The Annual Alewife Die-Off, Montrose Pier, Uptown Chicago, 1970

I came across a reference to the Lake Michigan Alewife recently, and how they used to be a huge nuisance to the neighborhoods along the lake.

An alewife—not to be confused with the medieval profession of beer brewing—is a type of fish. They are common in the waters off New England, but around the 1930s they invaded the Great Lakes, using the Welland Canal and bypassing Niagra Falls. They were feasted upon by lake trout, and so were not much of a nuisance, until overfishing and the invasion of the sea lamprey wiped out much of the trout population.

Alewife numbers grew and grew, and their population began to peak in the sixties. They are an edible fish, so this doesn't sound like a bad thing, does it?

The problem with them was their annual die-off. Hundreds of millions of fish would turn belly up in the water each year (there is even a report of a forty-mile-long flotilla of dead fish stretching across the lake). Hundreds of thousands would suddenly wash up on Chicago's beaches. And from what I've heard, they stank. Just imagine what thousands of rotting fish would smell like! There were so many that the city needed bulldozers to clean up the mess.

So, how did the city fight back? Salmon were added to the lake to eat the alewifes, and voila! No more problem.

Or is there? At present, the lake's salmon populations are being threatened by another fish species...the Asian carp.

Editor's note: I found this note on Wikipedia about declining Alewife populations.

"Alewife populations have exhibited drastic declines throughout much of their range. Several threats have most likely contributed to their decline, including loss of habitat due to decreased access to spawning areas from the construction of dams and other impediments to migration, habitat degradation, fishing, and increased predation due to recovering striped bass populations. In response to the declining trend for alewife, the states of Massachusetts, Rhode Island, Connecticut, Virginia, and North Carolina have instituted moratoriums on taking and possession. The alewife is a US National Marine Fisheries Service Species of Concern."