Lake trout populations were extirpated from the lower four Great Lakes by 1960 and from Lake Champlain by 1900. The decline of lake trout populations fueled a wave of restoration-based research that spanned the Great Lakes and filled in many of the gaps in our knowledge of lake trout behavior and ecology. However, remarkably little is known about lake trout spawning behavior, even less about sex-specific differences in spawning site use. Lake trout use specific spawning sites, and may return to the same site year after year. More males are caught on spawning sites than females and are present at spawning sites earlier in the spawning season. The focus of this project is to describe the spawning movements of male and female lake trout within and among spawning seasons and spawning sites. I used acoustic telemetry in Lake Champlain to look at specific questions of spawning site fidelity and whether or not there were differences in male and female movements. I hypothesized that males show site fidelity and remain at a preferred site during the spawning season, whereas females 'sample' multiple spawning reefs to maximize their reproductive success. I established an acoustic telemetry array of ten acoustic receivers placed over eight spawning sites and implanted acoustic transmitters (tags) in 44 male and 48 female lake trout over two years. During two spawning seasons, males spent more time on spawning sites than females. Both male and female lake trout that were active on monitored sites during the spawning season selected a single preferred site. There was no difference in the number of sites visited by males and females. Of the lake trout detected during both spawning seasons, most returned to their capture site in the subsequent spawning season, showing evidence of site fidelity. I also developed a binomial rolling residence test (BRR test) to improve the current method of assessing the duration of a fish's residence at a single receiver. I measured daily detection probabilities (DP) at a given distance from a receiver site. The BRR test evaluates a tag's residence every minute by moving a one-hour time window centered on time t across the duration of the data. The daily DPs are incorporated into a binomial test of the null hypothesis that a fish is not within x meters of the receiver at time t. I performed a 48-hour stationary residence test using two onsite tags and two offsite tags and compared the performance of the BRR test to three residence assessment methods found in the literature. The results showed that the BRR test performs better than all of the time-threshold residency evaluations in our 48-hour stationary residence test. We suggest that this method has the potential to advance the field of telemetry by improving the interpretation of telemetry data.

Thesis (Ph. D.)--University of Wisconsin, Madison, 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references. Also available via World Wide Web.

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (leaves 135-150).

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2002. / Includes bibliographical references (leaves 41-52).

Thesis (Ph. D.)--University of Wisconsin, Madison, 2001. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Any method used in aging fish must fulfill certain requirements to be satisfactory. If the method is inaccurate, naturally little reliance can be placed upon its use. If considerable study of the method and much practice are required before accurate readings can be obtained, the method will not come into widespread us ~. The requirements of an aging method, then are that . it must be accurate and comparatively easy. The scale method for aging lake trout (Salvelinus namaycush Walbaum) unfortunately does not fulfill these requirements.

The long-toed salamander (Ambystoma macrodactylum) is the top vertebrate predator in fishless high-elevation lakes in North Cascades National Park Service Complex (NOCA), Washington. The purpose of this research was to determine the effects of physico-chemical factors and introduced trout on abundance and behavior of A. macrodactylum larvae. Although high-elevation lakes in NOCA were naturally fishless, trout were stocked in many lakes during this century to provide recreational angling opportunity. Twenty fishless lakes and 25 lakes with fish were sampled from 1990 to 1994. Larval salamander density and behavior were assessed by snorkeling lake perimeters and searching through nearshore substrate material and aquatic vegetation. In fishless lakes, larval salamander densities were positively related to total Kjeldahl-N concentration (TKN) and negatively related to lake elevation. Based on analysis of salamander stomach contents, crustacean zooplankton, especially cladocerans, were important food resources for larval A. macrodactylum. Total crustacean zooplankton, as well as cladoceran densities, were positively related to TKN concentration, suggesting that increased zooplankton food resources contributed to increased densities of A. macrodactylum. The effects of fish introductions on larval salamander densities depended on TKN concentration and whether or not trout had established reproducing populations. Mean larval salamander densities for fishless lakes with TKN<0.05 mg/l, generated from a linear regression equation with TKN and lake elevation as independent variables, were not significantly different from mean larval densities in lakes with either reproducing trout or in lakes with non-reproducing trout. However, in fishless lakes with TKN���0.05 mg/l, mean larval densities were significantly higher than in lakes with reproducing fish where trout reached high densities. In fishless lakes with TKN���0.095 mg/l, mean larval densities were significantly higher than in lakes with non-reproducing fish where trout fry were periodically stocked at low densities. Reduced larval salamander densities in lakes with trout likely was a consequence of trout predation. Although most larvae were associated with boulder, cobble, and woody debris substrates in nearshore areas of NOCA lakes, differences in the proportion of larvae hidden in benthic substrates between lakes with fish and without fish were not statistically significant. / Graduation date: 1997

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2004. / Includes bibliographical references (leaves 93-104).

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on June 24, 2009). Includes bibliographical references.