Why are the alewives dying?
There are several factors involved in the recent alewife die-off and the apparently large numbers that are washing up on the beaches. These factors are origin and life history of the fish, population abundance, and weather. Origin The alewife (Alosa pseudoharengus) is native to the Atlantic Coast; alewives entered the Great Lakes through the Welland Canal and made their way to Lake Michigan by 1949. Alewives are not well adapted to the osmotic stress associated with life in fresh water. Freshwater fish must constantly ‘pump’ water out of their bodies; fish that are well adapted to a freshwater environment have larger kidneys than their saltwater counterparts. Because of this physiological stress, alewives are rather sensitive to disturbances in their Great Lakes environment. Life History Alewives spend most of the year in the deeper waters of the open lake, but come into near shore waters in the summer when they are ready to spawn. Alewives begin to spawn when the water temperatures re
