First Advisor

Stanley S. Hillman

Term of Graduation

Summer 2002

Date of Publication

7-18-2002

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Biology

Department

Biology

Language

English

Subjects

Rainbow trout -- Effect of temperature on -- Oregon

DOI

10.15760/etd.4037

Physical Description

1 online resource (vii, 123 pages)

Abstract

The objective of this thesis was to determine whether the redband trout (Oncorhynchus mykiss ssp.) of Oregon's inland desert basins are negatively affected by the high peak temperatures (> 20 °C) often observed in their native streams. Small (40 - 140 g) redband trout from three streams (Bridge, Rock, and Twelve-mile creeks) were collected and tested on-site for aspects of thermal physiology, including: critical swimming velocity (Ucrit), maximum metabolic rate (MO2), metabolic power, and total cost of transport (TCT) at 24 °C; routine MO2 at 14 to 2: 28 °C: and critical thermal maximum (CTM). At Bridge Creek, large (400 - 1400 g) redband trout were also tested to evaluate differences between size/age classes in thermal physiology.

The CTM was highly conserved between all groups, with an overall mean of 29.4 °C. Routine MO2 increased with temperature for all groups. and in each case increased more steeply  temperatures above 24 °C. Although routine MO2 was similar for all small trout at each temperature, large trout exhibited higher mass-adjusted routine MO2 at 24, 26, and 28 °C and higher Q 10 from 14 to 26 °C compared with small trout at Bridge Creek. Significant differences in swimming performance and/or efficiency at 24 °C were also observed between streams and size classes, but maximum MO2 and metabolic power were conserved. These data indicate that acute exposure to high temperatures may be more energetically costly for larger/older redband trout, and that variation in performance may be moderated by variation in aerobic efficiency of swimming.

In comparison with published data for salmonids at 'normal' summer temperatures, redband trout at 24 °C generally had higher routine and maximum 1\102, similar metabolic power and Ucrit, and higher total cost of transport, indicating that performance is not compromised but that higher metabolic costs are sustained at this temperature. Where published data were available for comparisons with salmonids at similarly high temperatures, no clear evidence of adaptive difference in redband trout physiology was found. Recommendations regarding thermal requirements for the management of redband trout populations are presented. and directions for future research are proposed.

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Persistent Identifier

https://archives.pdx.edu/ds/psu/44471

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