ACOUSTIC INSTRUMENTS
Two SIMRAD scientific echo sounders, 38 and 120 kHz, were used during the survey for estimation of fish density. In addition an ES 400 split beam sounder was used.
|
|
INSTRUMENT SETTINGS |
||
|
|
EK 400/38 |
EK 400/120 |
ES 400 |
|
Range |
0-100 or 0-250 |
0-100 |
0-25 to 0-250 |
|
Transm. |
High (5000 W NOM) |
High (1250 W NOM) |
EK/ES adapter |
|
Bandwidth |
3.3 kHz |
3.3 kHz |
3.5 kHz |
|
Pulselength |
1 ms |
1 ms |
1 ms |
|
TVG |
20 log R |
20 log R |
40 log R |
|
Attenuator |
20 dB |
0 |
Fixed |
|
Rec. gain |
7 |
5 |
|
|
Transducer |
8° × 8° ceramic or split beam |
Ceramic 10 cm circular |
Split beam 10° |
|
|
|
Presentation mode: Compensated |
|
EK 400/120 was coupled to the other QM integrator. Gain 10 dB × 10. Threshold 0.
ES 400 was connected to an Epson printer for hardcopy of the size distribution diagram (histogram).
Calibration on standard copper sphere. (Porto Alexandre 10.08.1985).
EK 400/38: SL + VR = 140.8 dB (Transd. 8° ×
8°)
EK 400/38-ES: SL + VR = 137.3 dB (Split beam
transm.)
Sonar
An ST sonar was used to detect fish schools close to the surface. Recorder range 0-250 m.
Hydrography
Temperature, salinity and oxygen content was 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 thermograph.
Fishing gear
|
Bottom trawl: |
High opening shrimp and fish trawl with rubber bobbins gear,
headline 31 m, headline height during trawling abt 6m. |
|
Pelagic trawls: |
Type “Harstadtrawl”, width abt 30 m, vertical
opening 14-16 m; Type modified “Bastrawl”, width about 25 m, vertical
opening abt 25 m; all trawls with fine meshed inner lining in cod
ends. |
