INFECTIONS OF DIPHYLLOBOTHRIUM-DENDRITICUM, DIPHYLLOBOTHRIUM-DITREMUM(CESTODA), AND CYSTIDICOLA-FARIONIS (NEMATODA) IN A NORTH NORWEGIAN POPULATION OF ARCTIC CHARR (SALVELINUS-ALPINUS) DURING WINTER
R. Knudsen et A. Klemetsen, INFECTIONS OF DIPHYLLOBOTHRIUM-DENDRITICUM, DIPHYLLOBOTHRIUM-DITREMUM(CESTODA), AND CYSTIDICOLA-FARIONIS (NEMATODA) IN A NORTH NORWEGIAN POPULATION OF ARCTIC CHARR (SALVELINUS-ALPINUS) DURING WINTER, Canadian journal of zoology, 72(11), 1994, pp. 1922-1930
Infections of the parasites Diphyllobothrium dendriticum, Diphylloboth
rium ditremum, and Cystidicola farionis in Arctic charr (Salvelinus al
pinus) from Takvatn, northern Norway, were followed throughout a 9-mon
th overwintering period. The relative density of all three parasite sp
ecies increased with the age of the host in response to ontogenetic sh
ifts in habitat and food of Arctic charr in the lake. Our results indi
cate that some recruitment of the three parasite species, particularly
D. ditremum, takes place during the winter. However, winter parasite
recruitment was lower than in the ice-free season. In spite of high pa
rasite infection in some individuals, no strong indications of parasit
e-induced host winter mortality were found for any of the three specie
s. Low overwintering mortality of heavily parasitized charr may be con
nected with a stock-reduction program in the lake that has improved th
e conditions of the fish, and the residual stock is probably less affe
cted by parasites.