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dc.contributor.authorNeuswanger, Jason
dc.date.accessioned2014-11-10T19:11:16Z
dc.date.available2014-11-10T19:11:16Z
dc.date.issued2014-08
dc.identifier.urihttp://hdl.handle.net/11122/4691
dc.descriptionThesis (Ph.D.) University of Alaska Fairbanks, 2014.en_US
dc.description.abstractChinook salmon (Oncorhynchus tshawytscha) are critical to subsistence and commerce in the Yukon River basin, but several recent years of low abundance have forced devastating fishery closures and raised urgent questions about causes of the decline. The Chena River subpopulation in interior Alaska has experienced a decline similar to that of the broader population. To evaluate possible factors affecting Chena River Chinook salmon productivity, I analyzed both population data and the behavior of individual fish during the summer they spend as fry drift feeding in the river. Using a stereo pair of high definition video cameras, I recorded the fine-scale behavior of schools of juvenile Chinook salmon associated with woody debris along the margins of the Chena River. I developed a software program called VidSync that recorded 3-D measurements with sub-millimeter accuracy and provided a streamlined workflow for the measurement of several thousand 3-D points of behavioral data (Chapter 1). Juvenile Chinook salmon spent 91% of their foraging attempts investigating and rejecting debris rather than capturing prey, which affects their energy intake rate and makes foraging attempt rate an unreliable indicator of foraging success (Chapter 2). Even though Chinook salmon were schooling, some were highly territorial within their 3-D school configurations, and many others maintained exclusive space-use behaviors consistent with the population regulatory effects of territoriality observed in other salmonids (Chapter 3). Finally, a twenty-year population time series from the Chena River and neighboring Salcha River contained evidence for negative density dependence and a strong negative effect of sustained high summer stream discharge on productivity (Chapter 4). The observed territoriality may explain the population's density dependence, and the effect of debris on foraging efficiency represents one of many potential mechanisms behind the negative effect of high stream discharge. In combination, these findings contribute to a statistically and mechanistically plausible explanation for the recent decline in Chena River Chinook salmon. If they are, in fact, major causes of the decline (other causes cannot be ruled out), then we can be tentatively hopeful that the population may be experiencing a natural lull in abundance from which a recovery is possible.en_US
dc.description.tableofcontentsGeneral Introduction -- Chapter 1: Measuring fish and their habitats: Versatile 2-D and 3-D video techniques with user-friendly software -- Chapter 2: Mechanisms of drift-feeding behavior in juvenile Chinook salmon and the role of inedible debris in a clear-water Alaskan Stream -- Chapter 3: Territoriality within schools: dynamic competition of drift-feeding juvenile Chinook salmon in 3-dimensional space -- Chapter 4: Low productivity of Chinook salmon strongly correlates with high summer stream discharge in two Alaskan rivers in the Yukon drainage.en_US
dc.language.isoen_USen_US
dc.titleNew 3-d video methods reveal novel territorial drift-feeding behaviors that help explain environmental correlates of Chena River chinook salmon productivityen_US
dc.typeThesisen_US
dc.type.degreephden_US
dc.identifier.departmentDepartment of Biology and Wildlifeen_US
dc.contributor.chairRosenberger, Amanda E.
dc.contributor.committeeEvenson, Matthew J.
dc.contributor.committeeAdkinson, Milo D.
dc.contributor.committeeBradford, Michael J.
refterms.dateFOA2020-03-20T01:50:03Z


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