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Transferability of models to predict selection of cover by coastal cutthroat trout in small streams in western Oregon, USA

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dc.contributor.advisor Dunham, Jason B.
dc.creator Andersen, Heidi V.
dc.date.accessioned 2008-12-23T00:25:48Z
dc.date.available 2008-12-23T00:25:48Z
dc.date.copyright 2008-11-07
dc.date.issued 2008-12-23T00:25:48Z
dc.identifier.uri http://hdl.handle.net/1957/9969
dc.description Graduation date: 2009 en_US
dc.description.abstract We assessed use and selection of cover by coastal cutthroat trout (Oncorhynchus clarkii clarkii) in six headwater streams in three watersheds in western Oregon, USA during the summer low flow period from 1 August and September 30, 2007. We tagged 1037 coastal cutthroat trout (>100 mm) with passive integrated transponder (PIT) tags across all streams. Selection of cover was analyzed by comparing characteristics of locations used for concealment by relocated fish relative to characteristics of randomly available habitat that could be used for concealment. We measured habitat characteristics for 190 relocated individual fish using cover and 797 randomly points potentially available as cover. Of the latter points, only 235 of 797 were potential cover, based on characteristics of cover actually used by fish. In other words, 562 of the 797 randomly sampled points were unlikely to be used as cover by fish. Coastal cutthroat trout used substrate as cover (78%) more often than all other cover types combined (22%). Availability of different cover types was variable, but overall substrate made up 92% of available cover and the remaining 8% represented all other cover types combined. Habitat characteristics measured for both used and available cover included depth at fish location (cm), surface area of cover (m²), proximity to depth of 20 cm for fish located in < 20 cm in depth, b-axis (mm) for substrate >2 mm, and distance under substrate. Each of these habitat characteristics was different for used and available cover (Wilcoxon rank-sum p-values all < 0.0001). Analysis of selection using logistic regression models indicated that cover use was more likely with increasing depth and surface area of cover. A negative interaction effect between the influences of depth and surface area suggested fish were more likely to use cover with smaller surface areas in deeper water. We found good transferability (i.e. predictive capabilities) of the logistic regression models across streams using three different methods: "leave-one-stream-out" cross validation, Cohen's kappa statistic, and receiver operator characteristic curves. Our results suggested that characteristics of used cover were similar across six streams for coastal cutthroat trout in headwater streams. The strong and consistent influence of both depth and surface area of cover on selection of habitat by individual coastal cutthroat trout suggests these features of habitat may be critical to this species during summer low flows. en_US
dc.language.iso en_US en_US
dc.relation Explorer Site -- Oregon Explorer en_US
dc.subject cutthroat trout en_US
dc.subject habitat selection en_US
dc.subject transferability en_US
dc.subject cover en_US
dc.subject headwater streams en_US
dc.subject PIT tags en_US
dc.subject.lcsh Coastal cutthroat trout -- Oregon, Western en_US
dc.subject.lcsh Coastal cutthroat trout -- Habitat -- Oregon, Western en_US
dc.subject.lcsh Coastal cutthroat trout -- Behavior -- Oregon, Western -- Mathematical models en_US
dc.subject.lcsh Habitat selection -- Mathematical models en_US
dc.title Transferability of models to predict selection of cover by coastal cutthroat trout in small streams in western Oregon, USA en_US
dc.type Thesis en_US
dc.degree.name Master of Science (M.S.) in Fisheries Science en_US
dc.degree.level Master's en_US
dc.degree.discipline Fisheries and Wildlife en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Burnett, Kelly M.
dc.contributor.committeemember Rosenberg, Daniel K.

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