Really good question Bo - I am assuming it is temperature related, but have often wondered if low DO events due to snow cover might drive RES upwards in the water column seeking higher concentrations of DO, which, unfortunately for them, is also much colder water, to the degree it's lethal. We are nearing the Northern range of RES in Nebraska - I anticipate some morts every Winter, just hope they aren't "special" fish like Shorty's was.

Many men go fishing all of their lives without knowing that it is not fish they are after. ~ Henry David Thoreau

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