Department of Fish, Wildlife, and Conservation Biology
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These digital collections include theses, dissertations, faculty publications, student publications, and datasets from the Department of Fish, Wildlife, and Conservation Biology. Due to departmental name changes, materials from the following historical departments are also included here: Fishery; Fishery and Wildlife Biology; Wildlife Biology.
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Browsing Department of Fish, Wildlife, and Conservation Biology by Subject "aquatic sciences"
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Item Open Access Cold summer stream temperatures reduce recruitment of native cutthroat trout populations(Colorado State University. Libraries, 2007) Coleman, Mark Anthony, author; Fausch, Kurt D., advisorTranslocation is a key strategy for conserving subspecies of native cutthroat trout Oncorhynchus clarkii, which have declined markedly throughout their native ranges in North America. Previous research showed that translocation success in high-elevation southern Rocky Mountain streams was more likely in warmer streams, and suggested that cold temperatures could limit juvenile trout recruitment and explain translocation failures. However, the effects of cold temperature on recruitment had not been previously investigated. I studied these effects using an integrated laboratory and field approach. In the lab, age-0 Colorado River cutthroat trout O. c. pleuriticus were subjected to one of three natural temperature regimes during two years, which averaged 7°C, 8.5°C and 10.0°C during the warmest summer month. From hatching to swimup, mean survival was high during both years, ranging from 97% (warm regime) to 85% (cold). After swimup, warm regime fry had much greater survival and grew more than 60% larger, on average, than cold regime fry by the onset of winter in the 2003 experiment. The pattern of lower survival in colder temperature regimes held through mid-winter, with 76% survival (warm regime), 62% (intermediate), and 29% (cold). Likewise, during the 2004 experiment, survival to early winter ranged from 44% (warm regime) to 10% (cold). Most mortality in all treatments occurred during a recruitment bottleneck encompassing a 4- to 6-week period following swimup. A response surface analysis of percent dry weight data indicated that the energy content of fry at swimup was lower in colder regimes, and declined during the recruitment bottleneck in all regimes. In the field, I monitored temperatures and conducted surveys to estimate densities of age-0 fry at peak emergence in six headwater streams that varied in thermal characteristics. Density and growth increased with Celsius degree days during the growing season. My results indicate a strong recruitment bottleneck after swimup, when temperature-related energy deficits probably cause significant mortality. Fisheries managers in the southern Rocky Mountains may increase translocation success of native cutthroat trout by selecting sites with ≥800-900 degree days during the growing season, and fry grow to ≥30-35 mm by the end of the growing season.Item Open Access Effects of groundwater withdrawal and drought on native fishes and their habitats in the Arikaree River, Colorado(Colorado State University. Libraries, 2009) Falke, Jeffrey Arron, author; Fausch, Kurt D., advisorGreat Plains streams are harsh environments for fishes, and are increasingly degraded by human-caused impacts, including overuse of groundwater. Plains stream fishes are in decline, due in part to interactions between natural drought and anthropogenic stream drying. To address these issues, in a collaborative study we developed a model of groundwater and surface water that predicted fish habitat quantity within the Arikaree River basin in eastern Colorado into the future, based upon three scenarios of land and water use (e.g., irrigation pumping). We found that under the status quo of pumping, >50% of remaining refuge habitats in the wettest segment of river will be dry in 35 years, and will be isolated in a 1-km fragment along the river. Loss of critical habitats due to stream dewatering, and subsequent negative effects on native fishes, are not unique to eastern Colorado but are in fact widespread across the western Great Plains. Secondly, to set this research in context, I conducted a review of metapopulation and metacommunity research in the stream fish literature. Stream fish populations and communities are spatially structured at multiple scales, and easily fragmented. To date, this spatial structure has not been incorporated into stream fish population and community models. However, recent research in this area should improve our understanding of processes that regulate stream fish assemblages. Next, I developed a spawning phenology for Arikaree River fishes and found that cumulative growing season degree days had the strongest effect on hatching initiation. Occupancy by larvae of most species was related to local scale spawning habitat characteristics (e.g., habitat size and type). Among years, colonization and extinction rates for individual species differed in segments that were fed by groundwater, versus those that were not, and were influenced by climate variability among years. Last, I investigated when and where the threatened brassy minnow, Hybognathus hankinsoni, spawns, and what environmental factors influence growth and survival of this species within and among years. Interannual variability in climate, and the hydrologic context of segments along the riverscape, had a strong influence on habitat availability and recruitment of brassy minnow in the Arikaree River.