KSK6005114 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR)
KSK3046108 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR)
IAA6017901 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR)
IAA6017801 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR)
Annotation
Dependence of acoustic size (Target strength - TS in dB) on body length of juvenile perch (Perca fluviatilis L.) was studied. Perch larvae were reared in a laboratory tank from hatching to the age of 89 days. Fish length and TS were measured during 3, 7, 15, 22, 45 and 89 days of life. TS was measured using a Simrad 500 EY split-beam echosounder with the frequency 120kHz and a BioSonics Model 101 dual-beam echosounder with the frequency 420 kHz in downlooking, horizontal and uplooking directions. Range of fish body length 7-41 mm corresponded with a TS range from -69 dB to -53 dB. Differences between TS of different aspects were not found in young fish larvae. TS in ventral and dorsal aspects appears to grow faster than in the side aspect for fish 15-30 mm long. With perch larger than 40 mm, vertical and side aspects reach similar values. This paper provides regressions for the size identification of acoustically detected fish targets.
Workplace
Institute of Hydrobiology (until 2005)
Contact
Václava Lavičková, lavickova@hbu.cas.cz, Tel.: 387 775 889
