Physiology of feeding and starvation tolerance in overwintering freshwater fishes

Synopsis

Overwintering conditions in north temperate lakes characterized by low temperatures, low oxygen tensions, and, for some species, low food supplies are thought to have effects on fish species composition and recruitment. Examination of respiration and excretion rates of various overwintering species as well as measurements of the amount of lipid stored in visceral and muscle tissue during the winter months suggest feshwater fishes can be divided into groups based on their tolerance to starvation. Cold-water species, such as yellow perch, Perca flavescens, which have low preferred body temperatures throughout the year (13°C or lower), are very sensitive to starvation during winter months. This species feeds actively throughout much of the winter and stores lipids primarily in the viscera and gonads prior to early spring spawning. Warm water fishes, such as largemouth bass, Micropterus salmoides, which have a high preferred body temperature during the summer (23–26°C) and appear not to feed at low winter temperatures, have an intermediate tolerance to starvation during winter months. Largemouth bass store lipids both in muscle and visceral tissue, and winter starvation tolerance is dependent on the amount of stored lipids. Fishes that are physiologically intolerant of long periods of food deprivation and actively feeding during the winter (e.g. yellow perch) are thus distinguished behaviorally and physiologically from fishes that are more tolerant of prolonged starvation (e.g. largemouth bass) and tend to be less active during the winter months.