LOCALadk Magazine
Issue link: https://localadkmagazine.uberflip.com/i/434744
I magine being a trout during an Adirondack winter. You're probably pretty small - likely under two pounds. Predators patrol the ice hoping to snatch you. If they don't get you, the ice itself might. It's so cold, you don't want to move. Not much food floats down the current. Best to hunker down and wait for spring. Winter is the most dangerous time for trout in rivers. They basically hide, going into a state of torpor until it's safe to come out. Torpor is not hibernation per se. It is a state of decreased physiological activity usually a result of reduced body temperature and metabolic rate. It enables an animal to survive when food is scarce. In the case of fish, which are cold-blooded and thus have a body temperature which changes with their external environment, their metabolism and activity levels slow down as water cools. Once the water wanes below about 38 degrees (F), if a trout is forced to move around a lot to escape predation, to go after food (an instinct) or because of unstable habitat such as when ice is forming or breaking up, the energy they expend could leave them mortally weakened. When there's an ice roof overhead, their surroundings are more stable so they're less active, thus greatly increasing their chance of survival. Add a foot of snow, turning off the lights, and fish stay put. Not moving is the key to survival under the crystal ceiling. They should not even move to feed, but if food floats by, fish are enticed to move whether they're hungry or not. During the winter, the buffet in the water column is mainly tiny immature insects at their smallest developmental stage, known as instars. Trout filter instars out of the water through their gills, but never in much volume because they are so small - like collecting grains of sand in your hand with your fingers spread apart - so instars do not provide much nutrition. A trout might not starve to death trying to eat instars, but they lose body mass. Their body condition deteriorates until they can't resist Under Ice What happens to trout when rivers freeze? Story by Lisa Densmore Ballard The most dangerous time of year for trout is during ice up and ice out when frazil ice is present in the water. " " 20 Winter 2014