Failure of Total Body Electrical Conductivity to Predict Lipid Content of Brook Trout

Abstract

We found that a noninvasive procedure that used total body electrical conductivity (TOBEC) failed to estimate lean mass and whole body lipid content of brook trout Salvelinus fontinalis. We explored two approaches using TOBEC, the inverse-regression approach, in which lipid mass is predicted from the relationship between TOBEC, and lean mass and the multiple-regression approach, in which lipid is predicted directly from TOBEC and morphological measurements. With the inverse-regression approach, TOBEC was a good estimator of lean mass but did not predict lipid mass. With the multiple-regression approach, length and mass alone explained lipid mass best; TOBEC did not add significant explanatory power. We conclude that TOBEC was not a sensitive or cost-effective tool for determining lipid content of brook trout and urge caution in its use with other fish species.