WASHINGTON (CN) – Two big Asian Carp dominated a Capitol hearing room Tuesday with their olfactory presence, as an example of the dominance the skittish and powerful fish will exert over the Great Lakes if they breach underwater barriers put up by the federal government. The heavy fish are especially sensitive to noise and are known to leap as high as 10 feet out of the water when irritated by the sound of a motor, damaging boats and injuring people.
The fish — originally from China — threaten to decimate the $7 billion Great Lakes fishing industry as well as water skiers who get hit by the fish, described in the hearing as jumping “bowling balls.”
“We must do everything within our power to prevent the Asian carp from entering the Lakes,” said Minnesota Democrat James Oberstar, chair of the House Subcommittee on Water Resources and Environment
“Waterskiing and other aquatic activities have grown extremely dangerous,” said Great Lakes Fishery Commission Chair Michael Hansen.
One woman nearly died in 2004 after a leaping Asian carp knocked her unconscious while she was jet-skiing, serving as a warning to the owners of nearly 1 million other watercraft operating on the Great Lakes.
During the hearing, a pair of limp Asian carp specimens, their meaty black bodies laying on a gurney, were visible to all in the hearing room. But their presence was most marked by the smell of fresh fish.
“They could become a permanent element of the Great Lakes if they enter the system,” Hansen from the Fisheries Commission said, noting that Asian carp reproduce in large numbers.
Officials announced Monday that Chicago area waterways used heavily by commercial fishing boats will be closed more often in a $78.5 million effort to prevent the invasive Asian carp from entering the Great Lakes.
Bighead and silver carp- collectively known as Asian carp – have dominated some regions, including the waters of a national wildlife refuge near St. Louis, where the fish composed 97 percent of the total weight of the area’s living organisms. “In that area, the fish community consisted of almost nothing but Asian carp,” Hansen said.
Fishers in the Illinois River are now catching more than 25,000 pounds of Asian carp per day, but the fish have a very little commercial value, much less than the value of the fish they are replacing.
The invasive fish were introduced from China to the southern United States in the early 1970s to control algal growth in commercial catfish ponds.
During flooding, some Asian carp escaped and have since moved north along the Mississippi River. They are now at the entrance to the Great Lakes, blocked only by two electric barriers along Chicago shipping canals, which emit electric pulses uncomfortable for fish to swim through.
The fish, which can reach four feet in length and hit 100 pounds, have out-competed local fish. Lacking a stomach, the large fish continually feed, depleting resources, and they can live in a wide range of temperatures, allowing them to spread.
Their diet at the low end of the food chain – mainly microscopic plants and animals – also means the fish compete with the young of many local native species.
A third electric barrier, funded by the Recovery Act, is under construction and is expected to be operational in the fall. More than 34,000 feet of concrete barricades and 33,000 feet of chain-link fence are also being built in flood-prone areas to prevent Asian carp from getting around the barriers during a flood.
Cameron Davis, a senior advisor in the Environmental Protection Agency, said in his testimony that a larger variety of defenses should be used against the fish. “We cannot fight biology with engineering alone,” he said, promoting chemical and biological solutions.
The government is seeking to control ballast water, which is carried in the hull to stabilize ships during transport.
Major General John Peabody of the U.S. Army Corps of Engineers said the current barriers are effective at repelling the fish, but noted that a new test for Asian carp DNA used to determine where the fish population spread, has already found Asian carp DNA upstream of the barriers.
The finding resulted in an intensive fishing expedition that netted more than 1,000 fish, none of them Asian carp, and the government is considering more fishing expeditions and the application of rotenone, a poison that interferes with fish metabolism.
The Great Lakes frequently fall victim to invasive species, with one introduced every nine to 12 months. Ships from the ocean have been responsible for a third of the Great Lakes invaders, Hansen said.
Zebra mussels from Eurasia are just one famous example, having entered the lakes by ballast water in the mid-1980s. They have since spread throughout much of the United States at tremendous financial cost, growing into and clogging water pipes.