ON THE EXAMINATION AGAINST THE PARASITES OFANTARCTIC KRILL, EUPHAUSIA SUPERBANOBORU KAGEi, KAZUHITO ASANO AND MICHIE KIHATADivision of Parasitology, the Institute of Public Health, Tokyo

In order to obtaine more information on the nutritive value as human foods oranimal feeding stuffs and to estimate any existence of the potential health hazards,
samples prepared from frozen krill were examined against the parasites.
MATERIALS AND METHODS
Antarctic krill, Euphausia superba were collected by use of the plankton nets in
Antarctic Ocean by a catcher boat of Taiyo-Gygyo K.K. The localities, number and size of Antarctic krill examined are shown in Table 1. The krill wereimmediately stored at -40°C on the boat. These frozen samples were broughtin our laboratory. The krill were pressed between two glass plates, and were
inspected by the binocular dissecting microscope ( 1Ox) against the parasites.
TABLE I.

SURVEY OF THE PARASITES IN ANTARCTIC KRILL, EUPHAUSIA SUPERBA
at Antarctic krill

No.

W I-1
W I-2
W I-3
W I-4
W I-5
W I-6
TotalDateLocality

59°34 1S 49°54 1E1975-12-1
1975-12-15 62°47 1S 64°39 1E
62°22 1 S 83°45 1E
1976-1-265°14 1S 59°15 1E
1976-1-15
1976-2-1
65°35 1S 55°381E
1976-2-1365°30 1S 56°02'E

Body length*(SD)**

Body weight*(SD)**

No.
exam.

No. positive ofparasites

59.1 (47-64)(3.56)
50. 7 (41-60)( 4.89)
45.3(35-57)(5.96)
47.5(35-58)( 4.83)
46.5(35-55 )_(5.27)
46.7 (34-60)(5.74)

1.21 (0.80-1.40)(0.15)
0.82(0.40-1.30)(0.21)
0.50(0.30-0.95)(0.17)
0.68(0.35-1.10)(0.21)
0.50(0.15-1.08)(0.19)
0.60(0.20-1.20)(0.22)

2,823
9,823
I 1.576
9,754
11,406
10,40655,2950000000*: No. of examined specimens=50; mm. and gram.
**: SD=standard deviation

RESULTS AND DISCUSSIONAs shown in Table 1, 55,295 specimens of Euphausia superba in total examined were
negative for the parasites at all.
Although the larvae of many species of helminthic have been found in vari~us
marine invertebrates (Sarsa, 1885; Lebour, 1917; 1923; Jepps, 1937; UspenskaJ~,1960; Rees, 1961 ; Dollfus, 1964; Oshima et al., 1969; Overstreet, 1970; Komak1,1970; Vivares, 1971 ; Reimer et al., 1971 ; Smith, 1971 ; Shimazu, 1971; 1972;
1975a, b; Shimazu and Oshima, 1972; Ramadevi and Rao, 1974; Kagei, 1974;
Sci. Rep. WhalesRes. Inst.,

No. 30, 1978, 311-313

KAGEI, ASANO AND KIHATA

312

Sluiters, 1973; 1974; Shiraki et al., 1976), the parasites of the health hazards werethe larvae of Anisakis spp. and Terranova sp. (Anisakinae: Nematoda), and thelarvae of Anisakis spp. and Terranova sp. have been found in various invertebrates
including the euphausiids (Uspenskaja, 1960: Thysanoessa raschii; Oshima et al.,1969, Shimazu and Oshima, 1972: Thysanoessa raschii, Thysanoessa longipes, Euphausia pacifica; Smith, 1971 : Tlrysanoessa inermis, Thysanoessa longicaudata; Kagei,
1974: Euphausia pacifica; Sluiters, 1973, 1974: Thysanoessa raschii), the amphipoda(Uspenskaja, 1960: Caprella septentrionalis), the branchurans (Decapoda) (Uspenskaja, 1960: Hyas araneus), arrow worms (Chaetognatha) (Reimer et al., 1971)
and Prawns (Shiraki et al., 1976: Pandalus borealis and P. kessleri) (Banning, 1970:Meganyctiphaens norvegica). However, according to the results of many previous
papers and this examination, Type-I larvae of Anisakis are recognized to be heavily
infected in the northern euphausiids, but the infection rates are decreased graduallyin the lower latitude (Kagei, 1974 ). It is interesting that this geographical distribution is by the quantity of infected final hosts, the heavily infection with Anisakis
larvae in the northern fishes and inhabited quantity of euphausiids, and the examination of 35,319 Euphausia superba from the Antarctic ocean by Kagei ( 1974)
was negative for the larvae of Anisakis and other parasites. In the present examination, Euphausia superba from various parts of the Antarctic ocean is also negative
for the larvae of Anisakis. This is interesting to related to that the present ofAnisakis spp. in marine mammals from the Atlantic Ocean was not occured as
found at the report of Kagei and Kureha (1970).
ACKNOWLEDGMENTS
We thank the Director and staff of the Taiyo-Gyogyo K.K. and Japan Marine
Fishery Resource Research Center whose given cooperation and help for theextensive collections of available specimens for these over all studies.
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Sci. Rep. Whales Res. Inst.,
No. 30, 1978.