Presentation Type

Poster

Faculty Mentor’s Full Name

Lisa Eby

Faculty Mentor’s Department

Ecosystem and Conservation Sciences

Abstract

In western Montana, Westslope Cutthroat Trout (WCT) have become increasingly confined to small headwater tributaries. In these systems, habitat degradation and Eastern Brook Trout (EBT) invasion pose major threats to WCT. Even though movement is a well-established key process enabling fishes to access spawning, foraging, and overwintering habitats and meet their resource needs in a heterogeneous stream environment, little is known about resident WCT movement in these headwater systems. As we work to conserve these populations, describing the scales of movement and understanding how they differ among streams is useful. The objective of this project was to describe summer WCT movement in seven Western MT streams of varying habitat characteristics (and differing Eastern Brook Trout presence) to contribute to limited existing knowledge on the topic. We captured 478 WCT and 250 Eastern Brook Trout across seven different headwater streams in June 2019 and implanted PIT tags in fish >70 mm in length. From July-September 2019, all streams were mobile read using a backpack RFID antenna three separate times and fish migration/emigration was monitored in three streams with fixed RFID antenna arrays. To reduce issues associated with potential shed tags, we only consider movements greater than 2m in the analyses. Approximately 82 percent of WCT moved more than 2m over the course of the season, although fish didn’t move long distances as median movement was less than 100m within each tributary. We found no correlation between WCT movement and fish length or EBT presence. Results indicate that study streams with high pool volume possessed limited fish movement when compared to streams with lower pool volume.

Category

Life Sciences

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Westslope Cutthroat Trout summer movement in western MT headwater streams

In western Montana, Westslope Cutthroat Trout (WCT) have become increasingly confined to small headwater tributaries. In these systems, habitat degradation and Eastern Brook Trout (EBT) invasion pose major threats to WCT. Even though movement is a well-established key process enabling fishes to access spawning, foraging, and overwintering habitats and meet their resource needs in a heterogeneous stream environment, little is known about resident WCT movement in these headwater systems. As we work to conserve these populations, describing the scales of movement and understanding how they differ among streams is useful. The objective of this project was to describe summer WCT movement in seven Western MT streams of varying habitat characteristics (and differing Eastern Brook Trout presence) to contribute to limited existing knowledge on the topic. We captured 478 WCT and 250 Eastern Brook Trout across seven different headwater streams in June 2019 and implanted PIT tags in fish >70 mm in length. From July-September 2019, all streams were mobile read using a backpack RFID antenna three separate times and fish migration/emigration was monitored in three streams with fixed RFID antenna arrays. To reduce issues associated with potential shed tags, we only consider movements greater than 2m in the analyses. Approximately 82 percent of WCT moved more than 2m over the course of the season, although fish didn’t move long distances as median movement was less than 100m within each tributary. We found no correlation between WCT movement and fish length or EBT presence. Results indicate that study streams with high pool volume possessed limited fish movement when compared to streams with lower pool volume.