Asian carp pose substantial environmental risk to the Great Lakes if they become established there, according to a bi-national Canadian and United States risk assessment released today. The crazy, jumping Silver carp has been recorded in multiple videos on the Mississippi and other rivers. Silver carp leap high out of the water when disturbed by watercraft. Boaters can and have been injured by these leaping fish. Fear of injury could diminish the desire for recreational boating activities in areas inhabited by these fish. Asian carp proliferate and wipe out native species of plants and fish. A new report draws upon the wealth of Asian carp expertise in US and Canada.
Bighead and silver carps — two species of Asian carp — pose an environmental risk to the Great Lakes within 20 years, with the risk increasing over time. Lakes Michigan, Huron and Erie face the highest risk relative to the other lakes.
The risk assessment report was led by the Department of Fisheries and Oceans Canada and included a team of scientists from Canada and the United States. The report examined the likelihood of the survival and establishment of Asian carp in the lakes. It relied on prevention measures under way through November 2010, and did not take into account extensive preventive actions implemented since that time. The authors also assessed the probable ecological consequences should the fish invade the Great Lakes.
“Ever since these non-native fish first escaped and began to breed prolifically in the rivers of the Midwest, the questions everyone has been asking are: ‘Can a breeding population survive in the Great Lakes and would it be a significant problem if they did?’” said USGS Director Marcia McNutt. “Now we know the answers and unfortunately they are ‘yes and yes.’ This study will help scientists and resource managers in Canada and the U.S. determine how and where to redouble their efforts as they continue to prevent the establishment of these invasive fish.”
The reason for the high risk of invasion is because portions of the Great Lakes offer sufficient food and habitat to enable these invasive fish to spawn, survive and spread, the report’s authors noted. They identified the most likely pathway for Asian carp to enter the Great Lakes is via the Chicago Area Waterway System.
Accidental release followed by ecologic damage
Asian carp were originally imported from Southeast Asia to the southern United States in the 1970s to help aquaculture and wastewater treatment facilities keep retention ponds clean. Flooding of the Mississippi River throughout the 1990’s allowed these fish to escape into the Mississippi River system and migrate into the Missouri and Illinois rivers. The Mississippi, Missouri, and Illinois rivers are all connected and allow fish to swim freely between them. The Illinois River is also connected to the Great Lakes by an artificial, man-made canal system called the Chicago Area Waterway System (CAWS). Bighead Asian carp has been found in Lake Calumet along the Chicago Area Waterway System
The report suggests that the major ecological consequence resulting from the establishment and spread of Asian carp into the Great Lakes would likely be an overall decline in certain native fish species, including some commercially and recreationally important ones. Such declines could occur because Asian carp would compete with prey fish that primarily eat plankton. This could lead to reduced growth rates and declines in abundance of prey fish species, and thus predatory fish would also likely decline. Asian carp also reduce survival of open-water fish larvae — like those of walleye and yellow perch — most likely through competition for plankton or by preying on the larvae.
Is Great Lakes contamination a forgone conclusion?
However, the authors emphasized Asian carp in the Great Lakes and resulting ecosystem damage might still be prevented. And prevention is the best way to avoid the ecologic and economic devastation that is likely to occur if Asian carp enter the Great Lakes.