Acoustic instruments
Two SIMRAD scientific echo sounders, EK 400/38 kHz and EK 400/120
kHz were used during the survey for estimation of fish density. The EK 400/38 was coupled to a digital integrator QD as well as to an analog integrator QM. The details of the instrument settings used are as follows:
|
|
EK 400/38 |
EK 400/120 |
|
|
|
|
|
Range |
0-100 or 0-250 |
0-100 |
|
Transmitter High |
(5000 W Nom) |
High (1250 W Nom) |
|
Bandwith |
3.3 kHz |
3.3 kHz |
|
Pulselength |
0.5 ms |
1 ms |
|
TVG |
20 log R |
20 log R |
|
Attenuator |
20 dB |
0 |
|
Rec. gain |
7 |
5 |
|
transducer |
8 × 8 ceramic |
Ceramic 10 cm |
QM settings: Gain 20 dB x 10. Threshold 7
A calibration experiment using standard copper spheres performed in Baia dos Tigres 17/2/89 gave the following results: 30 × 30 transducer, SL+VR 141.2, instr. constants 1 ms 1.11, 0.5 msec 2.49. ES transducer: SL+VR 135.67 instr. constant 3.46.
Hydrography
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 ml 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 ml sweeps, estimated headline high 6 m and distance between wings during towing 18-20 m.
Pelagic trawl: Type “Harstadtrawl”, width about 30 m, vertical opening 10 - 15 m. Cod ends of trawls with fine meshed inner lining.
