Environmental Factors Associated With Long-Term Trends of Mountain Sucker Populations in the Black Hills, and and Assessment of Their Thermal Tolerance

Addressing the global loss of biodiversity is the penultimate challenge for conservation biology. In western North America, the decline of native fishes is welldocumented and resulted from burgeoning water resource development, habitat alteration, introduction of non-indigenous fishes, and riverscape changes resulting from impoundment of large river systems. Understanding population trends and addressing the causative factors involved in species declines is critical to recovery and management actions. Mountain sucker Catostomus platyrhynchus is a stream fish native to the Intermountain Region of western North America, and populations in the Black Hills of South Dakota represent the easternmost range of the species. Recent stream fishery surveys raised concerns about the status of mountain sucker populations in South Dakota. In addition, little information exists on the basic ecology of the species, which precludes informed management and conservation. The objectives of this study were to 1) document the current (2008-2010) distribution and abundance of mountain sucker in South Dakota for comparison with historical data, 2) evaluate the potential influence of physical and biological factors on the abundance and distribution of mountain sucker, and 3) assess their thermal tolerance. I analyzed stream fisheries survey data collected between 1960 and 2010 and found that mountain sucker density generally declined at three nested spatial scales: sample reach, stream, and watershed. At 14 sample reaches and two streams mountain sucker appear extirpated, whereas they persisted at densities ranging from 0.002-0.7 fish m-2 in 12 streams and eight watersheds. In 2008-2010, populations exceeding densities of 0.01 fish m-2 persisted only in Whitewood, Elk, Boxelder, and Bear Butte Creeks, and Rapid Creek and its tributaries above Pactola Reservoir, and mountain sucker appear to have been extirpated from all but one sample reach in the southern Black Hills. To explain the distribution of mountain sucker, I modeled mountain sucker presence and density as functions of geomorphic, sample reach habitat, and fish assemblage variables. Candidate models were evaluated for relative support using an information theoretic approach. Mountain sucker presence was best predicted by a combination of sample reach habitat, geomorphic, and fish assemblage variables, whereas trout density greater than 0.15 fish m-2 was associated with absence of mountain sucker. In sample reaches with mountain sucker, their density was positively associated with periphyton coverage, a food resource. Mountain sucker thermal tolerance was assessed using the lethal thermal maxima (LTM) procedure, a standard measure of thermal tolerance that is easily compared across species. The LTM of mountain sucker are not currently thermally limited in the Black Hills, but may lose suitable habitat as climate change persists. This study documents the decline of a native fish in the Black Hills of South Dakota, and a comprehensive ecosystem management approach could mitigate further loss of mountain sucker. Furthermore, the results of this study can be used to prioritize conservation areas for mountain sucker and aid in the understanding of mountain sucker ecology across their range.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - University Access Only

Discipline thesis:degree_discipline

Wildlife and Fisheries Science

Year

2011

Author dc:creator

• Schultz, Luke D.

Contributors dc:contributor

• Katie Bertrand

• mountain suckers
• population
• black hills
• environmental factors
• Natural Resources and Conservation

Statement dc:rights

• Copyright © 2011 Luke D. Schltz. All rights reserved.

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/398

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-1398