Application of electrical conductivity for non-destructive measurement of channel catfish, Ictalurus punctatus , body composition

Abstract

A non-destructive method for determining water, protein, lipid and ash content along with lean bodymass (LBM; total body mass – total lipid mass) in live channel catfish was evaluated. This non-invasive technique involved placing the fish within a low-frequency electromagnetic field and measuring the total body electrical conductivity (TOBEC) based on the distinct electrical characteristics of body fat and fat-free tissues. The correlations between TOBEC and whole-body composition were examined using age-1+ channel catfish ranging from 44 to 175 g. Significant linear relationships between TOBEC, body weight, and total length, or combinations of these parameters, and LBM, ash, lipid, protein, and water content were found; r2 values ranged from 0.863 to 0.998. Equations for predicting body composition from TOBEC and morphometric measurements were developed. Analysis of an independent group of fish demonstrated TOBEC equations to be reliable predictors of body composition. This technique should allow successive monitoring of body composition of individual fish at different times and provide additional insight intothe body composition dynamics of channel catfish. © 1994 IFREMER-Gauthier-Villars.