Bears do it, but did you know that fish can hibernate, too?

William Atkins
Wednesday, 05 March 2008 18:30

Science - Biology

UK researchers have found that an Antarctic fish hibernates during cold winters.      

The fish species Notothenia coriiceps, commonly called Black rockcod, is a type of cod icefishes, or ray-finned fish that live in the cold Southern Ocean and other cold waters around Antarctica.

These fishes have an antifreeze-like protein in their blood and have much fat in their bodies to help insulate themselves from the cold waters they live in. The antifreeze protein seems to also help place them in a dormant state similar to hibernation.

This hibernating fish is the first of its kind discovered by scientists.

In fact, one of the authors of the study, Hamish A. Campbell (formerly at the University of Birmingham, UK, but now at University of Queensland, Australia) said, “Hibernation is a pretty complex subject. Fish are generally incapable of suppressing their metabolic rate independently of temperature. Therefore, winter dormancy in fish is typically directly proportional to decreasing water temperatures."

Campbell continues, "The interesting thing about these Antarctic cod is that their metabolic rates are reduced in winter even though the seawater temperature doesn’t decrease much. It seems unlikely that the small winter reductions in water temperature that do occur are causing the measured decrease in metabolism. However, there are big seasonal changes in light levels, with 24 hour light during summer followed by months of winter darkness – so the decrease in light during winter may be driving the reduction in metabolic rates.” [EurekaAlert!: “Hibernation-like behavior in Antarctic fish—on ice for winter”]

This dormant state is similar to hibernation in land animals like bears.

In fact, another author in the study, Kairon P.P. Fraser, of the British Antarctic Survey, stated, “It appears they utilize the short Antarctic summers to gain sufficient energy from feeding to tide them over in winter. The hibernation-like state they enter in winter is presumably a mechanism for reducing their energy requirements to the bare minimum.” [Reuters: “Scientists find hibernating fish in Antarctic”]
 
Fraser, Campbell, Stuart Egginton (University of Birmingham Medial School), Charles M. Bishop (University of Bangor, Wales) and Lloyd Peck (British Antarctic Survey) conducted this study over two Antarctic summers and one entire winter period at Rothera Research Station.

They published their findings (“Hibernation in an Antarctic fish: on ice for winter”) in the journal PLoS ONE, the online journal from the Public Library of Science.