Lamprey, Mussels, and Alewives
Many of the commonly-known Great Lakes fish, including chinook, Coho salmon, and rainbow trout, are actually non-native species that have been introduced to the lakes, either accidentally or intentionally. Over the past two centuries, the introduction of non-native—or invasive—species has fundamentally changed the Great Lakes Basin ecosystem. These changes have greatly affected the economy, health, and well-being of the people that rely on the system for food, water, and recreation.
Until the construction of the St. Lawrence Seaway, which linked the Atlantic Ocean to the Great Lakes with its dams, canals, and locks, the Great Lakes were a landlocked, freshwater ecosystem rich with indigenous species like lake trout, whitefish, perch, and chub. The Seaway ships haul with them something not listed on their manifests: invasive species from ports all over the world, that are “unstitching a delicate ecological web more than 10,000 years in the making” (Egan, Death and Life, xv). Invasive species alongside pollution and overfishing are responsible for the loss of 18 fish species in at least one of the Great Lakes (Great Lakes Fishery Commission). The sea lamprey, alewives, and the dreissenid mussel invasions have dramatically changed the ecosystem and the water quality. The official tally is 186 foreign species in the Great Lakes.
Both fishermen and an equally deliberate environmental accomplice in the form of a sea lamprey decimated the Great Lakes’ whitefish and lake trout populations in the 1930s. Sea lampreys (Petromyzon marinus) are parasitic fish native to the Atlantic Ocean and have remained largely evolutionary unchanged in 340 million years. These creatures attach themselves onto fish and suck out the bodily fluids, similar to leeches feeding on hosts. Sea Lampreys were first recorded in Lake Ontario as early as 1835. The expansion of the Welland Canal, however, brought the sea lamprey into the rest of the Great Lakes. By 1950, the lamprey had reached its peak of invasion, commercial fishing reached a low point, and the lake ecosystem was deteriorating. Vernon Applegate sought to rescue the Great Lakes ecosystem by systematically chemically poisoning sea lampreys where they hatched in riverbeds off the Great Lakes. His efforts have been recognized by the Great Lakes Fishery Commission who named an award after him: The Vernon Applegate Award for Outstanding Contributions to Sea Lamprey Control.
Several concerned citizens wrote letters to Senator Robert P. Griffin concerning the sea lamprey problem, including the Michigan Tourist Council. The Michigan Department of Conservation also contacted Congressman Elford Cederberg about the problem, citing the negative effects sea lamprey had on fishing.
Letter from G. Griffith, Conservation Commissioner to Congressman Cederberg about sea lamprey
The arrival of grey herring only worsened the problems in the Great Lakes. Grey Herring or "Alewives" had migrated and spawned by the thousands into the Great Lakes by the 1960s. Spreading into the Great Lakes via the Welland Canal, the alewives wreaked havoc on lake trout populations, specifically, because alewives eat baby lake trout. In 1967, a bloom of toxic blue-green algae near Gary, Indiana killed millions of the fish. This huge death in alewives across the lakes, leaving a $350 million dollar cleanup in their wake, prompted new investigations into ridding the fragile ecosystem of alewives. Howard Tanner—a colleague of Vernon Applegate at MSU—came to the rescue by introducing coho salmon to feed on the new invasive species. The salmon were off limits to commercial fishermen and were sustained by sport fishing licenses. The salmon have now all but died off and restored the top of the food chain to its natural balance.
The invasion of zebra and quagga mussels in Lake Erie has aggravated the issue. Their presence dramatically changed the water quality and the structure of the lake food web. In the 1980s, the arrival of the dreissenid mussels led to further dramatic reductions in the density of phytoplankton. The density of the mussels peaked between 1998 and 2002, but it has since declined. The rate at which the mussels eat plankton and filter the water around them is destroying the lake ecosystem. The glass-like appearance of the lake waters is a sign of the bottom of the food chain collapsing, since these mussels are prodigious water filterers. Quagga and zebra mussels rapidly spread through many major river systems and the Great Lakes in the 1980s; the latter was discovered in Lake St. Clair in 1988 and the former in 1989 in Lake Erie. Both of these mollusks seem to have been inadvertently introduced into the lakes by unchecked ballast waters of ocean-traversing ships through the St. Lawrence Seaway. The Seaway created a doorway for foreign interlopers, and the ships sailing from foreign waters brought with them microbes and organisms from saltwater territories and dumped them in the freshwater lakes.
Steps have been taken to control the invasive species. EPA standards in the 1980s examined the ballast water in ships. Ballast waters are stored in ship cargo holds to keep the balance of a ship when cargoes are uneven. The ships were “asked” to flush ballast water mid-ocean to prevent contaminations of the Great Lakes. In 1993, the exchange of ballast waters before entering the Seaway was made mandatory. Most recently, ships are now required to use filtration systems like sewage plants to disinfect and flush ballast tanks before entering the Seaway. Here at CMU, researchers like John Scheide have researched ways to mitigate the problem. In 1992, CMLife reported that Professor Scheide would spend a year investigating ways to control the bothersome mollusks, since their invasion was wreaking havoc on powerlines and drinking water facilities. Professor Scheide's research concluded that the mussels themselves were small "clamlike" mollusks that grew to 2-3 centimeters long and that the mussels could be killed by ion imbalances and controlling sodium intake in the lakes.
The Chicago River represents another waterway nuisance for invading species. The Great Lakes Basin and the Mississippi drainage basin are separated by a mountain range. On an expedition down the Mississippi River, Father Marquette and Louis Joilet discovered a sag in the divide; the marshy wetlands less than two miles wide. The strategic location of the portage if it someday breached a canal could open a nonstop corridor between Lake Erie and the Gulf of Mexico. Almost two hundred years later, the construction of the Chicago River finally destroyed the divide. The economic benefits were astounding—to the tune of $6.5 million.
Asian carp were initially introduced into Arkansas riverways to clean up the water. The problem with bighead and silver carp is that they don’t just invade ecosystems, they conquer them. Had Chicago stuck with its continental-divide-busting canal, the carp probably wouldn’t be knocking at the doors. By the late 20th century, the tinkering with the hydrology of the canal had accidentally built a highway for Great Lakes invasive species. The Chicago canal system turned what was a regional problem, with the St. Lawrence Seaway, into a national problem, as the basins of 21 states felt the effects of invasive species. An electrical barrier is now the only block for migrating fish like Asian carp between the Mississippi and the Great Lakes. The U.S. Army Corps of Engineers have now signed an agreement with the state of Illinois to begin work on a $858 million project to prevent this disaster from happening. Michigan has also cosigned the agreement to provide $8 million for the initial work. How does this variety of ecological threats affect human life around the Great Lakes?
