Semester

Spring

Date of Graduation

2004

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Kyle J. Hartman.

Abstract

Three aspects of a bioenergetics model were examined for brook trout (Salvelinus fontinalis) in the laboratory: (1) refinement of the metabolism parameter estimations, (2) calculation of activity rates and (3) subsequent validation of the brook trout model. An integral part of bioenergetics modeling is the initial inputs of predator and prey energy density from body composition estimations. We present bioelectrical impedance analysis (BIA) as a means of rapidly estimating body composition in fish and then adjusted variables that may affect these predictions. We also used this tool and applied it to a compensatory growth study. Brook trout (Salvelinus fontinalis) were randomly split into 3 groups (N = 8) with each group having a different feeding regime (starved, compensatory or ad libitum). Changes in weight, gross growth efficiency, and body composition were measured repeatedly on individual fish using standard laboratory measures as well as bioelectrical impedance analysis (BIA) to determine if (1) compensatory growth occurred and (2) if the weight changes were energetic.;In 31 day bioenergetics experiments, final weights were underestimated by 4.5% (+/-11.06%, 95% confidence limits) and consumption was overestimated by 8.3% (+/-16.42%, 95% confidence limits). Bioelectrical impedance analysis models built with brook trout (Salvelinus fontinalis) were linear with strong validation group correlations (R2 > 0.86) for water, protein, fat and fat-free and dry weights. Temperature affected predicted estimates of total body water, dry weight and total weight linearly, but when data was normalized by weight, the temperature term was effectively canceled out. Gut-fill did not effect BIA predictions of any body composition parameter estimate while electrode placement did. Bioelectrical impedance analysis and standard compositional analysis determined that weight gains were energetic due to increases in protein, dry mass and fat, and not due to non-energetic gains (water). Furthermore, BIA found no significant differences in compositional changes between the treatment and control groups throughout the experiment.

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