Applying an alternative method of echo-integration

• Published in: ICES Journal of Marine Science
• Main Author: Aksland, Magnar
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2006
• Subjects: Ecology; Aquatic Science; Ecology, Evolution, Behavior and Systematics; Oceanography; Arctic; Arctic cod
• Online Access: http://dx.doi.org/10.1016/j.icesjms.2006.03.027; http://academic.oup.com/icesjms/article-pdf/63/8/1438/29125615/63-8-1438.pdf

Abstract Estimators of mean Echo Value Constant (the ratio between echo abundance and the number of fish) in an alternative echo-integrating method were tried with the SIMRAD EK 60 split-beam echosounder. The mean fish-density estimates of NE Arctic cod were compared with corresponding estimates by the classical echo-integration method; the two methods gave similar results. The alternative method uses integrated single-fish echoes, and a new algorithm to extract and integrate single-target echoes is introduced and used. This algorithm uses echo shape and angle stability, not echo amplitude, to test for the presence of single-target echoes. Apparent single-target echoes with a dynamic range of 60 dB in integrated echo intensity were extracted.