“Maryland freezes every winter...”
That is what I am remembering. Last year was very cold and I don’t recall a fish kill. I remember when they had to cut through the channels as well. No fish kill. Interesting?!
It may have to do with the speed of the temperature change. Many species start their migration when water temperature hits a certain level; perhaps this year's drop was sudden, where a normal year is more gradual. Instead of slowly passing the temperature that triggers migration, it may have shot right by it, leaving the fish unable to cope.