Hibernation - Dormancy in Fish

Dormancy in Fish

Fish are ectothermic, and so, by definition, cannot hibernate because they cannot actively down-regulate their body temperature nor their metabolic rate. However, they can experience decreased metabolic rates associated with colder environments and/or low oxygen availability (hypoxia). They can, however, experience dormancy. For a couple of generations during the 20th century it was thought that basking sharks settled to the floor of the North Sea and became dormant. Research by Dr David Sims in 2003 dispelled this hypothesis, showing that the sharks actively traveled huge distances throughout the seasons, tracking the areas with the highest quantity of plankton. The epaulette sharks have been documented to be able to survive for long periods of time without oxygen, even being left high and dry, and at temperatures of up to 26 °C (79 °F). Other animals able to survive long periods without oxygen include the goldfish, the red-eared slider turtle, the wood frog, and the bar-headed goose. However, the ability to survive hypoxic or anoxic conditions is not the same, nor closely related, to endotherm hibernation.