A Comparison between Two Sonic Measuring Systems for Demersal Fish

• Published in: Journal of the Fisheries Research Board of Canada
• Main Authors: Dowd, R. G., Bakken, E., Nakken, O.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1970
• Subjects: General Medicine; Lofoten; Norway
• Online Access: http://dx.doi.org/10.1139/f70-077; http://www.nrcresearchpress.com/doi/pdf/10.1139/f70-077

Two sonic methods for estimation of abundance of fish stocks, the echo integrator and the digital counter methods, were compared on single and schooling fish in the Lofoten area of Norway during March 1969. Good correlation was obtained between the two systems for both situations, but the slopes of the regressions of integrated values on the digital counter differed significantly between low and high density fish concentrations. This suggests that the two systems treated the echo information differently, but nevertheless maintained a linear relation between themselves over a wide range of counts.