SEASONAL CHANGES IN THEINFECTION OF YOUNG SAITHE
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J F M A M J J A S O N D
Fig. 2. a. The number offemales (white) and males (black) in samples of 1-year old saithe.
Talið av kvennfiski (grátt) og kallfiski( svart) hjá 1-ára gomlum seiði.
Fig. 2. b. The number offemales (white) and males (black) in samples of2-year old saithe.
Talið av kvennfiski (grátt) og kallfiski (svart) hjá 2-ára gomlum seiði.
cephalean Echinorhynchus gadi were re-
covered from the gut lumen (adults) or in
the pyloric caeca (larvae). The prevalence
and intensity of infection are shown in Figs.
4 and 6. A single record was made of the
crustacean laerneopodid ectoparasite Clav-
ella sp. and an unknown cestode plerocer-
coid. As the stomach is not included in this
study, no digeneans have been recorded.
The results in this study showed a general
increase through one calendar year in the
prevalence of infection of young saithe
with A. simplex. The mean intensity of in-
fection was increasing for the 1-year old
saithe, but seemed stable for the 2- year old
saithe. Similar patterns, but at lower levels
were revealed for P. decipiens and Contra-
caecum sp. How can these fmdings be in-
A population of fishes which is infected
by a population of parasites may be so in
two principal ways. Either the infection is
continuous (an even or random distribution
is presumed for the infected intermediate
host(s)), or the infection is non-continuous
(a discrete or uneven distribution of the in-
fected intermediate host). In the first case
the prevalence of infection is expected to fit
a simple linear function, but in the latter
case a more complicated, non-linear func-
tion could be expected.
The prevalence of infection for Anisakis,
Pseudoterranova and Contracaecum in this
study appear to increase linearily with time
(Fig. 4a), so the process of infection for
saithe in this area most likely is continuous.