Download or read book Trophic Ecology of Lake Trout Salvelinus Namaycush in Flaming Gorge Reservoir Utah Wyoming written by Thomas C. Roberts and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake Trout (Salvelinus namaycush) are apex predators that were first introduced into Flaming Gorge Reservoir, Utah-Wyoming in 1979 and have been self-sustaining since 1989. However, our understanding of their trophic ecology and subsequent effects on other fish species within this reservoir is limited. I assessed feeding dynamics of Lake Trout through traditional diet analyses and stable isotope analyses of muscle and liver tissues, and compare these outputs to patterns of Lake Trout growth rates and size structure. By integrating Lake Trout feeding dynamics with population demographics, I infer potential impacts of Lake Trout predation on prey fish. Lake Trout consumed a wide breadth of prey items across their ontogeny, but consumed a higher proportion of fish as their length increased. Stable isotope analyses suggested a higher reliance on fish prey than was described by stomach content analysis; however, estimates of feeding dynamics were comparable across methods. Growth models suggest that Lake Trout exhibited two distinct growth trajectories which indicate a divergent foraging strategy among individuals. I conclude that Lake Trout predation could be an important driver of game and non-game fish populations. While more information is needed, results suggest current length class definitions used for Lake Trout harvest regulations may not reflect observed ecological breakpoints. Further research such as bioenergetics modeling and fishing related mortality estimates are needed to fully understand ecological dynamics of this apex predator within Flaming Gorge Reservoir.
Download or read book Investigations of Forage Fish and Lake Trout Salvelinus Namaycush Interactions in Flaming Gorge Reservior Wyoming Utah written by Daniel L. Yule and published by . This book was released on 1992 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Lake Trout written by Russell Daly and published by . This book was released on 1962 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduced Lake Trout Produced a Four level Trophic Cascade in Yellowstone Lake written by Lusha Marguerite Tronstad and published by . This book was released on 2010 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction of lake trout Salvelinus namaycush into a system can add a trophic level, potentially affecting organisms at lower trophic levels. Similar to many lakes and reservoirs in the western United States, lake trout were introduced into Yellowstone Lake, Wyoming. Previous studies showed that lake trout reduced the population and altered the size structure of native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri in Yellowstone Lake, but we sought to determine the degree to which lake trout predation changed lower trophic levels. We predicted that the structure of lower trophic levels would change in conformance with trophic cascade theory because Yellowstone cutthroat trout consume zooplankton. We compared zooplankton and phytoplankton assemblages between the period when Yellowstone cutthroat trout were abundant and the period after they declined. As predicted by trophic cascade theory, zooplankton biomass shifted from being dominated by copepods before lake trout introduction to being dominated by cladocerans after lake trout introduction, with zooplankton body lengths 17% longer after introduction. Vertical water clarity increased by 1.6 m because of a twofold decrease in chlorophyll a and a three- to sevenfold decrease in phytoplankton biovolume. Thus, the introduction of lake trout and subsequent decline of Yellowstone cutthroat trout likely altered lower trophic levels in Yellowstone Lake. Trophic cascades may be common in western U.S. lakes and reservoirs where native salmonids are present and where lake trout have been introduced.
Download or read book Biology of Young Lake Trout Salvelinus Namaycush in Lake Michigan written by John Van Oosten and published by . This book was released on 1956 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental fishing with gill nets of 5 mesh sizes (2 3/8 to 3 inches) in Lake Michigan in 1930-32 yielded more than 16,000 young lake trout. Data are presented here on age, growth, length-weight relationship, abundance, geographical and bathymetric distribution, and other details of their biology.
Download or read book Chlorinated Hydrocarbons as a Factor in the Reproduction and Survival of Lake Trout Salvelinus Namaycush in Lake Michigan written by and published by . This book was released on 1981 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rapid Trophic Recovery of Lake Trout Salvelinus Namaycush in Response to Removal of an Introduced Predator written by Jesse Michael Lepak and published by . This book was released on 2004 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Three Strains of Rainbow Trout in Flaming Gorge Reservoir Utah Wyoming written by Roger W. Schneidervin and published by . This book was released on 1992 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Factors Affecting the Growth of Rainbow Trout in Flaming Gorge Reservoir Utah Wyoming written by Tyler M. Haddix and published by . This book was released on 2004 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Lake Trout Suppression Methods on Lower Trophic Levels in Yellowstone Lake Wyoming written by Dominique Raquel Lujan and published by . This book was released on 2020 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake trout (Salvelinus namaycush) were unintentionally introduced to Yellowstone Lake, Yellowstone National Park, Wyoming, and drastically reduced the native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) population. Gillnetting suppresses adult lake trout since 1995; however, Yellowstone National Park is developing methods to suppress embryos, including adding lake trout carcasses and analog pellets to spawning sites. Decomposing carcasses and analog pellets cause lake trout embryo mortality due to low dissolved oxygen concentrations, but the effects of these methods on lower trophic levels are unknown. We estimated the degree to which adding carcasses or analog pellets to spawning sites altered nutrient limitation, nutrient concentrations, algal biomass, and ammonium uptake. We deployed nutrient diffusing substrates at three sites (control, carcass, and analog pellets) before and after carcasses or analog pellets were added to measure algal biomass in six treatments where nothing (control), nitrogen, phosphorus, nitrogen and phosphorus, carcasses or pellets were added to agar. We measured nutrient concentrations, algal biomass (chlorophyll a concentrations) and ammonium uptake at spawning sites where no carcasses were added (control), site where carcasses were added before lake trout spawned (early season sites), and sites where carcasses were added after lake trout spawned (late season sites) in 2018 and 2019 to investigate the degree to which carcasses caused bottom-up effects in periphyton and phytoplankton. Nutrient diffusing substrates indicated that nitrogen and phosphorus co-limited periphyton before treatments; however, nutrients were not limiting after carcasses or analog pellets were added to spawning sites. Analog pellets appeared to suppress algal biomass and carcasses increased algal biomass ≥2.4x after their addition. Adding carcasses to shallow spawning sites did not alter the concentration of ammonium, algal biomass or uptake compared to the control site. Periphyton had higher biomass and phytoplankton uptake was much higher. Adding carcasses to the littoral zone likely alters small areas but overall had a small effect on algal biomass and nutrient cycling. Estimating how lake trout suppression methods may alter basal resources in the littoral zone of Yellowstone Lake will help managers develop the best plan to control these invasive predators at early life stages.
Download or read book Biology of Young Lake Trout Salvelinus Namaycush in Lake Michigan written by and published by . This book was released on with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boreal Shield Watersheds written by John Gunn and published by CRC Press. This book was released on 2003-08-27 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boreal Shield Watersheds: Lake Trout Ecosystems in a Changing Environment brings together the work of a renowned international group of scientists who specialize in aquatic science and environmental management. They explore the functioning of Boreal Shield ecosystems, focusing on the lake trout, the classic coldwater species of northern glaciated l
Download or read book Food Habits of Trout in Flaming Gorge Reservoir written by Robert W. Wiley and published by . This book was released on 1973* with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Chemical Markers Identify Source and Date of Introduction of an Exotic Species Lake Trout Salvelinus Namaycush in Yellowstone Lake written by Andrew Roy Munro and published by . This book was released on 2005 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exotic species invasions pose a pervasive threat to aquatic ecosystems worldwide, yet fundamental questions about the geographic origin and timing of invasions or introductions are frequently difficult to answer. We used natural chemical markers (Sr:Ca ratios) in otoliths to identify probable source and date of introduction of exotic lake trout (Salvelinus namaycush) into Yellowstone Lake, Wyoming, USA. Otolith Sr:Ca ratios were significantly different among lake trout known to have reared in three different Yellowstone National Park lakes (Yellowstone, Heart, and Lewis lakes) and showed little variation along the otolith axis, indicating that lake trout within each lake experienced a similar, and consistent, environmental history. In contrast, suspected transplants showed a large and rapid increase in otolith Sr:Ca ratios indicative of a marked shift to water of differing chemistry. Timing of the abrupt change in Sr:Ca ratios indicated that some lake trout were introduced into Yellowstone Lake during the late 1980s, but more recent transplants also occurred. A discriminant model identified Lewis Lake as the likely source lake for lake trout transplanted into Yellowstone Lake. Our results demonstrate that chemical signatures within otoliths can serve as an important forensic tool for identifying the probable source and date of exotic fish introductions.
Download or read book Effects of Introduced Lake Trout on Native Cutthroat Trout in Yellowstone Lake written by James R. Ruzycki and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The establishment of a reproducing population of nonnative lake trout (Salvelinus namaycush) poses a serious threat to the integrity of the Yellowstone Lake ecosystem, particularly to the indigenous cutthroat trout (Oncorhynchus clarki bouvieri). We used standard fisheries techniques to quantify the population-level impact resulting from this introduction, while the U.S. National Park Service (NPS) developed a program to control their numbers. Lake trout diets, thermal history, growth, and size structure were incorporated into a bioenergetics model to estimate the predatory impact of introduced lake trout and to evaluate the effectiveness of the NPS lake trout control program. Population size structures were estimated from catches of fish in gill nets that were corrected for mesh size selectivity. Lake trout abundance was estimated using virtual population (cohort) analysis, and cutthroat trout abundance was estimated using hydroacoustics. Juvenile cutthroat trout were highly vulnerable to predation, and lake trout preyed on cutthroat trout that averaged 27?33% of their body length. Based on our model, an average piscivorous lake trout consumed 41 cutthroat trout each year. During 1996, the piscivorous lake trout population consumed an estimated 15 metric tons of cutthroat trout (129 000 fish) composing 14% of the vulnerable cutthroat trout production. The NPS removed nearly 15 000 lake trout from 1995 to 1999. Had these predators remained in Yellowstone Lake they would have consumed an estimated 23 metric tons of cutthroat trout (200 000 fish) during 1999 alone. If left unchecked, lake trout would clearly pose a serious threat to the long-term existence of the indigenous cutthroat trout. This analysis demonstrates the negative impact of an introduced predator in an ecologically isolated aquatic ecosystem.
Download or read book Model based Exploration of the Variability in Lake Trout Salvelinus Namaycush BAFs Caused by Physiology and Trophic Relationships written by Sivani Baskaran and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because eating fish is often a major vector of human exposure to persistent organic pollutants (POPs), much effort is directed towards a quantitative understanding of fish bioaccumulation using mechanistic models. Many such models fail to consider how uptake and loss rate constants relate to fish physiology. Here, we calculate the bioaccumulation factor (BAF) of hypothetical POPs, with octanol-water partition coefficients values ranging from 104.5 to 108.5, in lake trout (Salvelinus namaycush), with a food web bioaccumulation model that uses bioenergetics to ensure that physiological parameters applied to a species are internally consistent and energetically balanced. Fish in six Canadian lakes were modelled to understand what causes the BAFs of differently sized lake trout to vary between and within lakes. Lake trout activity, diet composition, prey contamination levels and the fraction of the total energy intake spent on growth were found to affect the bioaccumulation potential of chemicals.
Download or read book Spatial and Thermal Ecology of Lake Trout salvelinus Namaycush in Lake Erie written by Tyler R. Funnell and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rehabilitation of lake trout (Salvelinus namaycush), which historically was the coldwater apex predator of much of the Laurentian Great Lakes, is a priority for fishery management agencies in the region. In Lake Erie, the shallowest and southern-most Great Lake, successful rehabilitation of lake trout has been hindered by limited wild recruitment, possibly related to the lake's warm temperatures and restricted oxythermal habitat. I used acoustic telemetry tracking technology to investigate how lake trout spatial and thermal habitat use varies seasonally in Lake Erie to better understand whether limited recruitment could be caused by thermal conditions in the lake. As expected, lake trout were restricted to the offshore region of the eastern basin of Lake Erie during summer stratification. During fall, lake trout tended to occupy the southern nearshore region of the eastern basin, suggesting the importance of focusing spawning habitat restoration in this part of the lake. Tagged fish dispersed long distances at much higher frequencies than other Great Lakes populations of lake trout. Lake trout in Lake Erie occupied thermal habitat similar to other Great Lakes populations during summer stratification. Following destratification in fall, fish were exposed to warm temperatures, in some years for extended periods. Lake trout hatchery strains of Finger Lakes, NY, origin occupied similar summer temperatures and warm temperatures for more days during fall than Great Lakes origin strains, contrary to findings from Lakes Huron and Ontario. These results reveal behaviors that can inform management of lake trout in Lake Erie and throughout the Great Lakes and could begin to explain recruitment failure observed in Lake Erie.
