Water Ecology

At first glance the water of the Great Lakes looks crystal clear and empty of any life but varieties of bass, trout, salmon, whitefish, and walleye, which are plentiful and make for an exciting fishing outing and (hopefully) a filling meal at the end of the day. However, this is just the tip of the berg when it comes to what creatures call these waters home, and without the vast food web of these smaller fishes, crustaceans, planktons, mollusks, diatoms and algaes, there would be no salmon, whitefish or bass.

On the near microscopic level we find algaes, diatoms, rotifers, and flagellates, and these are everywhere in very large numbers. They build the foundation for all aquatic life that exists here. The waterfleas, amphipods, freshwater (opossum) shrimp, zebra mussels and mollusks are all supported by these near microscopic organisms. Next up on the food chain we see yellow perch, sculpins, crawfish, alewifes, smelt, and goby. These are the food for the salmon, whitefish, bass etc..

When there are high concentrations of nutrients for algae and other plant life, as is found in fertilizers that washes from the farmland into the lakes, the increased growth in plant life can deplete the oxygen levels and quickly the fish populations will decrease dramatically. This was seen in the Black Sea, in Lake Erie, and at the mouth of the Mississippi River in the Gulf of Mexico. Huge plumes of algae make the waters uninhabitable for fish, but (as in the case of the black sea) this process can be reversed and the fish populations restored.

The fish native to the Great Lakes were the lake trout, whitefish, sturgeon, musky, and yellow perch, and later once navigation was opened into the lakes came the carp, salmon, zebra mussels, and the lamprey eel. The fishery boom occurred in the mid 19th century, but with the boom of industry and population increase came poorer water quality and over fishing, and the fishing industry all but collapsed. Only in the last few decades has the focus on taking care of our freshwater resource begun to show in the return of fish populations, and when you go out for a charter fishing trip or dip your line from your own boat and pull in a healthy lake trout or salmon, give thanks to the dedicated people who have fought for responsible industry practices, otherwise we may have not seen a return of the fish at all.