| Summary: | Thesis (M.S.) University of Alaska Fairbanks, 2022 Understanding the processes underlying dispersal propensity in animal populations is a fundamental goal of ecologists. In metapopulations of wild Pacific (Oncorhynchus spp) and Atlantic salmon (Salmo salar, hereafter collectively referred to as "salmon"), it is recognized that dispersal, or straying, exists in tandem with philopatry and provides benefits such as gene flow and colonization of new habitat. However, straying by hatchery-produced salmon into streams can negatively affect the genetic integrity and reproductive success of wild salmon populations. Straying by hatchery-origin salmon may also confound fishery management procedures around assessing wild spawner escapement, given the difficulty in identifying hatchery salmon in the field. A first step in mitigating and managing the consequences of straying by hatchery salmon is to understand where and why hatchery salmon stray. In this study, I described the relationship between the number of hatchery-origin strays received by streams and the characteristics of those streams based on the hypothesis that certain characteristics are attractive to hatchery strays. An extensive dataset documenting the number of stray hatchery-origin chum salmon (Oncorhynchus keta) that spawned in 57 streams in Southeast Alaska was produced from hundreds of field surveys conducted over a 10-year period 2008-2019. I used these data in a generalized linear mixed effects modeling framework to predict how "attractive" a given stream was to hatchery strays based on hypothesized influential stream characteristics, such as streamflow, distance and numbers of hatchery releases, and conspecific density. I found that some streams were more attractive than others to hatchery strays: 10 of 57 streams surveyed had mean observed attractiveness indices of 39 recipient strays over time (range: 12-115) in a given survey, while the remaining 47 sites only attracted two recipient strays on average (range: 0-8). Furthermore, stream ...
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