Japanese knotweed—a common spring edible and a relative of rhubarb, quinoa and spinach—grows like crazy, so much so that it’s considered an invasive species. Brought here as an ornamental, it’s now better known as a blight; Monsanto even makes a herbicide dedicated to its eradication. On my afternoon jogs, I’ve often wondered what might happen if all my neighbors descended on the rapidly proliferating patches and harvested the tender young shoots for tart, tangy additions to their dinner.
The idea that armies of hungry knife-wielding “invasivores” could eradicate exotic invasive flora and fauna has taken hold in popular culture and among conservation scientists. There are at least two invasive species cookbooks. Fishermen hold tournaments to chase down the Asian carp, which escaped Southern ponds and now threatens to invade the Great Lakes, and biologists have even attempted to re-brand the fish as delicious “Kentucky tuna.”
Eating invasive species might seem like a recipe for success: Humans can devastate a target population. Just take a look at the precipitous decline of the Atlantic cod (PDF). Perhaps Asian carp and lionfish, too, could be sent the way of the passenger pigeon. It’s a simple, compelling solution to a conservation problem. Simply put, “If you can’t beat ‘em, eat ‘em.”
However, as ecologist Martin A. Nuñez cautions in a forthcoming article in Conservation Letters, edible eradication strategies could backfire and might even lead to a greater proliferation of the target species. First off, harvesting plants or animals for food doesn’t always correspond with ecological suppression. (Harvesting knotweed, for example, doesn’t require uprooting the plant, which can easily reproduce even after being picked). While the eat-‘em-to-beat-‘em effort calls attention to unwanted species, in the long run, Nuñez says popularizing an introduced species as food runs the risk of turning invasives into marketable, regional specialties (as with Patagonia’s non-native deer, fish and wild boar).
Before dismissing his cautionary note about incorporating alien flora and fauna into local culture, it’s worth remembering one of America’s cultural icons, a charismatic animal that may help underscore the questionable logic behind the invasivore diet: the Equus caballus, a non-native species originally introduced by Spanish explorers to facilitate transport in the Americas. Now, Nuñez writes, these “wild” horses have become “so deeply rooted in American culture and lore that control of their populations is nearly impossible, and eradication unthinkable.” To say nothing of eating them.
Drawing of Japanese knotweed (Polygonum cuspidatum)/Curtis’s Botanical Magazine, Volume 106, 1880.
Thanks to Roberta Kwok at Conservation magazine, who brought my attention to the study.