ACOUSTIC INSTRUMENTS
Two SIMRAD scientific echo sounders, EK 400/38 kHz and EK 400/120 kHz were used during the survey for estimation offish density. The EK 400/38 was coupled to a digital integrator QD as well as to an analog integrator QM. The performance of the instruments were measured by calibrations on a standard copper sphere. The details of the instrument settings used are as follows:
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EK 400/38 |
EK 400/120 |
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Range |
0-100 m or 0-250 m |
0-100 m |
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Transmitter |
High (5000 W Nom) |
High (1250 W Nom) |
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Bandwith |
3.3 kHz |
3.3 kHz |
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Pulselength |
0.5 ms |
1 ms |
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TVG |
20 log R |
20 log R |
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Attenuator |
20 dB |
0 |
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Rec. gain |
7 |
5 |
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Transducer |
8 × 8 ceramic |
Ceramic 10 cm |
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Calibrations of acoustic system: |
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Time-location |
Transd. 30x30 |
ES |
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SL+VR |
Instr. const. |
SL+VR |
Instr. const. |
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12/11/87 Costa Rica |
141.1 |
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134.3 |
5.1 |
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20/02/88 Gulf of Cariaco |
141.2 |
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135.6 |
3.8 |
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1 ms |
0.5 ms |
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03/06/88 Gulf of Cariaco |
141.2 |
1.01 |
2.38 |
135.0 |
4.15 |
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02/09/88 Gulf of Cariaco |
141.0 |
1.24 |
2.64 |
134.9 |
4.56 |
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25/11/88 Gulf of Cariaco |
141.0 |
1.02 |
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135.6 |
4.33 |
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18/02/89 Angola |
141.2 |
1.11 |
2.49 |
135.67 |
3.46 |
Temperature, salinity and oxygen were sampled at standard depths with Nansen bottles. Oxygen was measured with the Winkler method and salinity determined with an inductive salinometer. Surface temperature was recorded at 4 m depth with a thermograph.
FISHING GEAR
Bottom trawl: High opening shrimp and fish trawl with net headline 31 m (floatline), foot-rope 47 m, gear with 12 cm diameter roller disks, 40 m sweeps, estimated headline height 6 m and distance between wings during towing 18-20 m.
Pelagic trawl: Type “Harstad-trawl”, width about 30 m, vertical opening 10-15 m.
Cod ends of trawls with fine meshed inner lining.
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Survey assignment DR. FRIDTJOF NANSEN |
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Period |
Assignment |
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FEB 1975-NOV 1976 |
NW ARABIAN SEA |
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JAN-JUN 1977 |
PAKISTAN |
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AUG 1977-JUN 1978 |
MOZAMBIQUE |
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JUL 1978 |
SEYCHELLES |
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AUG-SEP 1978 |
SRI LANKA |
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APR-JUN 1979 |
SRI LANKA |
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JUL-AUG 1979 |
OMAN AND ADEN GULFS |
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SEP-NOV 1979 |
BURMA |
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NOV-DEC 1979 |
BANGLADESH |
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JAN-FEB 1980 |
SRI LANKA |
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MAR-APR 1980 |
BURMA |
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MAY 1980 |
BANGLADESH |
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JUN-AUG 1980 |
MALAYSIA/THAILAND/INDONESIA |
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SEP-NOV 1980 |
MOZAMBIQUE |
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DEC 1980 |
KENYA |
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JAN-FEB 1981 |
OMAN AND ADEN GULFS |
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MAR 1981 |
EGYPT |
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MAR 1981 |
TUNIS |
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APR 1981 |
ALGIER |
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APR-DEC 1981 |
WEST-AFRICA |
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DEC 1981-APR 1982 |
WEST-AFRICA |
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JUN 1982 |
TANZANIA |
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AUG 1982 |
KENYA |
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SEP-OCT 1982 |
MOZAMBIQUE |
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NOV-DEC 1982 |
TANZANIA |
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FEB-MAR 1983 |
GULF OF OMAN/PAKISTAN |
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MAY-JUN 1983 |
KENYA/TANZANIA/MOZAMBIQUE/MADAGASCAR |
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AUG-SEP 1983 |
MALDIVES/PAKISTAN/IRAN |
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NOV-DEC 1983 |
GULF OF OMAN/OMAN EEZ |
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JAN-MAR 1984 |
PAKISTAN/S.YEMEN/SOMALIA/ETHIOPIA |
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APR-JUN 1984 |
OMAN/IRAN/PAKISTAN |
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AUG-SEP 1984 |
S.YEMEN/SOMALIA/OMAN |
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MAR-DEC 1985 |
CONGO/GABON |
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JAN 1985-JUN 1986 |
ANGOLA |
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AUG-DEC 1986 |
WEST-AFRICA |
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FEB-DEC 1987 |
CENTRAL-AMERICA |
