-
Chapter Seven ICE AGE RELIC IN OUR TIME
- Minnesota Historical Society Press
- Chapter
- Additional Information
147 Chapter Seven ICE AGE RELIC IN OUR TIME Lake scientists estimate that it takes about four hundred years for a drop of water entering the western end of Lake Superior to reach the St. Marys River at its eastern end. Thus, some of the waters passing through the Soo locks today, though depleted by evaporation and supplemented by rain and snowfall, began their passage across the lake about the time that the English were settling Jamestown and Plymouth. The journey of one such droplet—slipping into the lake out of the St. Louis River and drifting slowly on a gentle current and west wind— would have been a very lonely one for the first century or so. Its first contact with something solid might have been a birch canoe, paddled by a pair of Ojibwe and loaded with wild rice from the sloughs around Chequamegon Bay. Perhaps fifty years later it was part of a giant wave that drove a fur-laden schooner onto the Keweenaw’s rocky shore. Another century passed, and it was whipped into a froth of air bubbles by the screw propeller of an ore boat off Au Sable Point. Then, after another half century that could be only yesterday, the droplet encountered its first pollution as it drifted into Whitefish Bay—a drop of oil and a collection of coliform bacteria from a freighter inbound from Europe with a rusty engine and no onboard sanitary facility. Here was the first indication of the perils to come on its journey through the lower lakes—encounteringsilt,industrialchemicals,agriculturalpesticides, andhuman 148 Shining Big Sea Water wastes—before, after several hundred years more, flowing down the St. Lawrence River into the chill waters of the North Atlantic. Lake Superior today is actually cleaner and clearer than it was at the end of the Ice Age, when it was so clouded by glacial drift that it could not even sustain fish. It is far less polluted than the lower lakes because its cool climate and infertile environs discourage commercial agriculture and because its lake ports have not grown into densely populated metropolises. Politicians and scientists, moreover, have profited by troubles in the lower lakes, and they are better prepared to combat pollution in the largest of the world’s freshwater lakes. To be sure, Lake Superior has had its share of problems in the past hundred years—some that have confounded both scientists and politicians—but, with vigilant guard against alien invaders and regulations to prevent human pollution, there is reason to be optimistic about its future. The Sea Lamprey Invasion The sea lamprey is abiding testimony that nature’s architect, if such there be, is neither benevolent nor aesthetically tasteful. A saltwater alien, the eel-like lamprey, which can reach a length of two feet, has oxygen-intake gills that are mere holes in the side of its head and a round sucking disc for a mouth. Inside the mouth is a toothlike appendage that the animal uses to cut a hole in its prey in order to suck out blood and body fluids. Its favorite victim is a lake trout of about its own size, and when the lamprey has finished its fiendish work, the fish has only about a 20 percent chance of surviving. A lamprey can kill up to twenty pounds of fish during the twelve to twenty months of its adult life. Although the lamprey originated in a saltwater sea, it can adapt to a freshwater lake. Even saltwater lampreys, like salmon, have to spawn in freshwater streams. Nearing the end of their adult lives, male and female lampreys ascend a stream and use their toothlike appendages to build a nest of small stones and gravel. The female deposits up to sixty thousand eggs in the nest, and then both male and female die. The barely visible larvae live on algae in the stream for five or six years and then metamorphose into free-swimming juveniles with a sucking disc for a [3.237.31.131] Project MUSE (2024-03-29 09:59 GMT) mouth. About eight to ten inches in length, they swim into the lake to begin their predatory existence. Although some scientists think lampreys have been in Lake Ontario ever since the St. Lawrence River was freed of glacial ice some two or three thousand years ago, the first positive identification of a lamprey in the lake occurred in 1835. Since this date was shortly after the New York State barge...