Walk into Miya's Sushi Restaurant in New Haven and you can choose to have an extraordinary experience.1 Bun Lai, owner and chef, created the world's first menu of invasive species from which you can order the otherwise undesirable, alien fish and algae found in Connecticut waters—but transformed, by Lai's expertise and ideology, into something tasty that any one of us might eat. More than culinary skill, his food makes a premise about non-native species and suggests a counter to their occupation (Simberloff et al. 2013). Lai's local approach to the global problem of invasive species highlights the interconnections among degraded ecologies, the social transformation of local environments, and processes of globalization.
As an adjective, “invasive” accurately describes a characteristic of some non-native species once placed in novel environments. But the term conceals two important histories: the human intervention that first transports flora and fauna to environments far beyond their place of origin and the complex ecological and social processes by which some species become invader-occupiers (Lockwood et al. 2007:7–15). Exploring those entwined histories reveals the hidden implications of finding invasive species on, of all places, a menu. The example of the Asian carp demonstrates how the natural world intrudes on human infrastructure and landscapes, exceeding the uses to which humans endeavor to put it, occupying and altering the organic and built environment alike.
Speciation, the evolutionary formation of new biological species, occurs primarily through geographic isolation. The river valleys, mountains, oceans, and ice sheets of the world once represented more rigid physical boundaries to the movement of humans and other species (Lowe et al. 2004; Lockwood et al. 2007). But as people dispersed across continents, they moved with plants and animals—some domesticated species and many hidden companions and germs (Crosby 2004). The deliberate introduction of non-native species is as old as the history of human migration but in recent years, their accelerated movement globally made strikingly visible the impact of these non-human occupations of the natural world.
Described as riding “freely on the conveyor belt of global trade,” so-called invaders have become the intimate, and mostly hidden, companions accompanying the goods and commodities regularly transported, imported, and exported for our benefit (Baskin 2003:288). Marine lionfish, zebra mussels, and killer algae are among those detested and feared species that can travel the world over on the hulls or in the ballast water that cargo ships regularly add and dump to maintain balance. Those particular stowaways are known to disrupt the livelihoods of fishermen and farmers who depend on the native species that are destroyed by the eating and habitat practices of invaders—but not all exotic animals and plants caught up in human travel and commerce pose such a threat.
Leading specialists of biotic invasions define invaders as those that “establish a new range in which they proliferate, spread, and persist to the detriment of the environment” (Mack et al. 2000:689). These species are called invading alien predators and described in the language of war as needing to be eliminated, controlled, kept under constant vigilance in order to “stem the tide of invasions,” because of the devastation they can cause to ecological and social landscapes (Baskin 2003:289). Animal invaders eat, compete, and hybridize with native species, sometimes to the point of native species extinction. Plant invaders can disrupt soil stabilization processes making land more susceptible to erosion, they can alter hydrology and fire regime ecosystems, and diminish native populations. Most agricultural pests are non-native; they destroy crops, livestock, and fisheries, raising the cost of food production. Agricultural losses due to introduced weeds are estimated at $24 billion annually with $3 billion in management costs (Simberloff 2013:99). Aggressive invaders can impede navigation, clog waterways, destroy homes, and many human diseases are classified as non-native (Mack et al. 2000; Lockwood et al. 2007; Mooney 2005). Ecological invasions have always been intimately linked to human living, but what is particular to our time is the rate and scope of those occupations.
The magnitude of the threat posed by introduced species was first broadly depicted by animal biologist Charles Elton in his 1958 book, The Ecology of Invasion by Animals and Plants. Like the short series of BBC radio lectures from which the book grew, Elton aimed to inform a broad audience on the movement and implications of non-native species to new environments and the importance of maintaining species diversity (Elton 1958). The topic did not attract much attention until the 1980s when the Scientific Committee on Problems of the Environment (SCOPE) brought together various scientists from around the world to document problems posed by non-native species. The books and articles produced in that decade solidified use of the term “invasive” to describe conservation concerns related to non-native species. Invasion ecology grew into an outwardly recognizable, Googable discipline, but the basic terms related to the field became a problem in semantics (Simberloff 2013:8–9; Lockwood et al. 2007:5–7). The term “invasive” is used interchangeably with “non-native,” “non-indigenous,” “exotic,” and “alien” to denote that a species is not native to a particular environment. But the connotations of such language have opened up the field to criticism and to misunderstandings that come with borrowing from the social relationships among people to understand environmental ones. The appeal of evoking militaristic and pejorative anthropocentric concepts to convey the threat of non-native species can eclipse the material consequences of introduced species invasions.
Invasion is the last step in a series of stages that non-native species progress through when introduced to new environments. They are first transported: if they survive, they establish a population: if they succeed, they spread. Once populations are abundant and unwieldy, suffocating native species and causing ecological and economic harm, the impact renders them invasive (Lockwood et al. 2007:9). Geographer Paul Robbins suggests an alternative to what he describes as the modern model of invasion: “the right plant, in the right place, at the right time” (Robbins 2004:140). Not quite the accident of history suggested therein, Robbins posits that the conditions constitutive of invasive species are cultural and political as much as ecological; he asserts, “it is not species but sociobiological networks that are invasive” (Robbins 2004:140). Non-native species germinate and thrive in disturbed landscapes, places where the biodiversity has already been degraded by human activity.
Human beings create the conditions and geographic patterns of invasion. A recent study makes strikingly visible global flows of potential invasion. Efforts to assess the risk of bioinvasion along shipping routes led researchers from the Universities of Bristol, UK, and Oldenburg, Germany to examine the detailed logs of nearly three million ship voyages that took place during 2007 and 2008 (Seebens et al. 2013:783). Mapped and charted in colourful ways, the results indicate that non-native species are more likely to spread when travelling intermediary distances—too short of a journey results in low invasion risk, too long and the chance of survival and spread is quite slim. Between 8,000 and 10,000 kilometers (about 5,000 to 6,200 miles) to destination ports is the distance most conducive to successful invasive species introductions (Seebens et al. 2013:787). Large ports such as Singapore and Hong Kong, as well as New York and Long Beach are among those at high risk of invasion, but the sheer density of shipping traffic is not the only governing factor—species are sensitive to water temperatures and gravitate toward environmental similarity (Seebens et al. 2013:784–85). Furthermore, researches found that even moderate efforts to treat the ballast water released by ships at ports would yield substantial results in curbing the risk of invasion (Seebens et al. 2013: 787–89). Given the lack of urgency to undertake this preventative measure—despite the drastic increase of invasive species in ports, and the known costs to ecological and social landscapes—we might assume that the disturbances caused by invasives in this context do not affect all human communities equally. In accordance with literature that examines species invasion as a social process, Robbins calls attention to the “power-laden circumstance and divided political and economic conditions into which an invading species arrives” (Robbins 2004:143). The forces of global trade will not yield, here, to the local economies and fisherman that rely on native species in those areas for their livelihoods nor will they concede to environmental preservation.
If the implied terms of invasion ecology are that all of humanity shares in the consequences of environmental degradation, then the explicit claim that the impact of invasion is uneven provides a useful frame of analysis. The current structural approach to invasive species follows what David Harvey characterizes as “‘the standard view’ of environmental management in advanced capitalist societies,” under which “the general approach to environmental problems is to intervene only ‘after the event’” (Harvey 1999:162). Global measures proposed by scientists to prevent the rampant and irreversible spread of invasive species attempt to promote environmental conservation that would broadly benefit human health and economy, but collective action is impeded by the unequally distributed economic hazards of invaders.
Prevention is the most promising approach with the most knowledgeable advocates. One of the world's foremost experts on the topic of introduced species, Daniel Simberloff laments, however, that attempts to predict how introduced species will behave in novel environments are speculative enough that most national and international policy assumes, first, their innocence (Simberloff 2003). It's hard to know when non-natives might adapt harmoniously with native species, or have an always exoticized though accepted presence, or wholly occupy an environment to the exclusion of indigenous species. A guilty, or invasive designation, according to Executive Order 13112 issued by President Clinton in 1999, implies that the introduced species poses a threat to native species, is a threat to human health and safety, and will require enormous financial resources to manage and fight them (Presidential Documents 1999:6183). Last year the Nature Conservancy estimated $1.4 trillion in damages caused by invasives, a total of about 5% of the global economy (Nature Conservancy 2012). The U.S. spends over $120 billion dollars annually to manage invasive species, which collectively pose one of the biggest threats to endangered species—second only to habitat destruction (Simberloff 2013:99).
Pleas by Simberloff and others to change the standard approach of coping with the consequences rather than preventing the problem suggest that a productive approach would be to influence the terms of invasion—to focus on the “sociobiological networks that are invasive” rather than isolate particular species as invasive (Robbins 2004:140). Why bother trying to remove invasive species, given the formidable challenge and immense financial burden? Because, through their occupation, they destroy the very particularities of nature that help us distinguish and appreciate our own, very specific, habitats.
Let me take the case of the Asian carp and propose that it serve as a vehicle for understanding invasive ecology as a social process. Asian carp is the collective term commonly used to refer to four species of fish that are considered invasive in United States waterways: silver, bighead, grass, and black carp. As the popular story goes, U.S. catfish farmers imported these fish species in the 1970s in the hopes that they would eat the algae in catfish pens. This they did, and when major flooding caused these enclosures to overflow, Asian carp entered the Mississippi River in the 1980s and are described as eating their way up American watersheds ever since. After the Mississippi, flooding got them into the Missouri, after that they made their way to the Ohio and Illinois River and currently threaten to enter the Great Lakes. When they reach a new waterway, these voracious eaters dominate and decimate native fish species by outcompeting them for food (Chick and Pegg 2001; Lohmeyer and Garvey 2009; Wanner and Klumb 2009).
The origin story of the flood and the Asian carps' escape may be more mythical than accurate. In a recent presentation, Duane Chapman—Asian carp expert who helped draft national policy on the species' management—revised the story in a way that emphasizes the agency of fishes as moving species. First he described their deliberate U.S. importation as part of a “Silent Spring” ethos that put carp to work eating unwanted vegetation in lieu of chemicals—a preference for using natural rather than chemical algae killers. A well-known trope in invasion ecology involves people and managers, sometimes backed by scientific studies, introducing new species in an effort to modify an environment for human benefit. Many of these stories—of rabbits and cane toads in Australia, European starlings, garlic mustard, and killer bees in North America—end in ecological disaster. Chapman asserts that within a year of their arrival, silver carp were found in the wild, evidence that they escaped enclosed fish pens without the aid of flooding. Chapman described to his audience the carps' unique capacity to jump as high as 10 feet in the air and essentially wreak havoc: they are capable of “emptying boats by slamming boat throttles into high” said Chapman (Budig 2013). The more popular narration of escape and invasion in the 1980s coincides with the scientific SCOPE project's classification of invasive species.
The news article of Chapman's visit to the University of Minnesota went out with the headline “Asian Carp Can Be Controlled, Expert Says” (Budig 2013). Much of the work on invasive species—media overtly so and scientific studies more subtly—treads a delicate balance of conveying the magnitude of the threat of invasive species while trying to maintain a degree of hope that human action is capable of abating the problem or at least affecting some change in the direction of environmental conservation. Reporters and scientists want their respective audiences to grasp the scope, without succumbing to the pessimism of nonhuman occupations. Thus, the belief that human volition can ultimately overpower carp agency becomes a powerful refrain.
The Asian carp is unique in its enormous size and its ability to leap out of water, like a flying fish. Individual carp found in U.S. waterways can easily exceed two feet in length and have been known to grow to over 100 pounds (Burton 2010). Their abundance and size connects to their ability to consume up to 20% of their bodyweight per day in plankton—the small floating organisms that form the foundation of the aquatic food chain and are vital to native fish survival (National Wildlife Federation n.d.). The iconography of these large, prolific invaders captures the absurd, unbelievable and alarming qualities of this invasive species. The ability of carp to captivate audiences and mobilize local as well as federal responses to their occupation makes them ideal icons of invasive ecology. The magnitude of their ability to alter watersheds, to outcompete and destroy native river biota, to disturb human expectations of the natural world, and the financial burden they pose, make them emblematic of the potential dangers of the growing spread of invasive species.
Described as having occupied and invaded our Midwestern Rivers and threatening to destroy fishery and ecosystems in the Great Lakes area, President Obama recently allocated over $50 million to eradicate Asian carp (Flesher 2013). A few years prior, he appointed John Goss as newly created Asian carp director, responsible for preventing these fish from migrating from the rivers of the Midwest into Lake Michigan and then to the rest of the Great Lakes (Alfano 2010). A formidable, and many fear, failing task.
Americans living outside of the Great Lakes and Mississippi River basins might not have registered the news of Obama's decision with the same zeal as microbloggers in China, who within a week of the news, posted more than 85,000 tweets on the subject. Carp is the most popular dinner-table fish in China, and because silver carp are considered a delicacy, populations there are rare due to overfishing. News of a carp invasion in America, and in particular the resources devoted to curtailing it, inspired a range of responses including, “Save that $50 million and toss one million [Chinese] civil servants over to America and let them eat fish for 2 years. Nothing will be left” (Minter 2012). Rather than incriminate the fish, as many Americans have done, this blogger offers a solution that relies on displacing appetites. Something Bun Lai does at Miya's Sushi Restaurant.
The Asian carp scenario establishes setting and culture as key to definitions of invasives. As Robbins emphasizes with another example, the spread of North American lawn turf grasses are not considered invasive even though almost all species are non-native and aggressive (Robbins 2004:144). In an iconic 1998 essay, “Planet of Weeds,” David Quammen described all invasive species, whether they be plants, animals, or other organisms, as sharing a weedy quality with the following characteristics: “they reproduce quickly, disperse widely when given a chance, tolerate a fairly broad range of habitat conditions, take hold in strange places, succeed especially in disturbed ecosystems, and resist eradication once they're established. They are scrappers, generalists, opportunists. They tend to thrive in human-dominated terrain because in crucial ways they resemble Homo sapiens: aggressive, versatile, prolific, and ready to travel” (Quammen 1998:66–67). The previous decade, historian Alfred Crosby saw European colonizing efforts as analogous to the rapid spread of weedy plants in new environments, but unlike Quammen, he gave weeds the benefit of the doubt, opining that “weeds are not good or bad; they are simply the plants that tempt the botanist to use such anthropomorphic terms as aggressive and opportunistic” (Crosby 2004:150). Given the hardiness and fortitude of weeds, Crosby explained that the reason the entire surface of the earth is not covered in them is because “colonizing plants—weeds—can survive nearly anything but success. As they take over disturbed ground, they stabilize the soil, block the baking rays of the sun, and, for all their competitiveness, make it a better place for other plants than it was before. Weeds are the Red Cross of the plant world; they deal with ecological emergencies. When the emergencies are over, they give way to plants that may grow more slowly but grow taller and sturdier” (Crosby 2004:169). Therein lies the silver lining of this particular narrative of occupation. However, it's hard to imagine a time when human-caused ecological degradation will slow down, let alone cease all together, giving some credence to Quammen's more visually and conceptually grim future outlook—the earth would still be covered in green plants, he posits, but they would all be the same plants—all weeds. Quammen takes the final conclusion too far perhaps, after all humans sustain biodiversity, albeit in limited ways, and rather ironically try to create it by introducing species to new environments. But he identifies the important point at which invasive species stop being a conceptual cultural construct: the place where they materially alter environmental landscapes. Humans have to preserve the unique plants and animals on a local level if those species are to survive the encroachment of human development and species invasion.
Introduced species and subsequent invasions exist in tandem with human alterations to the natural world. People lay the framework for invasion and also form important partnerships. Crosby describes the success of particular species and that of Europeans as “a team effort by organisms that had evolved in conflict and cooperation over a long time” (Crosby 2004:143). Robbins expands on this relational dialectic by positing that “the ecological, economic, and political context into which a species invades invariably leads to differential effects on people, animals, and other plants. These uneven effects may create opportunities for ‘alliances’ between invading species and other various human and nonhuman actors that are simultaneously benefited or empowered by the invasion. The rate of invasion may accelerate, therefore, through positive cultural and political feedbacks” (Robbins 2004:146). In the case of Asian carp, his point suggests that we question if human communities benefit from their invasion. The U.S. government 2014 fiscal budget, “proposes to maintain funding for the Great Lakes Restoration Initiative at $300 million” to address environmental issues including “addressing invasive species” (U.S. Office of Management and Budget 2013:153). Whether we characterize the industry of federal managers employed to track and impede the Asian carp invasion as gaining from it, controversy surrounds the human alliances that might perpetuate the invasion—such as creating markets for eating the fish or killing carp as recreational sport. The fear is driven by what David Harvey describes as the process by which social and natural relations become consolidated through “an ecological transformation which requires the reproduction of those relations to sustain it” (Harvey 1996:94). The classification of Asian carp as invasive does not preclude them from integrating successfully into human social environments.
Broader socio-environmental processes determine the conditions and characteristics of invasive species. Recent news of an invasive species generated the following online comment: “Why is it whenever there's some horrible scourge, it's always got ‘African’ or ‘Asian’ in front of it?” (Berman 2013) The name indicates a place of origin for the Asian carp, but it dehistoricizes and obscures that the species of fish it names inhabit very different meanings across time and in different cultures. Critics from fields including history, philosophy, gardening, and landscape architecture have attacked attempts to control invasive species for being influenced by nativism, racism, and xenophobia, for good reason. Appeals against non-native species beginning in the 19th century—inflected with nativist language—became unfortunate metaphors for opposing immigrants and other American inhabitants. At its most extreme, the Nazi's drive to eliminate nonindigenous plants related directly to the campaign to annihilate non-Aryan people (Simberloff 2003:181). In the aftermath of 9/11 the language of eco-terrorism and biological invasions became suspect to critics such as Banu Subramaniam who writes: “we are living in a cultural moment where the anxieties of globalization are feeding nationalisms through xenophobia. The battle against exotic and alien plants is a symptom of a campaign that misplaces and displaces anxieties about economic, social, political, and cultural changes onto outsiders and foreigners” (Subramaniam 2001:34). Subramaniam's concern over the use of xenophobic discourse to draw attention to the threat of invasive species ultimately trivializes nature's agency and eclipses its capacity to occupy environments.
We have always lived in a world where invasive species are a product both of nature and of concept. Seeing them on a menu is particular to our time and not without its critics, including Daniel Simberloff. Consuming the very thing that threatens to destroy community-level biodiversity and with it, some of our most cherished conceptions of what nature means to us trivializes the problem, he argues, and suggests a magic bullet kind of solution for a pervasive problem. The act of eating invasives embed people in the culture of these species and doing so, Simberloff argues, has the potential of devising a problematic niche—creating a market linked to economic incentives might ultimately privilege selling over regulating the product; it might also create incentives for propagating invasive species in more environments (Simberloff et al. 2013). Simberloff prefers complete annihilation, the kind of ruthless approach required to get rid of, rather than live with the problem. I agree with his priorities, but whether we explicitly put invasive species in our bodies, they have always been part of our culture, our companions in evolution, migration, and occupation.