Might an ecological natural disaster be averted by closing off a canal? The US Army Corps of Engineers continues to defend the Great Lakes from invasive species of fish. Their battleground is the Chicago Sanitary and Ship Canal.
The Chicago Sanitary and Ship Canal
Inland mariners in the central United States have long used its lakes and rivers for the transport of passengers and goods. The Chicago Sanitary and Ship Canal serves as a northern extension of these waterways.
It was built in 1900 to serves the twin purposes stated in its name. Chicago had been plagued by typhus in the late 1890s, caused by sewage sent down the Chicago River and into Lake Michigan, the source of Chicago's drinking water. The "sanitary" canal brought more water into the Chicago River to dilute the sewage and divert it into the Illinois River, avoiding this Great Lake.
Similarly, as a "ship" canal, it facilitated transportation between the Great Lakes and the Des Plaines River in central Illinois.
This 28 mile long canal connects the Des Plaines River in Lockport with the south branch of the Chicago River. It has a series of locks to allow ships to move with the changes in elevation. The locks also prevent backflow of the water into Chicago.
An earlier transportation project was the Illinois and Michigan Canal. It links the Great Lakes with the Mississippi River system.
Asian Bighead Carp Invaded the Des Plaines River
The Asian Bighead Carp, Hypophthalmichthys nobilis, is a native of Eurasia. These large fish eat plankton, including both protozoa and algae.
Asian Bighead Carp were introduced to the United States in the late 20th century. An Arkansas commercial fishery's intention was to improve water quality in its ponds by eating excess algae. Commercial aquaculture was probably responsible for introductions in other states thereafter.
After escaping from their commercial fisheries, these carp found they could out-eat the native species. Game fish are particularly vulnerable because their young eat plankton, but found themselves competing against large adult carp. Adult bigmouth buffalo fish and gizzard shad, as well as mussels, also lose their lunches to this large invasive carp.
Asian Bighead Carp can reach up to 40Kg (nearly 90 pounds) in weight and 1.4 metres (over 4 feet) in length.
Northern Snakehead Fish Seized the Flank
The Northern Snakehead, Channa argus, is another invasive species originally from China. Although it is most famous for its conquest of the Potomac River on the eastern seaboard, it too is cited as a concern for the Great Lakes via the Chicago Sanitary and Ship Canal.
Several other snakehead species are found elsewhere in Asia and Africa. Northern Snakehead pioneers were probably introduced to the USA by escaping from live-food fish markets or perhaps from aquarists.
It can grow to over three feet (about a metre) in length, and weigh over 15 pounds (over 6Kg). These predators eat amphibians, fish, small aquatic birds and small mammals.
Most surprisingly, a snakehead can survive out of water for extended periods, so long as it stays moist, because it can breathe air. It uses this ability to wriggle from waterway to waterway.
It is a minor danger to anglers, who may be bitten while removing a fishing hook from its jaw. The most menacing aspect, however, is the probable natural disaster to the ecological balance due to its aggressive feeding habits.
Eager citizen conservationists should distinguish the native bowfin for the Northern Snakehead by checking the anal fin. The Northern Snakehead's anal fin is remarkably long, stretching almost half the body's length and ending just short of the tail fin. The bowfin's anal fin is much shorter: its starting point is farther back than midway along the stomach, and ends far short of the tail.
The US Army Corps of Engineers Plans a Blockade
The strategy envisioned by the US Army Corps of Engineers is to seal off the Chicago Sanitary and Ship Canal from Lake Michigan. Closing the locks should effectively blockade the invading Asian Bighead Carp and its likely future partner, the Northern Snakehead. The siege is expected to last indefinitely. After all, these fish have conquered other American waterways and are likely to continue to thrive here. The ecological natural disaster that could result might indeed by averted by acting promptly.
References:
Deborah Braconnier, Phys Org, "Efforts to close canal to Great Lakes", Aug. 8, 2011, referenced Aug. 8, 2011.
USDA National Agriculture Library, "Asian Carp", modified May 11, 2011, referenced Aug. 8, 2011.
USDA National Agriculture Library, "Northern Snakehead", modified Feb. 16, 2011, referenced Aug. 8, 2011.
Leo Nico and Pam Fuller, US Geological Survey, "Hypophthalmichthys nobilis (bighead carp)", revised 11/10/2010, referenced Aug. 8.
North Carolina Wildlife Resources Commission, "Questions and Answers about the Northern Snakehead Fish", Summer 2007, referenced Aug. 8.
Ann Durkin Keating, Encyclopedia of Chicago, "Sanitary and Ship Canal", 2005, referenced Aug. 9, 2011.
Mike DeHaan - Copyright (c) Mike DeHaan, B. Math., of DeHaan Services. Well written and well researched freelance articles; ghost writing for clients.
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