Aquatic Life in Winter                               Bob Gregorski

Ever wonder about what fish and other aquatic life were doing after braving snow, ice and sub-freezing air and water temperatures.  In my younger years, I would spend some time during the winter fishing rivers and streams for trout.  One year I remember catching my first riverine trout of the year in the Pomperaug River near the well house in Woodbury.  The beautiful 14 brown nailed my #10 Bruised Butt bucktail and put up a good fight before I released it.  Fish eat every day. 
Fish are cold-blooded (poikilothermus). Which means that they do not generate their body heat.  They adjust to the water temperature they are in by eating and moving less.  Moving less slows down their digestion and need for food.  The oxygen levels vary greatly during the winter.  Although cold-water holds more dissolved oxygen than warm water, there is less oxygen produced by plants (photosynthesis) in the winter due to less direct sunlight (less daylight and snow cover).  Ice cover stops the exchange of oxygen from the air with water. Winter and summer are the two seasons when riverine fish mortality are highest due to insufficient amounts of dissolved oxygen in the water and inappropriate water temperatures. 
Most of the state’s waters are home to frogs, salamanders and turtles.  The metabolism of these aquatic creatures decreases as the temperature of their surroundings decreases.  They know when winter is approaching and seek refuge through the subfreezing temperatures.  Just as antifreeze and windshield solutions protect vehicles, frogs produce their own fluid to protect them from freezing.  Some frog species (bullfrog and leopard) breathe through their skin and remain underwater under mud or debris. Other species (peepers and wood frogs) can tolerate freezing. They spend the winter under ground or beneath leaf piles.  Their skin turns to ice crystals, but critical body parts are protected by frog antifreeze.