Document Type

Thesis - Open Access

Award Date

2020

Degree Name

Master of Science (MS)

Department / School

Natural Resource Management

First Advisor

Steven R. Chipps

Second Advisor

Jonathan A. Jenks

Keywords

american mink, baci, brown trout, pit tag, predator removal, radio telemetry

Abstract

I compared movement, home range, habitat selection, and mortality among radio-tagged Brown Trout (Salmo trutta) at an American Mink (Neovison vison)-removal site, improved habitat site, and an undisturbed stream site in Rapid Creek, South Dakota. I observed high, post-surgery (> 26 days) survival rate (90%) of radio tagged Brown Trout. Average gross movement of Brown Trout was greater at the improved habitat site (127 m) compared to the mink removal (31 m) site, while average home range size (i.e., stream distance) among all three sites was not significantly different indicating strong site fidelity (125 to 200 m). Brown Trout movements were greatest in the Fall-Winter when fish selected deeper water habitats (pools and runs). No apparent mink predation occurred in the mink removal site, whereas 22% (7 of 32) of fish fates were attributed to apparent mink predation at other sites. I assessed mean weekly mink activity, along with the abundance and apparent survival of Brown Trout before (29 weeks) and after (36 weeks) predator block management efforts were implemented at the mink removal site. Mean weekly mink activity decreased in the improved habitat (-43%) and mink removal (-55%) sites after predator block management was initiated, while there was no significant decrease in mink activity at the undisturbed site. After mink removals were implemented, I observed substantially higher abundance and apparent survival of Brown Trout at the mink removal site compared to the improved habitat site, and substantially higher apparent survival in the mink removal site compared to the undisturbed stream site. There was essentially no change in Brown Trout abundance at the undisturbed site. Mink activity varied with time of year and was greatest during early Spring and late Summer, coinciding with the breeding season and juvenile dispersal period, respectively. Using radio telemetry, I evaluated the movements of mink at the improved habitat and undisturbed sites. I observed similar patterns in mink movement at the improved habitat (gross movement; 775 m) and undisturbed sites (665 m); however, home range size indicated stronger site fidelity in the improved habitat area (1,987 m) compared to the undisturbed site (4,510 m). I found that localized, mink removal efforts reduced mink activity and thus their predation on Brown Trout, resulting in lower gross movement, and greater trout abundance and apparent survival. The removal of two, adult mink from the mink removal site may have eliminated territorial boundaries and allowed mink from the improved habitat site (3.6 km upstream) to expand their home range further downstream explaining the unexpected decrease in mean weekly mink activity at that site. Smaller average home range distance in the improved habitat area allowed mink to concentrate their movements, which may be a result of the additional overwater structure that mink use to hunt prey.

Library of Congress Subject Headings

Brown trout -- South Dakota -- Rapid Creek.
Brown trout -- Effect of predation on -- South Dakota -- Rapid Creek.
American mink.
Predation (Biology)

Format

application/pdf

Number of Pages

128

Publisher

South Dakota State University

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Rights Statement

In Copyright