Fróðskaparrit - 01.01.1995, Page 104

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WHALEWORM IN THE FILLETS OF SAITHE FROM FAROESE WATERS
search vessel “Magnus Heinason”. The fish
was caught by trawl in the standard estima-
tion of different Faroese fish stocks. The
saithe were filleted by hand on board and
deep frozen. The age was determined by
otoliths, but because of technical problems
this was not possible for the samples from
1992 and for one sample from 1993. On
shore, the right and the left fillets of each
fish were kept separated. The right and left
fillets of 305 fishes were divided into a dor-
sal and a ventral part. Further, each part
were divided into an anterior and a posteri-
or section (Fig. 2). Each of these sections
were digested seperately in pepsin-HCl
(21.7 g 1:2500 SigmaPepsin, 21.7 ml 25 %
HCl to 5 liter destilled water, pH 1.6) for 4-
6 h at 30-37 °C. Remaining fish muscles re-
ceived an additional digestion. The free ne-
matodes were sieved, carefully picked out,
counted and stored in 70 % ethanol for fur-
ther control. Sources of error are partially
digested bones who resemble nematodes.
Microscopical examination showed typi-
cally 1-2 lower counts of nematodes per
fish, but the macroscopic counts are used in
this report. Statistical analysis included a
paired two sample t-test when comparing
the right and left parts of the muscles.
Results
The nematodes collected from the diges-
tion procedure all tumed out to be Anisakis
simplex third-stage larvae. The terms used
in the following refer to Margolis et al.
(1982). Prevalence, expressed as propor-
Table 1. Date, position, number of fishes
(n), mean age of fishes and prevalence of
Anisakis simplex of saithe, Pollachius
virens, from Faroese waters.
d.u.: date unknown; n.k.: not known; tot:
total.
Talva 1. Yvirlit yvir tiknu sýnislutimar
av upsa av Føroya-leiðini; n: tal av
fiskum; Mean age: miðalaldur (ár) fyri
sýnið; prevalence: prosent-infektión við
Anisakis simplex; d.u. veiðitíð ókend;
n.k.: stað/alđur ókent/ókendur; tot:
tilsamans.
Date Position n Mean age Prevalance
(years) (%>
02.03.91 62°42’ N, 06° 07’ W 25 5,4 96,0
07.03.91 62° 19’ N, 08° 34’ W 22 5,3 90,9
10.03.91 60° 46’ N, 08° 29’ W 23 6,4 100,0
11.03.91 61° 27’ N, 07° 48’ W 26 4,8 100,0
25.03.91 62° 44’ N, 07° 00’ W 25 5,8 96,0
d.u.1991 n.k. 8 n.k. 100,0
tot. 1991: 129 mean: 96,9
d.u.1992 n.k. 40 n.k. 95,0
tot. 1992: 40 mean: 95,0
29.08.93 62° 29’ N, 06° 38’ W 4 2,3 50,0
30.08.93 62° 29’ N, 05° 18’ W 10 4,2 70,0
31.08.93 62° 10’N, 05° 37’ W 18 4,0 38,9
01.09.93 62° 36’ N,07°01’ W 9 3,2 77,8
02.09.93 62° 20’ N, 07° 50’ W 6 1,8 0,0
05.09.93 61° 05’ N, 06° 55’W 2 2,0 0,0
d.u. 1993 n.k. 49 n.k. 93,9
tot. 1993: 98 mean: 70,4
13.03.94 61° 40’ N, 05° 20’ W 11 4,0 63,6
15.03.94 61° 55’ N, 04° 52’ W 9 5.4 77,8
16.03.94 62° 25’ N, 05° 01’ W 26 4,2 65,4
tot. 1994: 46 mean: 67,4
tot. n. 313