Document Type

Article

Journal/Book Title/Conference

Transactions of the American Fisheries Society

Volume

122

Issue

5

Publisher

American Fisheries Society

Publication Date

1993

First Page

717

Last Page

730

DOI

10.1577/1548-8659(1993)122<0717:AEMOGE>2.3.CO;2

Abstract

The gastric evacuation rates of brown trout Salmo trutta (0.9–1.6 kg) feeding on fingerling rainbow trout Oncorhynchus mykiss (3.5–7.6 g) were measured in the laboratory at five temperatures (4.5, 9.0, 14.0, 19.0, and 22.5°C). Instantaneous gut evacuation rates (Re) increased exponentially with temperature (T): Re = 0.053se^0.073T, r^2 = 0.98; they varyied from 7%sh^–1 at 4.5°C to 29%sh^–1 at 22.5°C. Linear regressions described the relationship between time and qualitative measures of fish digestion, thus allowing investigators to determine how long an ingested fish would be identifiable at different temperatures. An analysis of published evacuation rates (N = 121) of 22 fish species indicated that both temperature and prey size (PS, g wet weight) significantly affected digestion rate (Re): Re = 0.049se^0.072sT– 0.060 log e^(PS) R^2 = 0.52. Predator size did not significantly affect rates of evacuation.

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