By Shawn Perich
Once again, Minnesota legislators are debating the best way to battle an invasion of the dreaded Asian carp. The topic this year is whether to close Lock and Dam 1 or install a bubbler system to prevent the carp from migrating further upstream in the Mississippi drainage. Either option is expensive and not necessarily foolproof.
Trying to stop advancing carp in the mighty Mississippi is an ambitious task, but typical of efforts to combat invasive species. In Australia, they once built a fence across the continent to turn back rabbits. The rabbits came to Australia in 1859 when a transplanted Englishman imported two dozen European rabbits from England. Rabbits being rabbits, they multiplied. Soon there were hundreds of millions of rabbits causing massive damage to crops, pastures and the landscape. Begun in 1901, the fencing project, complete with rabbit-proof gates for crossings and bridge, eventually covered 2000 miles.
Even with the fence, Australia’s rabbit problems didn’t go away. Finally, in 1950, scientists introduced a South American virus known to be deadly to European rabbits. The virus decimated the rabbit population, but didn’t wipe them out. Ongoing efforts to control rabbits, including the introduction of a second deadly virus, continue to this day.
I found the story about Australian rabbits in George Laycock’s 1966 book The Alien Animals, The Story of Imported Wildlife. Although the book is nearly 50 years old, it lays out tale after tale about how well-intentioned people have introduced fish, birds and animals to new environment, often with terrible, unforeseen consequences. Without the natural controls found in their native land, these exotic species may overwhelm their new home, as rabbits did in Australia.
Others, over time, become so well-established we may not even think of them as invasive species. House sparrows and starlings, familiar to urban dwellers and farmers alike, were introduced to the United States in the 1800s. Homesick European immigrants and amateur bird enthusiasts wanted to add these familiar birds to the New World. The first man to import starlings did so because the bird was mentioned by Shakespeare. Unfortunately, these noble efforts had ignoble results. Rapidly proliferating, sparrows and starlings damaged crops, became urban pests and outcompeted native birds.
In the past, new species were often introduced to provide game for hunters and anglers. Two such introductions were arguably successful—the ring-necked pheasant and the brown trout. Introduced from China to Oregon in 1882, the pheasant did so well the state held its first hunting season in 1891. Within a few years, pheasant were released in 48 states, although they only became established in 18. Perhaps the pheasant was the right bird for the times, as expanding agricultural production was eliminating habitat for native grassland birds like the prairie chicken. The remaining patchwork of crop land and fallow ground was perfect pheasant habitat.
The success with pheasants inspired bird enthusiasts, sportsman’s clubs and wildlife agencies to try all manner of game birds from Europe, Asia and Africa. Only two species, the gray (Hungarian) partridge and chukar have become established. One Old World bird, a migratory quail called the coturnix, was stocked repeatedly in the United States for at least 80 years. The stockings always failed because the migrant coturnix flew away, yet this did not stop game departments from spending hundreds of thousands of dollars raising and releasing the little birds.
The brown trout originated in Europe but was stocked the world over by travelling trout anglers. In the United States, the brown trout filled a niche in waters that had become either too warm or too heavily fished to support native eastern brook trout. In the West, browns sometimes compete for habitat with native cutthroats and rainbows. While browns are still stocked in waters where they don’t reproduce, mostly they survive as wild populations. Prized by fly-fishers, the brown is largely regarded as a welcome introduction.
Less welcome among anglers is the common carp. Rudolf Hessel, a government fish culturist, brought carp from Europe to Boston in 1877. Immediately afterward, he went to Washington, D.C. where he was applauded by Congress. Within two years, carp for brood stock were shipped to 25 states and territories. In 1883, a total of 260,000 carp were sent to 298 congressional districts, no doubt to meet the enthusiastic demands of constituents. Most of the early carp shipments were destined for farm ponds and similar controlled environments, where budding fish farmers hoped they would profit by producing a valuable food fish.
That hope soon turned to despair. People soon discovered carp weren’t very good to eat. Carp escaped from ponds and were intentionally stocked lakes and streams, quickly becoming established in new waters. They were so prolific they crowded out more desirable native fish. Soon fish scientists across the country were contending with burgeoning carp infestations.
Within 20 years, Americans were ruing the introduction of carp. Already they had begun to devastate the shallow lake habitat preferred by native waterfowl. In Wisconsin, migrating canvasback ducks stopping coming to Lake Koshkonong shortly after carp were introduced in 1880, because the fish destroyed the wild celery that attracted the ducks. In 1901, the United States Commission of Fish and Fisheries began studying ways to control or eliminate carp. More than 100 years and countless studies have passed since then and we are no closer to a solution for carp problems.
But here’s the kicker. In 1966, when Laycock wrote the book, we already knew that stocking critters in new environments was a really bad idea. We were already spending millions of dollars annually to control carp, pigeons, nutria and other exotic pests. We’d seen introduced species wipe out native ecosystems, such as the devastation wrought by sea lamprey on the native fish of the Great Lakes. We knew all of this in 1966—and we had yet to bring Asian carp to the United States.
Like so many previous invasive species, Asian carp were part of a government project to expand fish farming during the 1970s. Many fisheries professionals warned that rearing Asian carp was a mistake, due to the likelihood they’d escape into the wild. That’s what happened. In fact, the fish escaped from a government fish hatchery during a flood. Since then, we’ve fought a losing battle to prevent their spread into new waters.
I’d like to think that closing Lock and Dam 1 will halt the spread of Asian carp into Minnesota’s prime fishing waters. I’d like to think that spending millions to develop a new aquatic invasives research center at the U of M will lead to the development of a magic bullet that will somehow eliminate Asian carp or zebra mussels. I’d like to think that if we throw enough money at the problem and stay firm in our belief that we are fighting the good fight, then sooner or later our problems with invasive species will be over. But every time I see a house sparrow or a carp, I’m reminded that history suggests otherwise. We still aren’t smart enough to end new introductions of exotic species. I don’t know why we think we’re smart enough to get rid of them after we do.