Detailed in situ target strength measurements of 0-group cod
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http://hdl.handle.net/11250/105249Utgivelsesdato
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Target strength measurements in situ of cod fry have been made using 38 and 120 kHz split
beam echo sounders. Two data sets are sampled in essentially pure, evenly sized, cod
concentrations, one in a Ullsfjord, Northern Norway, and the other one in Parisvatnet, a closed
270.000 m3 saltwater basin used for production of cod fry. The average length of the two cod
populations were 5.1 and 3.1 cm, respectively. The target strengths measured are significantly
lower than the values obtained if extrapolating the target strength to length relation used for
larger cod towards small fish. The target strength measured at 120kHz is lower than at 38
kHz. Details on measurement procedures, biology and analysis are reported.