Authors' Names

Troy W. SmithFollow

Presentation Type

Oral Presentation

Category

STEM (science, technology, engineering, mathematics)

Abstract/Artist Statement

Natal Stream Characteristics Associated with Migratory Westslope Cutthroat Trout Westslope Cutthroat Trout, hereafter cutthroat, are a native trout species of conservation concern in Montana that have historically exhibited a diversity of life histories within a population. This includes migratory individuals that move from larger rivers to their natal streams to spawn, as well as resident individuals that remain in natal streams for their lifetime. Due to habitat degradation and interbreeding (or hybridizing) with nonnative Rainbow Trout, cutthroats are becoming rare in large river systems and increasingly occur as isolated resident populations in headwater systems. This loss of migratory individuals can lead to extirpation of theses isolated, local populations. Rock Creek in Western Montana is a population of conservation and of ecological interest because it has retained a population of migratory non-hybridized cutthroat. Understanding characteristics of streams that promote migratory individuals and the persistence of the migratory life history within a population would be useful to help prioritize conservation of habitat that maintains life history diversity. Based on ecological theory we hypothesized that factors such as stream habitat quality (temperature, flow, pool depth) and competition (fish density) would be associated with migratory behavior. From 2018 to 2020, we implanted 73 radio telemetry tags and tracked cutthroat movements over this time period to determine their migratory life history and where they spawned. We collected habitat and fish population data on 37 tributary streams within the Rock Creek drainage. We used a generalized linear model to evaluate the relationship between the number of migratory individuals and certain tributary characteristics. Our results show that natal stream size is related to the abundance of migratory individuals. This study is unique in that we were able to capture and track a large number of individuals over a large landscape, which is uncommon for these types of studies. By understanding the drivers behind migratory cutthroat populations, this study will directly help managers make crucial conservation decisions about protection of watersheds and guide decisions about reconnecting habitats to provide migratory pathways.

Mentor Name

Lisa Eby

GradCon_Talk_Smith.mp4 (55163 kB)
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Natal Stream Characteristics Associated with Migratory Westslope Cutthroat Trout

Natal Stream Characteristics Associated with Migratory Westslope Cutthroat Trout Westslope Cutthroat Trout, hereafter cutthroat, are a native trout species of conservation concern in Montana that have historically exhibited a diversity of life histories within a population. This includes migratory individuals that move from larger rivers to their natal streams to spawn, as well as resident individuals that remain in natal streams for their lifetime. Due to habitat degradation and interbreeding (or hybridizing) with nonnative Rainbow Trout, cutthroats are becoming rare in large river systems and increasingly occur as isolated resident populations in headwater systems. This loss of migratory individuals can lead to extirpation of theses isolated, local populations. Rock Creek in Western Montana is a population of conservation and of ecological interest because it has retained a population of migratory non-hybridized cutthroat. Understanding characteristics of streams that promote migratory individuals and the persistence of the migratory life history within a population would be useful to help prioritize conservation of habitat that maintains life history diversity. Based on ecological theory we hypothesized that factors such as stream habitat quality (temperature, flow, pool depth) and competition (fish density) would be associated with migratory behavior. From 2018 to 2020, we implanted 73 radio telemetry tags and tracked cutthroat movements over this time period to determine their migratory life history and where they spawned. We collected habitat and fish population data on 37 tributary streams within the Rock Creek drainage. We used a generalized linear model to evaluate the relationship between the number of migratory individuals and certain tributary characteristics. Our results show that natal stream size is related to the abundance of migratory individuals. This study is unique in that we were able to capture and track a large number of individuals over a large landscape, which is uncommon for these types of studies. By understanding the drivers behind migratory cutthroat populations, this study will directly help managers make crucial conservation decisions about protection of watersheds and guide decisions about reconnecting habitats to provide migratory pathways.