A Target Strength and Length Relationship for Striped Bass and White Perch

Abstract

Abstract For hydroacoustic studies in which estimation of fish size and absolute abundance is desirable, researchers must either develop a relationship between target strength and fish length or borrow one from the literature. The purpose of this study was to provide a relationship between target strength and total length for two economically and ecologically important sympatric species: striped bass Morone saxatilis and white perch M. americana . We measured the dorsal aspect target strength of 12 white perch and 22 striped bass with a 120‐kHz split‐beam hydroacoustic system. The calculated target strength (TS (decibels)) to length ( L cm (cm)) relationships were as follows: white perch TS = 26.48 log 10 L cm − 69.45 ( r 2 = 0.81, P < 0.001); striped bass TS = 15.37 log 10 L cm − 56.26 ( r 2 = 0.80, P < 0.001); and a combined model TS = 15.613 log 10 L cm − 56.47 ( r 2 = 0.82, P < 0.001). Each of these models differs substantially from the equations of Love (1971) and Foote (1987), which are commonly used in acoustic studies when the actualrelationships are lacking.