Dams Cause Fish Population To Decrease
Dams were built along the Concord River to increase crop production and also to provide a source of power for operating mills. By the 19th century, the native population of shad and alewife became extinct, because the dams prevented the mature fish from returning upstream to spawn. Alewife and other anadromous fish are migratory. They hatch in fresh water, make their way to the sea to grow, then return as adults to fresh water to spawn, usually near where they had hatched. This instinct is imprinted within the fish when it is born. So, when the route upstream became blocked, the cycle was broken. The Millpond Dam in North Billerica is just one of many blockages that caused the alewife population to collapse on the Concord River. At this point, water was diverted north to Lowell and south to Charlestown to run the Middlesex Canal.
Read more about this topic: Concord River
Famous quotes containing the words fish, population and/or decrease:
“My face is muffled in my mother’s clothing. Her rhinestones injure me. See: my feet are going. Fish flee the forefinger of my aunt. The sun streams over the geraniums. What has this to do with what I feel, with what I am.”
—William Gass (b. 1924)
“America is like one of those old-fashioned six-cylinder truck engines that can be missing two sparkplugs and have a broken flywheel and have a crankshaft that’s 5000 millimeters off fitting properly, and two bad ball-bearings, and still runs. We’re in that kind of situation. We can have substantial parts of the population committing suicide, and still run and look fairly good.”
—Thomas McGuane (b. 1939)
“The increase in wisdom can be measured precisely by the decrease in bile.”
—Friedrich Nietzsche (1844–1900)