Fróðskaparrit - 01.01.1995, Page 107

WHALEWORMIN THE FILLETS OF SAITHE FROM FAROESE WATERS
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Year 1991 1992 1993 1994 Totals:
infected físhes 125 38 68 31 262
not inf. físhes 4 2 22 15 43
total right 4,96 4,71 4,40 0,97 4,31
total left 8,70 8,87 5,63 1,71 7,10
stat. diff. *** * n.s. n.s. ***
right A 4,09 3,05 1,92 0,15 2,72
left A 7,31 5,95 2,29 0,61 4,64
stat. diff. ** n.s. n.s. * ***
right D 0,52 1,23 1,00 0,41 0,74
leftD 0,91 1,98 1,61 0,50 1,18
stat. diff. * n.s. n.s. n.s. **
right B 0,13 0,15 0,19 0,02 0,13
leftB 0,19 0,23 0,24 0,02 0,19
stat. diff. n.s. n.s. n.s. n.s. n.s.
right C 0,07 0,05 0,21 0,07 0,11
leftC 0,02 0,28 0,11 0,02 0,09
stat. diff. n.s. n.s. n.s. n.s. n.s.
of the standard deviation compared to the
mean values (Table 2) reflect a general pat-
tem in parasitologic examination, the ten-
dency of high levels of variation. A slight
decrease in infection levels with the time
for the same age-group can nevertheless be
seen in Table 2. This may be explained by
an increase in the immune response effect
from the infected fishes, as is suggested by
Priebe et al. (1991). Decreasing infection
levels in saithe from length group 40-49 cm
are also reported by Scott (1985).
The pooling of all fishes examined in
Fig. 2, showing the distribution of the
Anisakis simplex larvae in the fillets could
be critisized. However, in an extensive sta-
tistical analysis Novotny and Uzmann
(1960) found no dependence between age
of fish or geographical place, and the distri-
bution of Anisakis sp. larvae in chum
salmon, Oncorhynchus keta.
The higher abundance found in the left
side of the fish is striking (Fig. 2 and Table
3). The ventral parts A, D were statistically
Table 3. Values of the mean for paired two
sample t-tests for the difference in the num-
ber of Anisakis simplex larvae in the right
and left sections of saithe fillets, A, D, B, C,
as in Fig. 2; *: p<0.05; **: p<0.01;
***: p<0.001; n.s.: not significant; stat. diff.:
statistical difference (the table is comparing
infected fishes only).
Talva 3. Tøl fyri miðalvirðir frá paraðari
t-test fyri munin í tali av Anisakis simplex
ormverum í vinstru (left) og høgru (right)
pørtunum av upsaflaki A, D, B, C, eins í
Mynd 2. *: p<0.05; **: p<0.01;
***: p<0.001; n.s.: ikki signifikantur munur;
stat. diff.: hagfrøðiligur munur
(talvan samanber bert fiskar, ið eru
infiseraðir).
different when comparing the right and the
left side, but not the dorsal parts B and C.
Brattey and Bishop (1992) report the same
difference for Anisakis simplex in the fillets
of cod from Canadian waters. They also
found significant difference between the
bellyflaps (referred to as “the napes”). A
similar distribution for Pseudoterranva de-
cipiens in Canadian cod is reported by
Brattey et al. 1990.
Why the two different fish species saithe
and cod do have uneven distributions of the
nematodes in the musculature remains to
be explained. One possible reason for the
difference between the left and the right
side could be the assymetry of the organs
inside the body cavity. But this hypothesis
is difficult to prove by experimental infec-
tion.
The comparison of saithe from Faroese
waters with other areas in the North At-
lantic is justified in Joensen and Táning
(1970), who report considerable migrations
to and from the Faroe area to Icelandic wa-