Prevalence of trypanosome infections in marine fishes from western Norway

Abstract

Marine fishes from several locations along the west coast of Norway were examined for trypanosome infections. In total, 1640 fishes representing 63 species and 33 families were examined for trypanosome infections. Of these, 19 species of teleosts from eight families were found to be infected, mostly benthic codfish and flatfish in addition to Chelidonichthys gurnardus (L.) and Lophius piscatorius L. Trypanosomes in all fish species appeared to belong to a single form, considered identical to a trypanosome transmitted by the leech Calliobdella nodulifera (Malm, 1863). In the fjords near Bergen, west Norway, trypanosome infections appeared to be restricted to fishes caught deeper than 50 m, probably reflecting a limited bathymetric distribution of the leech vector. Available evidence suggests that the trypanosome parasitaemias decline and become undetectable in a year or less. Despite this, prevalence appeared unaffected by fish size in some species and increased with length in some slow growing species. Th...