Lake Michigan, it's said, sometimes gives up her dead shad, when the ice of Chicago comes early

Major, Bizarre Fish Die-Off Along Lakefront « CBS Chicago

Gizzard shad, members of the herring family, are more sensitive to drops in oxygen levels than most fish. And thick ice came early to Chicago harbors in December.
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Makauskas, who speculated that the young shad may not have built up enough reserves to survive the early onslaught of extreme cold, agreed the die-off is abnormal.