Semester

Spring

Date of Graduation

2012

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Kyle J. Hartman

Committee Co-Chair

Patricia M. Mazik

Committee Member

Kenneth J. Semmens

Abstract

This thesis examines how critical thermal maxima (CTM) differs between different strains of rainbow trout (Oncorhynchus mykiss) and explores the relationship between thermal tolerance and consumption, conversion efficiency, and growth rates at elevated temperatures. This thesis is comprised of three chapters; (1) an introduction and literature review on studies of temperature tolerance and growth in salmonids, (2) an experimental study investigating the CTM of three different strains of rainbow trout, and (3) an experimental study investigating the correlation between thermal tolerance and consumption, food conversion efficiency (FCE) and growth at elevated temperatures. For the first experimental study, we quantified the CTM of the Kamloop, Wytheville and Case Western strains of rainbow trout. The Case Western strain was of particular interest to us because it was thought to possess a higher thermal tolerance than other common strains of trout. We found that there were significant differences between the CTMs of the three strains and that the Case Western stain did have a higher thermal tolerance than the Kamloop and Wytheville strains (Mann-Whitney U; p < 0.003). We also found a significant positive correlation between CTM and condition factor (linear regression; p < 0.001). In the second study, we determined consumption, FCE, and growth rates at temperatures of 20 and 22°C for individuals whose CTMs had previously been determined. We found that there were significant differences between the consumption, FCE, and growth rates of the three strains at both temperatures (Two-way ANOVA; p < 0.001). In general, the Case Western strain consumed, converted less efficiently, and grew less than the other two strains at both temperatures. We also found no significant correlations between individual CTM and consumption, FCE, or growth at either temperature. There was a slight trend in these correlations however. As individual CTM increased, consumption, FCE, and growth rates tended to decrease. This may indicate some tradeoff between the ability to survive and grow at these stressful temperatures.

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