Hibernation-like behavior in Antarctic fish -- on ice for winter

Mar 05, 2008
The 'Antarctic Cod' (Notothenia coriiceps)
The 'Antarctic Cod' (Notothenia coriiceps) became isolated from its warmer water cousins around 30 million years ago when the Antarctic circumpolar current was formed. Credit: Dr Hamish Campbell

Scientists have discovered an Antarctic fish species that adopts a winter survival strategy similar to hibernation. Reporting this week in the journal PLoS ONE, the online journal from the Public Library of Science, scientists from British Antarctic Survey (BAS) and the University of Birmingham reveal, for the first time, that the Antarctic ‘cod’ Notothenia coriiceps effectively ‘puts itself on ice’ to survive the long Antarctic winter.

The study showed that the fish activate a seasonal ‘switch’ in ecological strategy – going from one that maximises feeding and growth in summer to another that minimises the energetic cost of living during the long, Antarctic winter. The research demonstrates that at least some fish species can enter a dormant state, similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits. Scientists already know that Antarctic fish have very low metabolic rates and blood ‘antifreeze’ proteins that allow them to live in near-freezing waters. This study demonstrates that Antarctic fish - which already live in the ‘slow lane’ with extremely low rates of growth, metabolism and swimming activity - can in fact further depress these metabolic processes in winter.

Lead author Dr Hamish 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. 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.”

Dr Keiron Fraser from BAS says,

“This is our first insight into how these fish live in winter. We have for the first time in the Antarctic, used cutting edge technologies combining tracking of free swimming fish in the wild and heart rate monitors to allow us to investigate just how these animals cope in winter with living in near freezing water and almost complete darkness for months on end. It appears they utilise 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. The interesting question we still have to answer is why these fish greatly reduce feeding in winter when food is still available.”

Why these fish chose to adopt this hibernation-like strategy during winter is currently unclear, but it presumably provides energetic benefits. The traditional views of hibernation are being challenged constantly. This study introduces a new group of animals that appear to utilise a hibernation-like strategy that allows them to survive during the long winters in one of the harshest environments on Earth.

Source: British Antarctic Survey

Explore further: Experts 'grasping at straws' to save near-extinct rhino

add to favorites email to friend print save as pdf

Related Stories

Spy on penguin families for science

Sep 17, 2014

Penguin Watch, which launches on 17 September 2014, is a project led by Oxford University scientists that gives citizen scientists access to around 200,000 images of penguins taken by remote cameras monitoring ...

New discovery finds missing hormone in birds

Mar 24, 2014

University of Akron researchers discovered leptin in the mallard duck, peregrine falcon and zebra finch, marking the first time the hormone has been found in birds.

Polar ecosystems vulnerable to sunlight

Jul 31, 2013

(Phys.org) —Slight changes in the timing of the annual loss of sea-ice in polar regions could have dire consequences for polar ecosystems, by allowing a lot more sunlight to reach the sea floor.

Under-ice habitat important for Antarctic krill

Mar 08, 2012

The importance of the under-ice habitat for Antarctic krill was probably under-estimated in the past and emphasise the susceptibility of this ecological key species to changes in the sea ice habitat induced ...

Recommended for you

'Hairclip' protein mechanism explained

12 hours ago

Research led by the Teichmann group on the Wellcome Genome Campus has identified a fundamental mechanism for controlling protein function. Published in the journal Science, the discovery has wide-ranging implications for bi ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

superhuman
not rated yet Mar 05, 2008
They hibernate cause they don't like those dark cold winters, if I were one i know i would too! Pity we humans can't hibernate through winter.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.