The Great Lakes Commission’s analysis concludes that preventing just one invasive species from entering the Great Lakes watershed could save as much a $5 billion over a 30-year period. Already 10 species have been identified that are poised to enter the watershed from the Mississippi River if they are not divided. Also at stake are the environmental health of the world’s largest fresh water supply and the $7 billion in economic benefits provided by the sport fishing industry on the Great Lakes. The possible impact on tourism dollars hasn’t been calculated. Three possible configurations of barriers were considered in the analysis to prevent the entry of Asian carp and other invasive species, improve wastewater treatment, and still allow commercial and leisure use of the waterways. The three alternatives studied were:
•a down-river single barrier between the confluence of the Chicago Sanitary and Ship Canal and the Cal-Sag Channel and the Lockport Lock
•a mid-system series of four barriers on the Chicago Area Waterways System branches between Lockport and Lake Michigan
•the near-lake alternative of up to five barriers near the lakeshore
A study now being performed by the Army Corps of Engineers is not due to be completed until 2015. Some interested observers say that the administration prefers to wait until the report is finalized before taking decisive action. Meanwhile, the Asian carp are moving north, breeding at a prolific rate and impacting fisheries everywhere they can reach. The Chicago-area waterway is not the only way this unwelcome fish can enter the Great Lakes: some river systems in the Midwest, such as the Wabash and the Maumee, are only separated by wetlands subject to flooding. The Maumee River, emptying into Lake Erie, is feared to be excellent prospective Asian carp spawning grounds if the carp can get to it. In Indiana, crews have finished installing a fence nearly 1,200 feet long and 8 feet high designed to prevent adult carp from using a northeastern Indiana marsh to swim from the Wabash River system into the Maumee River and then on to Lake Erie during floods. Similar to the efforts in Indiana, a 13-mile steel mesh fence splitting the narrow strip of land between the Des Plaines River and the Chicago Sanitary and Ship Canal has been completed to keep the Asian carp from passing between the river and the shipping canal during heavy rains. Other possible entry points are being assessed and projects planned to prevent the spread of these voracious feeders. Asian carp have been caught on Mississippi and Missouri tributaries as far north as Minnesota and South Dakota where the problem is also being assessed.Since the 1970s when three Asian carp species were imported to aid in cleaning Arkansas catfish ponds, the silver carp and bighead carp have proved highly adaptable to our waterways. At the outset, federal government agencies experimented with the imported carp for cleaning sewage treatment ponds and lagoons. Localized flooding quickly moved these fish into adjacent irrigation ditches and river systems where they have steadily expanded their range. These prolific breeders can deposit upwards of 200,000 eggs in a season and grow to over 100 pounds, devouring up to 40% of their body weight daily in the form of plankton. The plankton are thus depleted as a food source for mollusks, insect larvae and the young fry of more desirable fish, reducing the numbers necessary to support traditional fisheries. Asian carp are not good candidates for game fishing as they seldom bite baited hooks. Some intrepid carp fishermen are successful at spearing them or snagging them on treble hooks where that is permitted. Others have built entire bow-fishing businesses along the Illinois River where they take advantage of silver carp’s tendency to jump out of the water when startled. The often-filmed tendency of these fish to jump leads recreational boaters to avoid water where they have begun to proliferate, reducing pleasure boating on some popular tourism lakes and rivers; no one relishes the idea of being hit by a 60-pound flying fish.
The North American effort to halt the northward march of these fish has caught the interest of large numbers of Chinese internet users, where they are endangered and considered a desirable food fish. Schemes to harvest the carp, considered a delicacy by many Asian cultures, have not been very successful as it is now illegal to ship live Asian carp across state lines. Markets catering to Asian clientele are often far removed from the source of the fish, and their patrons prefer live fish for purchase. Areas in the Mississippi delta regions where the carp were previously raised for sale have been stuck with ponds full of the now-unmarketable fish. Some have resorted to selling the dead fish as fertilizer. Efforts at developing a commercial cannery operation have thus far not been very successful due to lack of adequate facilities for processing. Although the mildly-flavored fish is considered a good source of protein, the bony carp are hard to filet and traditionally unpopular in the United States as home-prepared fare. Some deep-south chefs have offered schemes to prepare mechanically-deboned fish for domestic markets as fish sticks and filets but are unable to proceed to profitability of scale due to financing. Some have explored the feasibility of shipping the live fish to Asia, where they are considered a preferred species and are declining due to overfishing and polluted waterways.