Changes of acoustic target strength during juvenile perch development

摘要: Abstract Dependence of acoustic size (target strength—TS in dB) on body length juvenile perch ( Perca fluviatilis L.) was studied. Perch larvae were reared a laboratory tank from spawning to the age 89 days. Fish and TS measured during 3, 7, 15, 22, 45 days life. using Simrad 500 EY split-beam echosounder with frequency 120 kHz BioSonics Model 101 dual-beam 420 kHz down-looking, horizontal up-looking directions. Range fish 7–41 mm corresponded range −69 −53 dB. Differences between different aspects not found young larvae. ventral dorsal appears grow faster than side aspect for 15–30 mm long. With larger 40 mm, vertical reach similar values. This paper provides regressions identification acoustically detected targets. The results indicate that TS/length relationship early life stages is too general relationship.