Blood viscosity in arctic fishes

The blood viscosity of arctic char, Salvelinus alpinus, and shorthorn sculpin, Myoxocephalus scorpius, from the arctic (74 degrees 42'N) was measured with a cone-plate viscometer. Blood viscosity of the two arctic species was considerably lower, less shear rate dependent, and less temperature dependent than the blood of winter flounder (Pseudopleuronectes americanus) from more temperate waters. The rheological properties of the arctic fish blood would minimize blood flow resistance and thus be advantageous at the low temperatures (0 degree C) characterizing their environment.