An Investigation into the Efficiency of Observers to Visually Detect Adult Salmon Spawning in the Prairie Creek Watershed, Humboldt County, California
Poxon B. 2012. An Investigation into the Efficiency of Observers to Visually Detect Adult Salmon Spawning in the Prairie Creek Watershed, Humboldt County, California. Humboldt State University
Abstract: "I estimated the observer efficiency of spawning surveyors conducting foot surveys for live coho and Chinook salmon in Prairie Creek, Humboldt County, California, during the 2007-2008 spawning season, and in Prairie Creek and its main tributary, Lost Man Creek, during the 2008-2009 spawning season. A dual-mark recapture design was utilized whereby adult salmon caught at weirs below the spawning grounds were tagged with both passive integrated transponder (PIT) tags and externally-visible Peterson disc tags. An array of in-stream PIT interrogation antennae was used to monitor movement of tagged individuals into and out of survey reaches. Individuals that died within survey reaches, and whose exact date of mortality was unknown, were removed from the pool of observable tagged individuals through a process that involved estimating a range ofprobable dates of mortality from confidence intervals constructed around survey life estimates; the process produced two counts of tagged fish available to be observed – one based on removing individuals at the beginning of the estimated range of mortality, and one based on removing them at the end of the range. Survey life of tagged individuals was estimated as a linear function of date of arrival at the weir, condition upon arriving at the weir, and sex."
- Type
- Academic
- Authors
- Poxon, Brian
- Date of Issue
- 2012-06
- Publisher
- Humboldt State University
- Units
- REDW
- Keywords
- Chinook salmon, Coho salmon, fish studies, mortality, Prairie Creek Watershed, Salmon spawning, spawning habitat, stream survey, thesis