A microwave energy meter to estimate energetic reserves in juvenile sturgeon

Abstract

Energetic stores can be metrics of fish health but are determined using lethal methods. Validation of non-lethal alternatives to estimate energetic stores would facilitate monitoring of wild fish of conservation concern, such as sturgeons. The Distell Fatmeter, a microwave energy meter, has been validated to estimate energetic reserves in a range of fish taxa but has not been tested on sturgeon. Therefore, Fatmeter measurements were tested as a predictor of captive hatchery-origin juvenile pallid sturgeon (fork length: 240–415 mm) energetic reserves determined by lethal proximate analysis. Fatmeter measurements combined with size and condition metrics accounted for 40 to 45% of the variation in whole-body energetic reserves, which is notably lower than reported in previous studies on other fish taxa and a modest improvement on variation explained by size and condition metrics alone in the same sturgeon population. We suggest the low variation accounted for by the Fatmeter may be a result of small body size and low whole-body lipid content and recommend follow-up studies on sturgeon larger than 415 mm in fork length.