Cold adaptation in Antarctic fish

There are only a few types of Antarctic fish. One of the most abundant groups are the Notothenioids, also referred to Antarctic cods (although they are not true cods). These fish have an antifreeze in their blood which prevents it from freezing despite their proximity to ice.

Another unique group of Antarctic fish are the icefish. These fish get their name from their pale, almost white colour. Icefish are unique as they are the only group of vertebrates (animals with a backbone) that do not have red blood cells (haemoglobin). Red blood cells are used to transport oxygen around the body; icefish transport oxygen within the blood plasma instead. Icefish are an important food source for seals, and are also harvested by commercial fisheries.

Tank full of Patagonian toothfish waiting to be tagged and released. Photo: AFMA

The Patagonian toothfish (Dissostichus eleginoides) is often regarded as the most important Antarctic fish, due to the extent of its commercial exploitation. Commercial fisheries catch these fish by trawling, and the setting of longlines. Longline fishing often results in the death of sea birds which are attracted to the baits; albatross deaths due to this are quite common in Antarctic regions. The Australian government therefore prohibits commercial fisheries from using longlines within the Australian Antarctic and sub-Antarctic Territories. Despite careful regulation and monitoring of commercial fisheries, stocks of patagnoian tooth fish are being threatened by illegal fishing.

Links -

• Research on Antarctic cod and icefish
• The patagonian tooth fish, efforts to monitor this commercial fishery, and illegal fishing.
• Fisheries research
• Patagonian toothfish
• Mackerel icefish
• Fisheries management