Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 242-257).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2006. / Includes bibliographical references (leaves 37-43).

No description available.

No description available.

Thesis (M.S.)--University of Wisconsin -- La Crosse, 1984. / Includes bibliographical references (leaves 56-63).

Thesis (M.S.) in Natural Resources, Fisheries--University of Wisconsin--Stevens Point, 2003. / Includes bibliographical references (leaves 93-100).

Humans domesticate nature to suit their needs. Such alterations can create trade-offs between human needs and ecosystem services. Quantification of these trade-offs is needed to domesticate nature more wisely. My thesis quantifies tradeoffs between invasive species control and the rehabilitation and protection of native fishes associated with the preservation and relocation of the dam on the Black Sturgeon River on the north shore of Lake Superior. I evaluated the trade-offs in terms of five performance measures: abundances of walleye, sea lamprey, lake sturgeon, and northern brook lamprey, and financial cost. I found that the management of the Black Sturgeon River would depend on value judgments because of the high complexity and uncertainty of the system. The analysis of the Black Sturgeon River could be an example of how to evaluate the trade-offs between invasive species control and native fish passage and be used for similar systems which share this trade-off.

Smallmouth bass (Micropterus dolomieu) have experienced substantial range expansions in northern Ontario over the past century, with adverse consequences for native salmonid predators. It is unclear how climate-induced water clarity shifts will affect interactions between native dark-adapted walleye (Sander virteus) and invading smallmouth bass in northern Ontario. This study used stable isotopes of nitrogen (15N/14N) and carbon (13C/12C) in fish muscle tissue to investigate how resource partitioning between walleye and smallmouth bass is related to water clarity in 34 small (100-200 ha) Boreal Shield lakes (ranging from 1 to 8.5 m Secchi depth, and from 3.2 to 13.1 mg/L DOC). Quantitative metrics of trophic niche dimensions (based on the size, position, and dispersion of multivariate ellipses drawn around sampled individuals in δ15N vs. δ13C biplot space) were calculated for each individual population and used to determine trophic interactions and niche overlap between sympatric walleye and smallmouth bass. Linear and multiple regressions were then used to explore potential relationships between trophic interactions and water clarity. Available habitat and fish assemblage data was also explored for potential influences on isotopic niche dimensions and trophic interactions of walleye and smallmouth bass. Total occupied niche space decreased significantly with increasing water clarity for smallmouth bass as populations occupied a narrower range of trophic levels and made greater use of pelagic resources. In contrast, walleye trophic niche dimensions did not respond significantly to water clarity. Isotopic niche overlap ranged from 0 to 65%, but no metric of trophic overlap was significantly related to water clarity. Other abiotic and biotic variables, however, did have a significant influence on the similarity between some aspects of walleye and smallmouth iv bass isotopic niche dimensions (but not interaction). Both species fed on more isotopically similar carbon sources as lakes became shallower, which may be a result of a lack of distinct littoral and limnetic habitats. Walleye and smallmouth bass niche size also became more similar with increasing DOC but this may be a result of lower prey diversity. Both species also occupied more similar average food web positions as yellow perch relative abundance increased, indicating that the exploitation of yellow perch by both species increased with perch abundance. Together with other studies that have found little evidence for an impact of smallmouth bass on walleye fitness and abundance, this research suggests that, unlike salmonid and cyprinid species, walleye may be resilient against smallmouth bass invasions regardless of water clarity conditions in oligotrophic boreal lakes.

This study has presented a comprehensive overview of the status and ecology of walleye and sauger in the Wabash River, Indiana. Populations of walleye and sauger are relatively low in numbers. Both species exhibited a trend of increased abundance with river km from the mouth of the Wabash River. Summer walleye habitat use and movements were examined in the upper Wabash River. Walleye preferred run habitat over riffle or pool habitat. Lateral position, substrate use, and mean depth appeared to be influenced by discharge. Movements were generally short and occurred within a relatively small home range of 1.7 km. The population size limits the fisheries potential for walleye and sauger in the Wabash River mainstem. The upper Wabash River supports higher abundances of these species than the middle Wabash River and may provide a focal point for future management efforts. / Department of Biology