In situ measurements of capelin (Mallotus villosus) target strength in the North Pacific Ocean

• Published in: ICES Journal of Marine Science
• Main Authors: Guttormsen, Michael A., Wilson, Christopher D.
• Format: Text
• Language: English
• Published: Oxford University Press 2009
• Subjects: Articles; Barents Sea; Gulf of Alaska; Pacific; Kodiak; Alaska
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/66/2/258; https://doi.org/10.1093/icesjms/fsn205

<qd> Guttormsen, M. A. and Wilson, C. D. 2009. In situ measurements of capelin ( Mallotus villosus ) target strength in the North Pacific Ocean. – ICES Journal of Marine Science, 66: 258–263. </qd> In situ measurements of capelin ( Mallotus villosus ) target strength (TS) were collected during summer 2001–2003 near Kodiak Island in the Gulf of Alaska, using a calibrated EK500 echosounder with 38 and 120 kHz split-beam transducers. Targets were detected over dispersed, night-time aggregations using standard acoustic methods, then filtered using a quality-control algorithm to reject invalid targets. The 38 kHz-based, fitted model estimate was TS = 20 log 10 L − 70.3 ( r 2 = 0.30), where L is total length of fish. Compared with other studies, the TS-fitted model at 38 kHz was similar to that calculated from swimbladder morphology measurements from St Lawrence estuary capelin (TS = 20 log 10 L − 69.3), but resulted in greater estimates than models based on in situ measurements of capelin TS in the Barents Sea (TS = 19.1 log 10 L −74.0) and northern Atlantic Ocean (TS = 20 log 10 L − 73.1). The large intraspecific variability exhibited in the fitted TS – L models for this species suggests the use of TS measurements from the geographic region where the data were collected.