Thousands of gizzard shad are going belly up along Chicago’s lakefront in a large die-off that’s left many of the fish frozen in the ice along the city’s harbors.
Lake Michigan Program biologist Dan Makauskas tells the Chicago Sun-Times that gizzard shad aren’t a very tough variety of fish. They’re members of the herring family, and they’re more sensitive to drops in oxygen levels than most fish.
Makauskas says the young fish may not have built up enough reserves to withstand the early onslaught of extreme cold that hit the area.
via Thousands of fish dead along Chicago lakefront – chicagotribune.com.
The dissolved oxygen levels in water depends on many factors. The temperature, depth of water source and the water movement contributes to the oxygen levels. The fluctuation in natural cycle can cause imbalance in oxygen levels. Here the extreme cold weather has caused this damage.