Does Bioelectrical Impedance Analysis Accurately Estimate the Physiological Condition of Threatened and Endangered Desert Fish Species?

Abstract

Bioelectrical impedance analysis (BIA) is a nonlethal tool with which to estimate the physiological condition of animals that has potential value in research on endangered species. However, the effectiveness of BIA varies by species, the methodology continues to be refined, and incidental mortality rates are unknown. Under laboratory conditions we tested the value of using BIA in addition to morphological measurements such as total length and wet mass to estimate proximate composition (lipid, protein, ash, water, dry mass, energy density) in the endangered Humpback Chub Gila cypha and Bonytail G. elegans and the species of concern Roundtail Chub G. robusta and conducted separate trials to estimate the mortality rates of these sensitive species. Although Humpback and Roundtail Chub exhibited no or low mortality in response to taking BIA measurements versus handling for length and wet‐mass measurements, Bonytails exhibited 14% and 47% mortality in the BIA and handling experiments, respectively, indicating that survival following stress is species specific. Derived BIA measurements were included in the best models for most proximate components; however, the added value of BIA as a predictor was marginal except in the absence of accurate wet‐mass data. Bioelectrical impedance analysis improved the R2 of the best percentage‐based models by no more than 4% relative to models based on morphology. Simulated field conditions indicated that BIA models became increasingly better than morphometric models at estimating proximate composition as the observation error around wet‐mass measurements increased. However, since the overall proportion of variance explained by percentage‐based models was low and BIA was mostly a redundant predictor, we caution against the use of BIA in field applications for these sensitive fish species. Received November 7, 2016; accepted March 1, 2017 Published online July 5, 2017

Análisis de impedancia bioeléctrica (AIB) en la producción animal. Revisión

“…On the other hand, it was observed (49) weak and non-significant correlations among PA, Rs and Xc and the components of body composition, reporting that the reason for the weak correlation is that the methodology of BIA was not able to detect alterations in body composition of fish. This fact corroborates the results of other authors (50) , in which the morphological measures estimated by BIA in fish that face threat of extinction in inhabiting deserted regions were redundant, demanding caution in the field evaluation, as it presents great sensitivity.…”

Energetic Status of Alaskan Chinook Salmon: Interpopulation Comparisons and Predictive Modeling Using Bioelectrical Impedance Analysis

“…In contrast, Dibble et al. () found that the addition of BIA values that were taken on juvenile Humpback Gila cypha , Bonytail G. elegans , and Roundtail G. robusta chub into models with length and weight did not greatly increase the coefficient of determination values. Predictive body composition models that use BIA may differ in their utility based on what species is being studied.…”

Utility of Condition Indices as Predictors of Lipid Content in Slimy Sculpin (Cottus cognatus)

“…Nevertheless, we believe such morphometric indices are sufficient for predicting fat content in C. cognatus to a degree that likely suits the needs of most researchers. Although newer, sometimes promising, non-lethal methods for assessing fat content in fish have emerged [48,57,58], their apparent lack of adoption outside of studies examining their efficacy suggests that traditional methods are not going away anytime soon.…”