An influence of the parasite Clavella adunca (Strøm, 1762) (Copepoda Parasitica: Lernaeopodidae) on the cod (Gadus morhua L.) from North-west Atlantic waters

Abstract

Over the years 1970 and 1974 there were carried out studies on the prevalence of the Clavella adunca (Strøm, 1762) parasite on the cod (Gadus morhua L.) from North-west Atlantic (Labrador and New Founland fishing grounds). The growth rate and condition of 4454 cod specimens was studied. The length-weight relationship, condition, and growth parameters of infested and non-infested fishes were calculated. The calculations have shown that young fishes infested by Clavella adunca parasite had higher average weight and condition than noninfested ones of the same length. On the other hand, older infested fishes (above 6 years of life) had average weight and condition lower than noninfested specimens. The author′s own attempt to explain this paradoxical phenomenon is presented.