Antifreeze Peptides and Glycopeptides in Cold-Water Fishes

(-1.9°C), a temperature well below the freezing point of a' typical marine teleost (-O.8°C) (5). This one degree difference between environment and body fluid freezing point is large enough to result in freezing because supercooling in the presence of ice cannot occur (74). Freezing of the body fluids or tissues of fishes has been shown in all cases to lead to death, although several hours may intervene between thawing and death. Two diff erent strategies by which fishes avoid freezing when their habitats are cooled below their freezing points are recognized. The first concerns behavioral responses. Some shallow-water summer inhabitants migrate offshore to warm water (15) while others move into deep (100 m) cold water and overwinter at a temperature of -1.9°C in a supercooled state. One degree of supercooling is small and appears to be metastable at these depths where the waters are ice free. In the shallow ice-laden waters of the' polar oceans many fishes spend