The object of this study was to test the hypothesis that prey abundance in large part regulates dispersion, territory
size and aggressive behavior of young rainbow trout during the stream rearing phase of their life history.
In laboratory test channels, where age 0+ fry were introduced
into channels receiving three different amounts of prey and permitted to emigrate voluntarily, density of fry remained
highest at the highest prey level. Also, the distribution
of fry was positively associated with a gradient in prey abundance. Both territory size and frequency of aggressive encounter varied inversely with prey level; the higher the prey level, the smaller the territory and the lower the frequency of aggressive encounter. Emigration from the test channels was neither as rapid nor as marked when prey level was abruptly reduced,
compared to when fry were initially introduced to the different prey levels. However, frequency of aggressive encounter
significantly increased when the prey level was decreased
and significantly decreased when the prey was increased.
In Loon Outlet Creek, the abundance of prey was positively
associated with summer fish biomass in one study section, while a positive association was not apparent for a second study section. The second, located closer to Loon Lake, on the average tended to have throughout the summer a higher fish biomass and higher prey density. In addition, the spring lakeward migration
of juvenile rainbow trout was negatively correlated with prey density and positively correlated with temperature.
It is suggested that in the natural stream habitat, the density of fry and juvenile rainbow trout is strongly influenced
by prey density especially when associated with the metabolic effects of temperature and fish size. / Science, Faculty of / Zoology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/33309 |
| Date | January 1972 |
| Creators | Slaney, Pat A. |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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