first explain what a value is. According to Thomas A. More, a value is “a criterion by which a state of affairs (an object or situation) is judged to have or afford the property x, where x is instantiated by a pro or con predicate (e.g. good or bad, beautiful or ugly) as opposed to a predicate that describes matters of fact (e.g.: “green” or “large”)” (More 399). This implies that there is always a valuer, the person who ascribes the attributes to an object or situation.
Brown (also mentioned in More’s article), on the other hand, applies the term ‘value’ to resource management. He first separates preference-based uses of the term from non-preference-based uses, and then gives examples of each. He describes economic value (and other social values) as a preference-based value, but connects things such as intrinsic value to non-preference-related values. He goes on to explain held values as qualities of preference. These held values are different from assigned values in that their importance is derived from a comparison with a relative standard instead of some absolute standard.
More underscores two elements of the definition of value. One: values are criteria used to specify the relationship between one thing and another. Two: values are not facts; they are opinions. Economic value and other assigned values are factual in nature, while non-preference-related values are opinions.
Let’s first examine the intrinsic value of the Asian carp. “The culture of Common Carp has existed in China for at least 3,000 years. During the Tang Dynasty (618-906 AD), people were not allowed to catch, sell, or eat Common Carp because pronunciation of Common Carp and the surname of the emperor were the same. Although culture of Common Carp ceased during that period, culture of other Asian carp species (Grass, Silver, Bighead, and Black carps) began. This practice continued for more than 1,000 years” (Kolar 66). If the Chinese did not associate the carp with an increase in social status, they wouldn’t have attempted to culture the Asian carp in captivity and certainly wouldn’t have relied on it as a staple food fish for thousands of years. The definition of value, after all, implies that some degree of sentimental worth has been attributed to an object, or in this case the carp. There is also a directly proportional relationship between intrinsic value and economic value. With greater intrinsic value comes greater demand for that object. This, in turn, is impetus for an increase in supply to meet a growing demand.
This economic value, or demand, for the Asian carp is tremendous. The bighead carp is the fourth-most-popular fish in aquaculture production. The silver, grass, and common carp surpass the bighead carp in terms of global production. The figure below displays the enormity of the carp’s global economic value.
Aquaculture production of cyprinid species in million tonnes, 1950–2010, as reported by the FAO. Based on data sourced from the FishStat database.
Such value indicates a growing demand for carp on the global market, but also sheds light on the plight of the Mississippi River basin. While only a few bighead carp have been removed from Lake Erie, other carp species have become increasingly common in the Great Lakes region, much to the dismay of Great Lakes fisheries, whose salmon, herring, and whitefish stocks are already plagued by lampreys and other invasive species. The map above shows areas at risk to the carp invasion. A ticking time bomb, the situation only seems to be getting worse as time progresses. Grass carp have been captured in all the Great Lakes except Lake Superior. Common carp abound in the Great Lakes. However, silver carp and black carp remain absent from these waters. Of the Asian carp introduced to North America, only the crucian and black carp lack firmly established populations on the continent. The crucian carp has probably been exterminated, while recent findings suggest that the black carp has established itself in the Mississippi River basin.
Bighead, silver, and grass carp have firmly established themselves in the Mississippi River. The bighead and silver carp are extremely common in these waters, and they have been found from Louisiana to South Dakota, Minnesota, and Ohio. Because of their prevalence, all silver and largescale silver carp were declared invasive species by the Department of the Interior in 2007.
Fighting the Invasive Fish
In order to stem further population expansion among these invasive species, local fishermen have started to extract the fish from American waters. The U.S. Government constructed an electric fence in the canal that connects the Mississippi River to Lake Michigan to block any further upstream expansion by the carp. In 2009, maintenance and subsequent (temporary) shutdown of the electric fence prompted officials to pour fish-targeting toxins into the canal. Millions of fish died, but much to the officials’ dismay, only a few dead carp surfaced. Surely this catastrophe could have been prevented. The entire carp problem could have been avoided if the first American carp aquaculturists followed the precautionary principle and prepared their farms for the inevitable escape of fish.
“Precautionary prevention has often been used in medicine and public health, where the benefit of doubt about a diagnosis is usually given to the patient” (Harremoes 5). In this case, it’s better to be safe than sorry. Or, it was. The silver, bighead, grass, and common carp farms on the Mississippi River could have been better equipped to deal with the environmental consequences of fish farming. Modern aquaculture was in its infancy during the 1970s, and biologists were just beginning to catalog the optimal conditions for carp reproduction. As such, mistakes were made. According to Harremoes, the most important precautionary action that could have taken place is the formation of “a general rule of public policy action to be used in situations of potentially serious or irreversible threats to…the environment, where there is a need to act to reduce potential hazards before there is strong proof of harm, taking into account the likely costs and benefits of action and inaction” (Harremoes 5). An example of precautionary principle in action is the 1985 Clean Air Act. It set in motion a series of precautionary elements that have far-reaching applications outside of clean air alone. First, hazards should be detected early. Research and regular monitoring should be emphasized. Second, the number of environmental burdens should be reduced. Third, ‘clean production’ and technological advances should be promoted. Fourth, the costs of actions to prevent hazards should not outweigh the likely benefits. Fifth, cooperation should be emphasized so common problems can be solved. Finally, action should be taken to reduce risks before full proof of harm is available if the results of inaction are deleterious. All of these aspects of the Clean Air Act should have been applied to the carp fisheries in the Mississippi in the 1970s, when the carp were still restricted to their enclosures. Procedures should have been set in place to handle escaped fish, which have affected their environment in many unforeseen ways.
For example, bighead and silver carp feed by extracting plankton from the water column through their gills. The sheer number of carp in the Mississippi actually chokes the water of its productivity in some places. The nutrients gone, these areas can support little biodiversity. Other filter-feeders, like the American paddlefish (Polyodon spathula), suffer from competitive exclusion for resources and are displaced from parts of their range. The use of lakes to raise carp could have prevented this carp epidemic in the Mississippi because the carp populations would be closed off in the landlocked pond and have nowhere to migrate. This all could have been prevented if precautions like these were implemented in the 1970s. However, precautions are finally being taken to limit the spread of the invasive Asian carp to the Great Lakes, already fragile from pollution, overfishing, and other invasive species.
The Final Word: Lessons from the Invasion
Thus, the carp problem in the Mississippi River is a product of the fish’s social significance and subsequent economic demand in China. Attempts to capitalize on the carp market in the United States eventually went awry, causing an invasive species problem that could have been prevented if proper precautions had been implemented by aquaculturists in the 1970s. This invasive species problem occurs everywhere humans have explored, divided, and conquered. This case study shows how species valuable to humans (economically and sentimentally) can have unintended consequences on foreign environments, from displacing native species to exhausting natural resources in those environments. Once a species has been introduced to an environment, it is almost impossible to eliminate from that environment. The case of the carp in the Mississippi River should be seen an example of when human activities (like aquaculture and conservation) have unintended, irreversible effects on a balanced ecosystem. If anything should be learned from the mistakes made in this situation, never release an organism into a foreign environment. The aftermath could be irreparable.
Fuller, Pam. “Species FactSheet: Cyprinus carpio”. U.S. Geological Survey. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=509. Retrieved 2007-06-19.
Harremoes, Poul, et. al. The Precautionary Principle in the 20th Century: Late Lessons from Early Warnings. London and Sterling, VA:2002
Jones, Meg. “Sport Fish Won’t Sustain If Asian Carp Enter Great Lakes, Scientists Fear”. The Milwaukee Journal Sentinel. 12 July 2002
Kolar et al. 2007. Bigheaded carp: Biological synopsis and environmental risk assessment. American Fisheries Society, Bethesda, MD
More, Thomas A., et. al. “Values and Economics in Environmental Management: A Perspective and Critique”. Journal of Environmental Management (1996) 48, 397-409.18 December 1995.