Presentation Type

Poster

Faculty Mentor’s Full Name

Lisa Eby

Faculty Mentor’s Department

College of Forestry

Abstract

Fluvial Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi) occupy a variety of river habitats over their life, moving long distances in order to complete their life history. Despite being iteroparous, individual Westslope Cutthroat Trout have high mortality associate with spawning and may skip spawning some years. We hypothesized that initial body condition at tagging is positively related to probability of spawning, migration distance, and post-spawning mortality. Additionally, we expect distance moved upstream may explain variation in post-spawning survival. We used radio telemetry to track movements of 70 non-hybridized Westslope Cutthroat Trout greater than 350mm in Rock Creek, Montana from 2018 to 2019. Sixty tagged individuals moved into tributaries during spawning season across both years and migrated up river between 0.2 km and 69 km to reach putative spawning sites. We observed 34 mortalities during and after the spawning season. We explored whether probability of spawning and post-spawning mortality was related to relative condition, tagging location in the drainage (low, middle, high), and upstream distance using a generalized linear model. Contrary to our expectations, initial results suggest that individuals in poorer condition were more likely to spawn.

Category

Life Sciences

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Does Relative Condition Predict Probability of Spawning and Post-Spawning Mortality for a Migratory Inland Trout?

Fluvial Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi) occupy a variety of river habitats over their life, moving long distances in order to complete their life history. Despite being iteroparous, individual Westslope Cutthroat Trout have high mortality associate with spawning and may skip spawning some years. We hypothesized that initial body condition at tagging is positively related to probability of spawning, migration distance, and post-spawning mortality. Additionally, we expect distance moved upstream may explain variation in post-spawning survival. We used radio telemetry to track movements of 70 non-hybridized Westslope Cutthroat Trout greater than 350mm in Rock Creek, Montana from 2018 to 2019. Sixty tagged individuals moved into tributaries during spawning season across both years and migrated up river between 0.2 km and 69 km to reach putative spawning sites. We observed 34 mortalities during and after the spawning season. We explored whether probability of spawning and post-spawning mortality was related to relative condition, tagging location in the drainage (low, middle, high), and upstream distance using a generalized linear model. Contrary to our expectations, initial results suggest that individuals in poorer condition were more likely to spawn.