Target Strength of encaged Atlantic redfish (Sebastes spp.)

• Published in: ICES Journal of Marine Science
• Main Authors: Gauthier, Stéphane, Rose, George A.
• Format: Text
• Language: English
• Published: Oxford University Press 2001
• Subjects: Regular Articles; Atlantic redfish
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/58/3/562; https://doi.org/10.1006/jmsc.2001.1066

Redfish ( Sebastes spp.) were caught at sea with feather hooks, kept alive in sea cages for >12 hours at 30 m depth, then transferred to cages at 10 m depth for another 12 h. Most fish survived this procedure in excellent condition. A total of 16 fish of length 24.5–30 cm were placed one at a time in an acoustically inert monofilament cage where target strength (TS) was measured for two hours using a 38 kHz split-beam echo-sounder. An underwater video camera enabled continuous monitoring of fish and cage. The best fit length based regression obtained from these data was TS=19 log [length (cm)]−66.6, in the standard format: TS=20 log [length (cm)]−68.1 (r2=0.18). TS varied by less than 4 dB over a range of tilt angles from −50° to 70° off dorsal aspect.