Are Asian Carp Poised to Invade the Great Lakes? Exploring the Question
Over the centuries exotic species including zebra and quagga mussels have invaded the Great Lakes and reconfigured their eco systems. For the past five decades, Asian carp, especially silver carp and bighead carp, have been swimming and spawning their way to their version of exotic species invasion and reconfiguration
Americans didn’t confront Asian carp- black, silver, bighead, and grass- until the 1960s and 1970s when fish farmers in Mississippi, Missouri, and Arkansas exported Asian Carp to America and inadvertently created a serious threat to Great Lakes eco systems and economies.
Canadians didn’t confront Asian carp until the expected carp invasion of the Great Lakes and its Asian immigrant population created a market for them. Asian carp are shipped from the United States to Canada in trucks crossing the Ambassador Bridge in Detroit. A traffic accident could release them into local waterways and sometimes people voluntarily release them.
A United States-Canadian report released in July 2012 stated that if carp become established in one area of the Great Lakes, they could spread of all five Great Lakes within twenty years and decimate native species
The American private fish farmers first imported bighead carp, native to the large rivers of eastern China, to improve water quality and increase fish production in catfish ponds. They were also used in federally funded sewage treatment experiments. During floods, especially the extensive Mississippi River flooding of 1993, the carp escaped from the culture ponds and into the Mississippi River basin. In 1994, several bighead carp escaped from a pond in Missouri into the Osage River and from there they spread to the Kansas and Missouri Rivers. In recent years, Asian carp have been reported and recorded along the borders of at least 18 states that have connecting waterways to the Great Lakes.
Asian Carp have crowded native fish species out of the Wabash, the Calumet, and the Illinois Rivers and make up over 90 percent of the total fish population in some parts of the Mississippi River basin. Bighead and silver carp can move from 10-15 miles a day and they can quickly establish themselves in waterways. The Great Lakes are the next water highways in line for their trip through North America.
According to fish biologists, silver and bighead carp pose the greatest threat to the Great Lakes. If they become established in Lake Erie, they will decimate the walleye, perch, and bass fisheries by eating their food. Even using silver and bighead carp as sports fish instead of native species wouldn’t sustain the sport fishing industry. Anglers fish for line caught fish and carp are small mouthed filter feeders that need to be caught with nets. The loss or diminishing of the 4.5 billion a year Great Lakes fishing industry would be a staggering blow to the economies of Midwestern states and create a ripple effect throughout the country.
Asian Carp Readily Adapt and Upset Ecological Balances
Asian carp, especially bighead and silver carp, have certain biological characteristics that spell trouble for the Great Lakes. Asian carp are voracious eaters, dining mainly on phytoplankton which are the foundation of the food china in the Great Lakes. They eat the food for native fish populations although not the fish themselves and the food chain collapses. They upset the ecological balance in the rivers and lakes that they dominate.
Dr. Chris Jerde, a research associate professor at the University of Notre Dame, points out that black carp are molluscivores- fish that eat mollusks. “Native Great Lakes mussels are barely hanging on thanks to zebra and quagga mussels. The black carp would likely decimate native mussels,” he said.
Since Asian carp are rapid reproducers and have no natural predators, they quickly turn a toe hold in a new ecosystem into a take over. Black, grass, bighead, and silver carp can produce hundreds of thousands, even millions of eggs a year.
The breeding cycle of a silver carp ranges from three to ten years. They live in rivers and streams and feed in schools mainly on phytoplankton, plant based microorganisms that are the basic diet of Great Lakes fish. After they spawn they return to larger bodies of water to resume feeding. A 26 pound silver carp is capable of producing 4.2 million eggs a year.
The U.S. Fish and Wildlife Service reports that silver carp can grow a foot per year, measure 40 inches and weigh 60 pounds. Silver carp leap when frightened or stimulated and they have knocked fishermen from their boats and caused serious injuries when they land in boats.
Big head carp can grow to be five feet long and weigh 110 pounds. They usually eat zooplankton – tiny animal organisms that native species in the Great Lakes, including whitefish rely on for food. Zooplankton tend to eat phytoplankton and when silver carp and big head carp make heavy inroads in the zooplankton and phytoplankton supply, the native fish starve.
Exclusively freshwater fish, bighead carp prefer large rivers and won’t spawn in brackish water or small streams. They spawn after spring rains have flooded rivers and their externally fertilized eggs float downstream. A 39 pound bighead carp can produce 1.1 million eggs a year.
Asian Carp Have Established Beachheads and Are On the Move
Since 2003, black carp, bighead, silver, and grass carp are known to be well established in tributaries of the Mississippi River and in the Mississippi River basin. They have been captured from Louisiana to South Dakota, Minnesota, and Ohio. In the first decades of the twenty-first century, Bighead and silver carp are swimming and spawning closer to Lake Michigan and Lake Erie.
In April of 2010, both Canadian and American media reported that a live bighead Asian carp had been found in the Calumet River, just six miles from Lake Michigan. The Chicago Sanitary and Ship Canal or the Chicago Drainage Canal provides a primary point of passage for bighead and silver carp into Lake Michigan. It is the only connection between the Great Lakes and the Mississippi River system. The Mississippi River system links to the Chicago River or the Calumet-Saganashkee Channel by way of the Illinois and Des Plaines Rivers and the Chicago or Calumet Saganashkee Channel links to Lake Michigan. Completed in 1900, the Chicago Sanitary and Ship Canal also carries Chicago’s treated sewage into the Des Plaines River.
Before the building of the canal, the sewage in the Chicago River flowed into Lake Michigan which supplied drinking water to the city. The flow of the Chicago River was reversed when the canal was built to flow inward from Lake Michigan instead of outward to Lake Michigan. The Sanitary and Ship Canal is part of the Chicago Wastewater System that the Metropolitan Water Reclamation District of Greater Chicago operates.
The United States Army Corps of Engineers considers the Chicago Sanitary and Ship Canal as the first likely point of invasion of the Asian carp. The Corps set up and monitors a series of barriers, including an electric fence, on the Chicago Sanitary and Ship Canal to prevent Asian carp from getting into Lake Michigan. About 25 miles from the lake, the electric fence is the only barrier keeping the carp from Lake Michigan.
.The U.S. Army Corps of Engineers reports that the second most likely point of Asian carp invasion is through the Maumee River, which flows into Lake Erie at Toledo, Ohio. Spawning populations of Asian Carp were found in the Wabash River near Lafayette, Indiana in late May 2010, and a consortium of governmental agencies built a 1,700 foot mesh fence across 700 acre Eagle Marsh in northeast Indiana to keep the carp out. Eagle Marsh is a potential path for Asian carp to move from the Wabash River to the Maumee River basin during flooding and through the Maumee River into Lake Erie.
According to Michael Hansen of the Great Lakes Fishery Commission, the warmer and shallower waters of Lake St. Clair and Western Lake Erie would make ideal spawning grounds for the Asian carp. Lake St. Clair connects to Lake Huron and Lake Huron connects to the St. Mary’s River, Lake Superior and Lake Michigan.
Bighead and Silver Carp Leave Tell Tale DNA
Over the last decade, steadily accumulating paper and DNA trails have documented the Asian carp’s looming presence and movement toward the Great Lakes. A June 19, 2012 story in the Milwaukee Journal and cited in the New York Times reported that the percentage of Army Corps of Engineer water samples testing positive for Asian Carp DNA rose from 1.5 percent in 2011 to nearly 15 percent in 2012.
The samples were taken above the electric barrier in the Chicago Sanitary and Ship Canal. The Corps of Engineers speculate that the positive DNA samples don’t mean that many live carp have crossed the barrier. They say that the molecules of DNA material could be coming from barges with contaminated bilge water, from carp flopping onto barge decks, from the feathers or excrement of birds or from restaurants in the Chicago area that serve Asian carp. None of the DNA testing from 2011 or 2012 has revealed the presence of bighead carp.
Conservationists and scientists at the University of Notre Dame who developed the fish DNA testing method disagree. They say that the numerous positive samples found in a variety of different places in the Chicago canal system indicate that there are at least a few live fish above the barrier. They also argue that the tool used in testing is so sensitive that it can detect the presence of low fish numbers that traditional fish survey tools like nets and electro shocking devices might miss.
Researchers from the University of Notre Dame, Central Michigan University and the Nature Conservancy also reported the presence of DNA from bighead and silver carp after examining more than 400 water samples from Lake Erie taken in August 2011. Although three bighead carp were caught in Lake Erie between 1995 and 2000, this is the first reported instance of DNA from silver carp and bighead.
Ohio waterways are hotspots for bighead and silver carp DNA. Water samples from Sandusky Bay taken less than three miles where the live bigheads were previously caught yielded four positive hits for bighead carp. Two positive hits for silver carp came from water from northern Maumee Bay. In January 2012, scientists with the U.S. Geological survey reported that the Maumee River, flowing into Lake Erie at Toledo, Ohio, is a favorable habitat for Asian carp to spawn.
The positive water samples were part of the approximately 2,000 water samples that Chris Jerde, a Notre Dame biologist, and his colleagues collected from Lake Michigan, Lake Erie, and Lake Superior in 2011 as part of a large scale search for invasive species in the Great Lakes. He said that he and his fellow scientists have been processing the samples, but they didn’t find any Asian carp DNA until July 2012.
Scientists aren’t sure whether carp DNA is evidence of actual fish, and some of them believe that the DNA could be from fish eating birds. Finding the DNA is troubling because scientists say that Lake Erie could suffer the biggest consequences from an Asian carp infestation. Lake Erie is the shallowest and smallest of the Great Lakes by volume, but it has the most abundant fish population because of its warm temperature and plentiful food supply.
Asian Carp and American Politics
Both the United States Congress and the United States Supreme Court have been involved in the struggle over Asia carp and their expected invasion of the Great Lakes. In November 2009, water samples revealed that carp DNA had been found above the electric fish barrier that had been erected in the Chicago Sanitary and Ship Canal which is just a few miles from Lake Michigan.
The Great Lakes States of Michigan, Wisconsin, Minnesota, Ohio, and New York asked the Supreme Court to reopen a 1920s case which said that the Canal specifications could be re-negotiated if it was found to be harmful. The suing states wanted to force the U.S. Army Corps of Engineers to re-engineer the canal system to again separate Lake Michigan from the Mississippi River, a project that could take years and cost millions of dollars.
The suing states also wanted the Supreme Court to issue an emergency injunction to force the Corps of Engineers to temporarily shut down two navigational locks in Chicago to keep the Asian carp out of Lake Michigan, a request that Chicago businessmen strongly opposed. In April of 2010, the United States Supreme Court rejected the state of Michigan’s request for an injunction to force Illinois to stop its waterways from flowing into Lake Michigan. This left the Asian carp issue in the hands of federal and state officials.
In the meantime, the Army Corps of Engineers agreed to conduct a study of the practicalities and costs of disconnecting the Chicago Sanitary and Ship Canal and estimated that it could release the study results in 2012. On Wednesday, June 30, 2010, legislators from Great Lakes states including Michigan, Minnesota, Wisconsin, Ohio, and New York introduced a bill in Congress called “The Permanent Prevention of Asian Carp Act,” that would force the U.S. Army Corps of Engineers to “expedite” a study that outlined the best way to separate the Mississippi River Basin and the Great Lakes.
On Friday, July 13, 2012, both houses of Congress passed the Stop Invasive Species Act requiring the Army Corps of Engineers to report the results of its study of how to rebuild the natural separation between the Lake Michigan and Mississippi River basin that the Chicago and Sanitary Ship Canal destroyed when it opened over 100 years ago. The Corps of Engineers will report the results of its study at the end of 2013 instead of its original completion date of 2015. The bill, sometimes called The Asian Carp Act, is included in a highway funding bill that President Barack Obama has signed.
The Army Corps of Engineers is also studying other options to prevent the 39 other invasive species it has identified as poised to move between the Lake Michigan and the Mississippi River basins if pathways like the Chicago Sanitary and Ship Canal aren’t closed.
Canada Confronts Bighead and Silver Carp
American and Canadian scientists at an April 2010 Great Lakes Fishery Commission meeting in Windsor, Ontario, warned that the Asian carp could dramatically transform all of the Great Lakes. Canadian environmental groups including Ecojustice, Environmental Defence Canada and Great Lakes United have asked the U.S. Environmental Protection Agency to act more quickly and consider Canadian interests in dealing with the Asian carp.
The Canadian department of Fisheries and Oceans has warned in reports that Asian carp present a significant risk to Canadian fresh waters and that they would not only survive but thrive in the Great Lakes and across most Canadian provinces because of comparable water temperatures to their native range in China.
“There is an urgent threat of the carp entering Lake Michigan if the nearby waterways flood into the Chicago Sanitary and Ship Canal,” says Mary Muter Georgian Baykeeper from Georgian Bay Forever. “One heavy rain event could spell disaster for the Great Lakes and inland waters across Canada.”
A Canadian Fisheries and Oceans 2012 Report draws some ominous conclusions. It says that the Chicago Area Waterway System is the mostly likely entry point for Asian Carp into Lake Michigan. The report does not evaluate the effectiveness of the electrical barrier in the Chicago and Sanitary and Ship Canal, but says that the complexity of the Canal system and the proximity of the bighead carp populations indicate that the Canal is the likely entry point.
The Report predicts that once bighead carp have entered the Lake Michigan basin, they will spread to other lakes within twenty years. They will spread rapidly in Lakes Michigan, Huron, and Erie and possibly in Superior. It will take bighead longer to establish themselves in Lake Ontario because of its distance from the other Great Lakes.
Bighead carp will also find suitable food, thermal, and spawning habitats allowing them to survive and thrive in Lake Erie, Lake St. Clair, and attractive bays of Lakes Superior, Michigan, Huron, and Ontario.
Perhaps most sobering is the Report’s statement that as few as ten adult females and a similar number of adult males have a more than 50 percent probability of successfully mating each year within the Great Lakes Basin.
The Canadian Fisheries and Oceans Report concludes its summary with a tinge of perhaps unintended irony when it says, “To reduce the probability of introduction (either at the arrival, survival, establishment or spread stage), and delay or reduce subsequent ecological consequences, immediate prevention activities would be most effective, especially in conjunction with population management activities.”
Somerrill, Barbara, Asian Carp Animal Invaders, Cherry Lake Publishing, 2008