The icefish is an evolutionary exception. It has no haemoglobin in its blood, the substance used by vertebrates for oxygen transport. This gives the fish its pale and weak appearance. Hauke Flores of Alterra discovered that the fish has a clever strategy for making sure its food is presented on a dish, thus saving itself energy.
Flores, whose findings were published in Polar Biology earlier this year, is pleased that his research has shed some light on the ecology of this fascinating icefish. Biologists have long been puzzled about how the icefish can survive without haemoglobin. It was already known that the fish has a relatively large heart for its body weight, which improves its circulation.
Flores also discovered that another icefish, the Mackerel icefish (Champsocephalus gunnari), does not employ the same eating strategy as the Blackfin icefish. The Mackerel icefish eats almost only krill. It is not yet known whether the Mackerel icefish also uses a similar method to limit its energy expenditure to the Blackfin icefish.
Flores research’ was partly fundamental, but was also carried out in relation to the Convention on the Conservation of Antarctic Marine Living Resources (1982). One of the main aspects of the convention is monitoring of the krill reserves in Antarctic waters, in particular for the whale population. Flores has estimated how much krill is consumed each month by the icefish around the South Shetlands and Elephant Island, and puts the figure at around a thousand tons. According to Flores this amount does not pose a threat to other krill eaters. The whale population is probably more threatened by Russian and American krill fishing activities.