Abstract
Clavella adunca (STRØM, 1762) from the Barents Sea polar cod was studied. The general appearance and morphology of the appendages were similar to C. adunca f. iadda LEIGH-SHARPE, but the size of the trunk and cephalothorax were greater than those in other populations (mean trunk length 3.8 mm, width 3.0 mm, mean cephalothorax length 4.3 mm). Most of the parasites (94 %) were found on the fins.
Parasites were found in the whole distribution area of the polar cod, but were most frequent in the eastern part of the Barents Sea. Of 42 samples 39 contained infected fishes. The distributions of the parasites on the hosts were always overdispersed and negative binominal distributions proved to be a good empirical model of the observed distributions. The infection rate was higher during winter than during summer. No correlation between the infection rate and the age of the host was observed.