Recent questions about Asian carp from anglers and non-anglers have prompted this column in an attempt to inform readers about their history, biology, known and potential problems should they colonize the Great Lakes.
They get big; they would be bad for the ecosystem and they paint an ugly picture for the future of our priceless Great Lakes.
"If Asian carp get into the Great Lakes, it will forever change them," is a statement made and supported by most scientists. The following should likewise lead you, hopefully, to that same conclusion.
Factually, there are seven carp species native to Asia that have been introduced into United States waters: bighead carp, black carp, grass carp, silver carp, common carp, goldfish, and crucian carp. This article will focus on the bighead and silver carp, the two species knocking on the door of the Great Lakes. Bighead and silver were first imported to the southeastern U.S. in the 70s, with the approval of the federal government, to clean up ponds on catfish farms. They escaped these farms in the mid-90's during major flood events and got into the Mississippi River system. The bottom line is they have done well in the Mississippi drainage and have spread into many Wisconsin waters, the Missouri River into North Dakota and the Platte River into Nebraska.
In their native Far East habitat, mainly China, they are found at latitude 45 degrees and south, but are able to tolerate extremes in water temperature from tropical to temperate. Bighead carp attain a maximum size of 60 inches and 110 pounds, while silver carp get to 39 inches and 60 pounds. They can live over 25 years. Both species are filter feeders, straining out tiny plants and animals (plankton) out of the water, consuming up to 40 percent of their body weight in one day. They spawn in large rivers and have tremendous reproductive capability, with silver and bighead averaging 269,000 and 777,000 eggs per female, respectively. The best water temperature is 70 degrees Fahrenheit. The fertilized eggs float in the water, hatch in one day, and begin eating plankton in a week.
Silver carp have an unusual habit of jumping out of the water 8 to 10 feet when frightened by the sound of a motorboat or personal watercraft. There have been many recorded injuries to water skiers, tubers and jet skiers. Annually, there is a Redneck Fishing Tournament on the Illinois River in Bath, Ill., where contestants run up and down the river scaring the carp to net, grab, etc., with the most pounds winning.
While everyone talks about the Chicago Ship Canal, there are four other connections to the Great Lakes. They are collectively known as the Chicago and Calumet waterways. Specifically they are:, from west to east: Little Calumet River, O'Brien Lock & Dam, Calumet River, Chicago Ship Canal and Wilmette Pumping Station. A must-read reference: Preliminary Feasibility of Ecological Separation of the Mississippi River and the Great Lakes to Prevent Transfer of Aquatic Invasive Species, on the Great Lakes Fishery Commission's web site, glfc.org/carp/waterwatseparation.pdf.
The only sure method of preventing Asian carp from colonizing the Great Lakes is 100 percent physical (ecological) separation, in other words, undoing what man has done and fill in the five artificial waterways. There are alternatives to the shipping issue, but none should Asian carp become established. The cargo will be shipped, albeit another way.
The economic impact, as estimated by John Lodge of Wayne State University, is $7 million to the shipping industry and $7 billion (yes, with a "b") to the fishing industry, with the latter loss being permanent and the former temporary.
Once Asian carp infest the Great Lakes, they will change the ecology, especially in areas like Green Bay, Bays de Noc, Saginaw Bay, Lake St. Clair, Lake Erie and the Lake Michigan drowned river mouth lakes (Muskegon, White, Pere Marquette, Manistee, Portage, Betsie, etc.) These are very favorable environments for Asian carp. In the Illinois and Mississippi rivers, Asian carp are now 95 percent of the fish population, having replaced native fish species. Declines or extinctions of native fishes will occur, with the aforementioned rivers being living proof. Asian carp are the second biggest contributors to species extinctions in the world.
Lakes Michigan, Huron and Ontario will also be affected, but to a lesser degree, their environments being less productive. None the less, salmon fishing will be impacted, especially on Lake Michigan, where it is a $2 billion a year industry, as alewife populations will decline. Tourism is Michigan's second-leading industry, with sport fishing being a large portion.
Lake Superior would be the least affected, as plankton populations are less. However, the Portage Waterway native fish populations would be impacted, as it is a richer environment and the Sturgeon River provides a spawning area.
The Mississippi River drainage could be the recipient of many of the 184 exotics in Lake Michigan, several of which have already colonized downstream areas. One potential issue is VHS (viral hemorrhagic septicemia), which was spread into the Great Lakes via ballast water, could be move into the Mississippi drainage. Once there, it could infiltrate the very catfish farms which brought us Asian carp and cause massive die-offs, as catfish are a susceptible species.
Recently, three local Michigan Tech students submitted an Environmental Issue Report on Asian carp, in which they suggest starting a "Give-A-Carp" campaign. Great idea and if you agree let the DMG know, so we can pass along contact information to the three innovative young ladies.