Overfishing. This is one of the major issues faced not just in the great lakes, but all around the world. The seas are been emptied of fishes and other bio diverse organisms due to overfishing. In fact, this factor has contributed a great deal to the recent decrease of the fish population in the great lakes even though many people neglect it(Owen 1).
Native Americans were the first humans to great lakes, but they did not deplete the natural resources. However, the coming of the European settlers in 1870s brought evidence of fish population decrease in the lakes said Gerald Smith, a retired biology professor and curator emeritus of fish, who spoke to an audience of more than fifty students at the University of Michigan Exhibit Museum of Natural History as recorded by the Michigan daily news. Millions of fishes were captured without any regulation or control from the government. This in turn led to a continual decrease in fish population and extinction of some of the fishes species.
Blue pike is one that falls into this category. It’s almost gone extinct from the great lakes today. Found mostly in lake Erie, the blue spike was once an important contributor to the ecosystem. It lived in the clearer portion of the lake and in deep, cold water. According to Pam Belluck’s post in the New York Times, these fishes were significant catches for the commercial fishing industy in the early 20th century. Millions of this fish species which harvested yearly, and it yielded a lot profit to the industry at the time. Continual fishing of this specy and other factors such as pollution, habitat changes and so on has led to the depliction of the blue pike population in lake Erie.
Fishing is a huge success when there are regulations to control the harvest of wide varieties of it especially when the fishes are only available in minute quantities. The blue spike has gone extinct from lake Erie due to lack of overfishing and other factors like pollution according to Paul Schiff’s "Blue Pike: Still Extinct from Lake Erie Waters." Moreover, the recent decrease in the biodiversity of the great lakes has affected the fish industry, and brought threat to the survival of higher aquatic predators, which depend on these smaller fishes for food. The government has since sought to compensate by setting fishing quotas (www.on.ec.gc.ca).
Introduction of invasive species. The introduction of invasive species to the great lakes has contributed to a great extent in the habitat degradation. Ballast water has been a major means of this introduction since the last century. Ballast water is the water carried by cargo ships in order to maintain balance.
According to MIT Sea Grant, it is estimated that as many as 3,000 exotic species are carried in ships' ballast around the globe. In the great lakes these new invasives thrive to survival, consume other fish species and create unsafe habitat for other organisms.Invasives stow away in ballast tanks, and when the ship dumps in the US this water is pumped out along with the invasives to the water body of the great lakes.
More than 70,000,000 tons of ballast water are dumped in U.S. waters annually (www.greatlakeswiki.org).‘Since 95% of all foreign goods by weight enter the U.S. through its ports, the potential for invasive species impacts on coastal communities is immense.’(www.epa.gov) .Some of the already introduced invasives in the great lakes, which contribute to habitat degradation are sea lampreys, quagga mussels, zebra mussels, microscopic plants and other animals.
Sea lampreys are like salmons, ocean fishes that spawn in fresh water. Found in lake Michigan, Huron, Erie, Ontario, and Superior, sea lampreys grow to about twelve to twenty inches in length and about eight to thirteen ounces in weight. They are parasites to other fishes, such as lake trout and they are equipped with tooth filled mouth and a long snake-like body.
Introduced through the welland canal lake Erie in 1921, Sea lamprey gradually colonized all of the other great lakes, Lake Ontario in 1835, Lake Huron in 1932, Lake Michigan in 1936, and Lake Superior in 1946 (www.umesc.usgs.gov). They kill their prey by fastening to them and using their tooth filled mouth to rasp holes and suck through their parasite’s blood and body fluids for their own survival. These species posed a great threat to the survival of fishes in the great lakes until scientist discovered a chemical that selectively killed the sea lamprey’s larvae in their spawning streams. The discovery helped decrease the population of these deadly species in the great lakes to an extent, but there are still cases of sea lamprey intrusion in the lakes.
To reduce the existence of sea lampreys in the great lakes, the Upper Midwest Environmental Sciences Center scientists are providing technical assistance to the Sea Lamprey Control Agents in the United States and Canada to support the re-registration of lampricides. They developed a controlled-release formulation of Bayluscide that is designed to kill sea lamprey in the bottom sediments where they reside without impacting other nontarget organisms. This new formulation is expected to reduce the populations of sea lamprey in Lakes Huron and Michigan by about 85%( www.umesc.usgs.gov).
Quagga or zebra mussels are also contributors to the great lakes’ habitat degradation. Introduced through ballast water like sea lampreys and other invasive. Zebra and Quagga mussels are small, fingernail-sized mussels native to the Caspian Sea region of Asia. They were introduced to the lake st.clair in 1988 by via ballast water from a transoceanic vessel, and since then, these mussels have spread to all of the great lakes.
Zebra mussels clog water intake of power plants and water treatment facilities and the cooling system of boat engines causing damage frequently. This specy of mussels has also help eliminate the native mussel species in the great lakes, and they are very prolific. “Female zebra mussels can produce as many as 1 million eggs per year. These develop into microscopic, free-swimming larvae (called veligers) that quickly begin to form shells. At about three weeks, the sand grain-sized larvae start to settle and attach to any firm surface using ‘byssal threads.’ They will cover rock, metal, rubber, wood, docks, boat hulls, native mussels, and even aquatic plants.”(ww.seagrant.umn.edu).
These mussels filter planktons from the great lakes, consume some and the rest of the plankton is combined with mucus as "pseudofeces" and discharged onto the lake bottom where it accumulates. This cause pollution of the lakes, and reduce the population of the planktons available for other fishes to feed on. Their cause of pollution also helps to poison fish larvae and the pseudo-feces produced are detrimental to the health of the aquatic animals. This is the result of introduction through ballast water, a route which the government thrive to reduce.
Pollution. This is also one of the major cause of habitat degradation. The deposition of chemicals, and unsafe materials which may clog the water, reduce the availability of oxygen and solar energy which aid the zoo planktons to photosynthesize are sources of pollution to the lakes. Also, some occurrences of pollution are caused by the invasives, for example zebra and quagga mussles, which discharge onto the bottom of the lakes harmful pseudofeces.
Pollution also contributed a great deal to the extinction of blue spikes, which suddenly dissapeared from the great lakes in the 20th century. Moreover, the industries also contribute to this in the sense that they produce harmful chemical bye products, which are not properly recycled and therefore pose a great threat to the biodiversity when deposited into the great lakes(Boyer, 1991).
In conclusion, life in the great lakes today is been turtured by introduction of invasive species, pollution, overfishing and other human factors. The governement and ecologists is taking measures to ensure that this problems are been resolved or reduced in order to restore the ecosystem to a time when the biodiversity was not been threatened by the mentioned factors.
References
Allardice, David R.; Steve Thorp. A Changing Great Lakes Economy: Economic and Environmental Linkages. Chicago, IL : United States Environmental Protection Agency, Region 5, 1995.
Boyer, Barry. No Place to Hide?: Great Lakes Pollution and Your Health. Buffalo, NY : Baldy Center for Law and Social Policy, 1991.
Christine Manninen, “Invasive species in the great lakes region,”Great lakes information Network, September 17, 2008 < http://www.great-lakes.net/envt/flora-fauna/invasive/invasive.html>
James Owen, “Overfishing is Emptying World's Rivers, Lakes, Experts Warn,” National Geographic News, December 1, 2005
Mona Rafeeq, “Degradation Of Great Lakes Habitat Threatens Fish Species,” Michigan Daily, January 22, 2004< http://www.michigandaily.com/content/speaker-degradation-great-lakes-habitat-threatens-fish-species>
Pam Belluck, "In Angler's Freezer Since '62, Fish May Refute 'Extinction'," New York Times, March 15, 1999.
Paul Schiff, "Blue Pike," Twine Line, October 1986.
"Blue Pike: Still Extinct from Lake Erie Waters,"Twine Line, July/August 1999.
The Associated Press, “Great Lakes Still Mired In Pollution,” Michigan Daily, September 13th, 2004< http://www.michigandaily.com/content/great-lakes-still-mired-pollution>
