Acoustic instruments
Simrad sounders coupled to QM integrators were used for estimating fish density:
EK 38 KHz: Basic range 0 - 100m + 100m; Transmitter Ext 2.5 kw; Bandwidth and pulse length 3 KHz, 0.6 ms; TVG and GAIN 20 log R-20 dB;Hydrography
Recorder gain 7; Transducer ceramic 9 × 8 degr. square
QM integrator: Gain 20 dB × 10, Threshold 0.8
SL + VR= 137.9 dB (Calibration 22 Nov 1982 on standard sphere)EK 400/120 KHz (2-14 Mar): Basic range 0-100 m; Transmitter High, Bandwidth and pulse length 3.3 KHz, 1.0 ms; TVG and GAIN 20 log R-0 dB
Recorder gain 4; Transducer ceramic 10 degr. circular
QM integrator: Gain 10 × 10 threshold 0
SL + VR = 112.2 dB (Calibration 31 Aug 1982 on standard sphere)EK 120 KHz (14-19 Mar): Basic range 0-100m; Transmitter 1/1, Bandwidth and pulse length 3 KHz, 0,6 ms; TVG and GAIN 20 log R-0 dB
Recorder gain 2; Transducer ceramic 10 degr. circular.
QM integrator: Gain 10dB × 10, threshold 0.8
SL + VR = 115.2 dB (Calibration 31 Aug. 1982 on standard sphere)
Temperature, salinity and oxygen content was sampled at standard depths with Nansen bottles. Oxygen was measured with Winkler method and salinity determined with inductive salinometer. Surface temperature was recorded at 4 m depth with thermograph.
Fishing gear
Bottom trawl: High opening shrimp and fish trawl with rubber bobbins gear, headline 31 m, height during trawling abt 6 m. Pelagic trawls: Type “Harstadtrawl”, meshsize codend 21 mm. width abt 30 m, vertical opening abt 15 m; Type modified “krilltrawl” width abt 50 m, vertical opening abt 30 m, codend meshsize 9 mm.
