Acoustic target strength of capelin in Newfoundland waters

• Published in: ICES Journal of Marine Science
• Main Author: Rose, G. A.
• Format: Text
• Language: English
• Published: Oxford University Press 1998
• Subjects: Articles; Newfoundland
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/55/5/918; https://doi.org/10.1006/jmsc.1998.0358

Acoustic target strengths (TS α ) of dispersed capelin ( Mallotus villosus ) were assessed in situ in six experiments conducted in June from 1992 to 1996 in Newfoundland waters. Calibrated dual-beam (120, 49, and 38 kHz) and split-beam (38 kHz) echo-sounders were used. A general linear model indicated that method (dual- or split-beam), fish density, and time of day relative to light conditions had no effect on TS α (p's>0.05). TS α at 120 kHz was 1 dB less than at 38 and 49 kHz (p<0.05). Capelin length and weight were the major determinants of TS α (p's<0.05). A length based model for 38 and 49 kHz was TS α =20 Log L−73.1 (−73.8 to −72.4; R2=0.69). However, fish in better condition had lower TS α independent of length. A model including the effects of length and weight was TS α =68.6 log L (cm)−15.2 log W (kg)−157.3 (R2=0.80). The effect of condition was greater on TS α assessed by weight: TS α kg−1=69.7 log L−25.5 log W (kg)−159.0 (R2=0.71; p's<0.05). These results are compared to previous work on TS α of capelin and similar species.