Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 57-68). Also available on the World Wide Web.

The temporal and spatial variations in the activity of cutthroat trout in a small coastal British Columbia lake (49°19'N, 122°34’W) were examined in order to determine the Impact of activity on the production of fish, and the factors controlling activity. Sonar tracking, diving, netting and tagging, rise observation, stomach content-prey distribution comparision, and echo sounding were used in the Investigation. Average activity levels were at least an order of magnitude below any published values. Energy values were correspondingly low; the maximum estimate of annual energy expenditure in activity (including routine metabolism) was 2330 kCal/kg/yr, which is well below the accepted 'rule' of field metabolism being twice the routine metabolism (3860 kCal/kg/yr). Fish behavioral problems and methodological shortcomings are considered responsible for this result. Activity over 5 min intervals was quite variable. Daily activity peaked during dawn and dusk. The level of activity decreased in late fall and early spring, and there was a shift from the littoral zones during summer. The cutthroat in the lake appear to maintain home ranges-for up to 5 months. Factors affecting activity can be broken into 3 categories: Temperature, light, and oxygen primarily determine the depth zones that are accessible to fish. Substrates such as Potamogeton beds and logs may act to concentrate fish within accessible depth zones; attraction is likely due to the higher food levels and/or increased cover found in these areas. Bottom slope, by affecting foraging efficiency in the productive littoral areas, might also affect the summer offshore distribution of fish within an accessible depth zone. It is suggested that the indirect effects of activity (specifically, the offshore movement of fish in summer) can be equally or even more important to the production of fish than is the direct use of energy for activity. higher food levels and/or increased cover found in these areas. Bottom slope, by affecting foraging efficiency in the productive littoral areas, might also affect the summer offshore distribution of fish within an accessible depth zone. It is suggested that the indirect effects of activity (specifically, the offshore movement of fish in summer) can be equally or even more important to the production of fish than is the direct use of energy for activity. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on June 30, 2008). Includes bibliographical references (p. 96-98).

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Title from PDF t.p. (viewed on June 10, 2006). Chairperson, Graduate Committee: Thomas McMahon. Includes bibliographical references (p. 52-62).

Thesis--Wisconsin. / Includes bibliographical references (leaves 12-15).

Thesis (Ph. D.)--University of Washington, 1985. / Vita. Includes bibliographical references (leaves [98]-105).

Differences in food habits and spatial distribution of sympatric Dolly Varden (Salvelinus malma) and cutthroat trout (Salmo clarki clarki) in a small coastal lake were documented by Andrusak (MS 1968). Segregation was inferred to be of the interactive type hypothesized by Nilsson (1965, 1967). The object of this study was to describe feeding behavior of individuals from these sympatric populations, and to evaluate the importance of food exploitation to the segregation process. Individual and paired fish were studied in the laboratory throughout the spring, summer and autumn. The different food habits were found to be due to a number of basic behavioral and morphological differences between the species. Dolly Varden oriented to and rested on the bottom. Cutthroat rested in the water column and were frequently surface oriented. Searching behavior differed between the species. Dolly Varden swam faster and at relatively constant rates. They sampled "mouthfuls" of substrate as they searched. Trout alternately hovered and cruised, sampling specific items. At low light intensities they were much less successful than the char at finding benthic food items. The mouth of the Dolly Varden is small and "scoop-like" compared to that of the cutthroat, and seems particularly well adapted for benthic feeding. Dolly Varden searched persistently for benthic organisms in the absence and presence of surface insects. Cutthroat rapidly switched from bottom to surface feeding if insects were presented there. The observed differences between species were fully expressed in isolated individuals. There was no evidence of the differences being magnified through interspecific competition. These differences, believed to be inherent, were considered sufficient to keep the species segregated without the involvement of competition. Segregation was concluded not to be of the interactive, type, even though the populations still retained considerable plasticity enabling them to switch diets or habitats when necessary or advantageous. The period of intense competition and food exploitation was considered to have occurred and ended during earlier stages of the coexistence. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 47-55). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 53-61). Also available on the World Wide Web.

For many native, imperiled salmonid species, the prioritization of recovery and conservation efforts hinges upon the identification of a species most limiting life stage. The early life-history stage can be a limiting life stage for fish, and given the importance of the reproductive stage to overall persistence, there is a need to better understand the spawning ecology and early life history of many salmonids. The Logan River, in northern Utah, contains one of the largest metapopulations of imperiled Bonneville cutthroat trout (BCT) throughout the Bonneville Basin. Little research has evaluated the temporal and spatial distribution of BCT spawning nor quantified their early life-history survival. In the summer of 2008, I documented the spawning ecology of BCT and quantified their early life-history survival via egg-to-fry survival field experiments in four tributaries to the Logan River. I observed considerable variability in the timing, magnitude, and duration of spawning between study streams, in part as a function of a variable, multi-peaked hydrograph. I also conducted egg-to-fry survival experiments using incubation boxes and hatchery-fertilized, eyed cutthroat embryos and installed these boxes throughout my study streams. I found that survival was extremely variable within and among my study streams. For example, the variation I observed in survival appeared to be a function of fine sediment loads. Lastly, I observed that in the Logan River the timing of greatest intensity of both stream side and in-stream anthropogenic activities (e.g., livestock grazing, horseback riding) overlaps directly with the spawning and early life stages of BCT. Using my estimates of early survival, I revised a four-stage matrix population model for BCT in order to evaluate the hypothetical effects of anthropogenic impact on rearing areas. I determined that population growth rates are sensitive to perturbation at the egg-to-fry and fry to age-1 stages, and if even a small number of redds are destroyed through habitat degradation, a high degree of immigration of reproductively mature BCT is required to maintain the near-term persistence of this population. Future conservation efforts for BCT should be prioritized to protect areas where land-use activities are high during the sensitive spawning and early life-stage periods.