The Great Lakes with a Terrific Array of Fish, About 153 Species of Fish
The advance and retreat of glaciers over countless years scraped and scoured the Great Lakes basins until they attained their present form about 10,000 years ago. Creating the greatest system of inland lakes in the world, the Great Lakes have a surface area of 94,200 square kilometres (244,000 km2) and a volume of over 28 trillion yards3 (22,000 km3) of water, 20 percent of the planet’s surface freshwater.
With over 31,660 square miles (82,000 km2) of water, has the highest surface area of freshwater in the world. Lake Huron, the world’s fifth largest lake, is at the same altitude and about the same size as Lake Michigan, the world’s sixth largest lake. Both are joined by the narrow, deep Straits of Mackinac.
Their gathered waters empty into the St. Clair River which flows into Lake St. Clair, which has an area of approximately 460 square miles (1,190 km2). The water continues its stream to the Detroit River before entering Lake Erie, the eleventh largest lake on earth. It’s the earliest, shallowest, busiest, and most eutrophic (lacking oxygen) of the Great Lakes.
The waterway continues into the Niagara River, then into the famous Niagara Falls, where the water descends a total of 325 feet (99 m) before it empties into the last Great Lake, Ontario. The fourteenth largest lake on Earth, Lake Ontario is the smallest in surface area but the 2nd deepest of the Great Lakes. It discharges into the St. Lawrence River, which flows into the Atlantic Ocean in the Gulf of St. Lawrence.
Approximately 153 Fish Species Before Disruption
The first European explorers found a terrific range of native fish. Approximately 153 species were eventually identified before human interference disrupted the ecosystem, first by overfishing, and by lumbering and industrial growth.
As many species of fish have disappeared, about twenty new species are introduced. Some, like the Pacific salmonids, carp, and smelt, were introduced intentionally. Others, like the sea lamprey, alewife, and zebra mussel, gained access to the Erie and Page 786 Welland Canals or by launch together with the ballast water of vessels transporting other freight.
Nowadays, lake trout, burbot, and whitefish are the key catches of a formerly extraordinarily productive fisheries enterprise. Regardless of the decrease in the quality and quantities of fish that is suitable, commercial and sports fishing are still vital excellent Lakes industries. The sports fishery is made up chiefly of Coho, chinook salmon, steelhead trout, walleye, and perch. They draw about five million anglers annually with a regional economic benefit of about $2 billion.
Besides directly water-related activities, presently, one-fifth of this business and trade of the United States is found in the Great Lakes catchment basin due to the availability of abundant clean and cheap fresh water and accessible, efficient water transport among the lakes and into the oceans. For that reason, pollution has taken some obvious as well as more subtle forms.
Employing the lakes as an affordable sewage disposal site for shore city inhabitants began in the early seventeenth and eighteenth centuries and lasted until the beginning of the 1970s. To enhance the quality of the Great Lakes, the initial efforts concentrated on removing or preventing conventional pollutants such as phosphates, suspended solids, and nitrogen.
Deadlier toxic contaminants often aren’t visible and so initially attracted less attention. Over the last fifty years municipal and industrial wastes so polluted the waters, particularly the lower Great Lakes, that, commencing in the middle 1960s organochlorides were identified as dangerous contaminants.
Fish were collecting, through bioaccumulation, relatively large concentrations of agricultural pesticides like DDT (scientifically called dichlorodiphenyltrichloroethane) and dieldrin in addition to the industrial chemical polychlorinated biphenyl (PCB) in their cells.
These were passed to the human food chain/web. By 1980 over 400 organic and heavy metals contaminants were found in fish, and fisherpersons were cautioned to limit their consumption.
The effects of pollutants are observed primarily at the tops of food chains and are often discovered by changes in population levels of predator species. Organochlorines and methylated mercury, by way of instance, bioaccumulate to levels that might result in reproductive failures in fish-eating creatures and birds such as cormorants, eagles, and mink.
Between 1969 and 1972 legislation has been enacted in some states bordering the Great Lakes basin to limit or prohibit the use of dieldrin, DDT, PCBs, mercury and other toxic compounds. After point source discharges were controlled, lake trout and chub, especially in Lake Michigan, showed dramatic declines in those contaminants.
By 1978–79, but the fish contaminant declines were just minor; or the levels stayed relatively steady, reflecting airborne inputs in addition to the remobilization of contaminants from the sediment.
This issue is very likely to continue since the turnover rates of the Great Lakes are prolonged; and mercury, PCBs and the pesticides DDT, dieldrin and chlordane are extremely resistant to degradation in the environment.
Additionally, these chemicals continue to enter the Great Lakes ecosystem from highly diffuse nonpoint sources like airborne deposition, agricultural and urban runoff, remobilization in the sediments, leaching from municipal and industrial landfills, industry and municipal discharges, and illegal dumping.
Though there has been progressing in recent decades, pollution and development practices in the Great Lake area continue to diminish or threaten wetland areas, and numerous invasive species threaten natural biodiversity.
Toxic wastes from discarded computers and other electronic equipment (e-waste) are also an increasing concern. Beginning in 2010, the Great Lakes Restoration Initiative (GLRI), a program meant to remediate pollution and other environmental hazards will permit the U.S. Environmental Protection Agency (EPA) to oversee and encourage numerous national, state, and local recovery efforts.
General GLRI goals include controlling industrial and agricultural runoff, and specific goals include the elimination of millions of pounds of family, medical, and e-waste. EPA officials may also support programs intent on controlling or removing invasive species such as zebra mussels and Asian carp.
Additionally, in September 2010, the GLRI awarded $10 million to biological researchers at Central Michigan University (Mount Pleasant) to evaluate and monitor the health of wetlands residing within the Great Lakes watershed.
Additionally, Cuyahoga County, which includes Cleveland, Ohio, will get $1 million to enhance surface waters in Lake Erie. GLRI funds also have been allocated to decrease sediment deposits in Toledo Harbour and also to do a reforestation project near Maumee, a suburb of Toledo, Ohio.