April 23rd, 2011 | Written by Lisa | 2 Comments
North America’s five Great Lakes – Superior, Huron, Michigan, Ontario, Erie – contain 21% of the world’s fresh water; only the polar ice caps contain more fresh water. So, how can a fish threaten the ecological health of such a massive freshwater system? Asian carp – silver carp and bighead carp – were imported by Southern catfish farmers in the 1970s to remove algae and suspended matter from their ponds. Careless management practices and flooding released Asian carp into Mississippi River basin waterways. They reproduced rapidly and steadily worked their way northward up the Mississippi toward the Great Lakes. Asian carp have no natural predators. They grow quickly to immense size, some measuring more than four feet long and 100 pounds. They reproduce more rapidly than native fish species. Asian carp have rapacious appetites, consuming about 20%-40% of their body weight in plankton daily, endangering the food chain that supports native fish. In short, they out-compete and displace native fish species. Considering that the value of Great Lakes’ commercial and sport fishing industries is estimated at $7 billion annually, Asian carp pose a serious threat to their ecological and economic health. And, silver carp are dangerous to boaters and water sports enthusiasts; known as flying carp, they leap out of the water, damaging boats and injuring people.
The Chicago Sanitary and Ship Canal, opened in 1900, is the major navigational system connecting Lake Michigan to the Mississippi River via the Illinois River. Asian carp thrive in the Illinois River. The U.S. Army Corps of Engineers, in cooperation with other agencies, installed three electric barriers in the Canal to prevent the invasive carp from reaching the Great Lakes. However, DNA monitoring in 2009-2010 tested positive for Asian carp beyond the barrier and in the Calumet Harbor of Lake Michigan. The first physical specimen found above the electric barrier was a mature bighead carp captured in Lake Calumet in June of 2010, just six miles from Lake Michigan. A summit was called to develop a strategy and timetable to construct a physical barrier in the Calumet River between the two lakes. Michigan, joined by Ontario and five other states bordering the Great Lakes, has led the legal battle to permanently separate Lake Michigan from the Chicago Sanitary and Ship Canal, which would restore the natural hydrological barrier between the Great Lakes and the Mississippi River basin. Those opposing closure of the Chicago locks believe such a measure would have a devastating impact on the local Illinois economy.
Another possible point of entry for Asian carp to invade Lake Michigan is a narrow, low-lying strip of land between the Des Plaines River and the Chicago Sanitary and Ship Canal. A 13-mile barrier along this divide has been completed to keep the Asian carp from breaching the strip during heavy rains. Lake Erie is also at risk for Asian carp invasion. The silver and bullhead carp are advancing up the Wabash River system, opening the door for their potential movement into the Maumee River, a tributary to Lake Erie. Although the Wabash and Maumee Rivers are not directly connected, low-lying wetlands between them provide a connection under flooding conditions. To prevent potential invasion, the Indiana Department of Natural Resources installed an Asian carp fence in the Eagle Marsh wetlands with funding from the Great Lakes Restoration Initiative.
The U.S. Supreme Court refused multiple times to intervene in the Asian carp issue, so five states (Michigan, Minnesota, Ohio, Pennsylvania, and Wisconsin) filed a lawsuit in a federal district court of Illinois, requiring the Corps of Engineers to take all necessary steps to stop the migration of Asian carp into the Great Lakes. The U.S. District Judge denied the states’ preliminary injunction in December of 2010, ruling that carp invasion through existing barriers was not imminent. Although legal efforts have not been successful, the White House and Congress have gotten involved in the Asian carp issue. In September of 2010 the White House appointed John Goss as “Asian carp czar” to oversee the $80 million federal attack against Asian carp, which will include better ways to trap, net, and starve the invasive fish, and prevent breeding through environmental DNA. In addition, both the Senate and House of Representatives have proposed legislation giving the Army Corps of Engineers 18 months to devise a plan to sever ties between the Great Lakes and the Mississippi River system to prevent Asian carp invasion. If passed, the legislation will speed up the Army Corps of Engineers’ study, begun last year, but not due for completion until 2015.
Silver and bighead carp are an integral part of Asian culture, where the fish are used as a ceremonial dish. Described as tasting like a cross between scallops and crab meat, demand for carp is high in North American Asian communities, such as Chicago, Toronto and New York. It is illegal to transport live Asian carp across the U.S-Canada border, but some commercial fish companies have tried. Canadian officials have been keeping a close eye on shipments of live fish. Last November Ontario officials seized more than 4,000 pounds of carp in fish tanks crossing the Ambassador Bridge from Detroit into Windsor. And just this month they seized 6,000 more pounds of bighead carp at the border crossing at Point Edward, Ontario. The shipments were bound for Asian communities in the Toronto area. Illegal transportation puts Lake Huron, Lake Erie, and Lake Ontario at direct risk of Asian carp being introduced into their waters.
While carp populations are exploding in the United States, their numbers are declining in some China locations because of over-fishing and habitat destruction. The State of Illinois has entered into an agreement with a fish processing company to harvest 30 million pounds of carp from Illinois rivers, which will be shipped to a Chinese company for resale in international markets where carp is a delicacy. And here in the U.S., a public relations campaign is underway renaming the fish ‘Kentucky tuna’ and ‘silverfin’, served in restaurants and sold in grocery stores. If the trend catches on, perhaps we can angle and eat these invaders to extinction. In the meantime, contact your representatives in government and let them know where you stand.
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