Life Sciences Commons^™

An Empirical Model Of Gastric Evacuation Rates For Fish And An Analysis Of Digestion In Piscivorous Brown Trout, E. He, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

The gastric evacuation rates of brown trout Salmo trutta (0.9–1.6 kg) feeding on fingerling rainbow trout Oncorhynchus mykiss (3.5–7.6 g) were measured in the laboratory at five temperatures (4.5, 9.0, 14.0, 19.0, and 22.5°C). Instantaneous gut evacuation rates (Re) increased exponentially with temperature (T): Re = 0.053se^0.073T, r^2 = 0.98; they varyied from 7%sh^–1 at 4.5°C to 29%sh^–1 at 22.5°C. Linear regressions described the relationship between time and qualitative measures of fish digestion, thus allowing investigators to determine how long an ingested fish would be identifiable at different temperatures. An analysis of published evacuation rates (N = 121) of 22 …

A Trophic Gradient Analysis Of Lake Powell During Spring Runnoff 1992, Wayne A. Wurtsbaugh, Clyde Lay, Darren Carlise, Corey Huxol, Craig Schaugaard, Beau Clements, David Beauchamp

Watershed Sciences Faculty Publications

Between 26 April and 2 May 1992, students in a utah state university aquatic ecology class visited Lake Powell to do a study of trophic gradients of the reservoir. The main axis of the reservoir was surveyed, as well as less detailed analyses of Moki and Escalante Canyons. The work was conducted in collaboration with personnel from the u.s. Bureau of Reclamation headed by Bill Vernieu, and from the u.s. Geological Survey (Dick Marzolf). Some of their data appear in the physical-chemical section of this report.

Each student was responsible for compiling a report on one of the following specific …

Snake River Sockeye Salmon (Oncorhynchus Nerka) Habitat/Limnologic Research, Scott Spaulding, Wayne A. Wurtsbaugh, Shoshone-Bannock Tribe

Watershed Sciences Faculty Publications

This report outlines long-term planning and monitoring activities that occurred in 1991 and 1992 in the Stanley Basin Lakes of the upper Salmon River, Idaho for the purpose of sockeye salmon (Oncorhynchus nerka) recovery. Limnological monitoring and experimental sampling protocol, designed to establish a limnological baseline and to evaluate sockeye salmon production capability of the lakes, are present:ed. Also presented are recommended passage improvements for current fish passage barriers/impediments on migratory routes to the lakes. We initiated O. Nerka population evaluations for Redfish and Alturas lakes; this included population estimates of emerging kokanee fry entering each lake in the spring …

Soil Chemistry And Nutrition Of North American Red Spruce-Fir Stands: Evidence For Recent Change, J. D. Joslin, J. M. Kelly, H. Van Miegroet

Watershed Sciences Faculty Publications

One set of hypotheses offered to explain the decline of red spruce (Picea rubens Sarg.) in eastern North America focuses on the effect of acidic deposition on soil chemistry changes that may affect nutrient availability and root function. Long-term soils data suggest that soil acidification has occurred in some spruce stands over the past 50 yr, with plant uptake and cation leaching both contributing to the loss of cations. Studies of tree ring chemistry also have indicated changes in Ca/Al and Mg/Al ratios in red spruce wood, suggesting increases in the ionic strength of soil solution. Irrigation studies using strong …

Soil Nitrogen Dynamics Following Harvesting And Conversion Of Red Alder And Douglas-Fir Stands, H. Van Miegroet, P. S. Homann, D. W. Cole

Watershed Sciences Faculty Publications

Drastic reductions in NO3- leaching have been observed after harvesting of mature red alder (Alnus rubra Bong.) stands. Our objective was to examine whether these reduction were linked to changes in soil N dynamics. Adjacent alder and Douglas fir [Pseudotsuga menziessii (Mirbel.) Franco] stands on young glacial soils (Alderwood; a loamy-skeletal, mixed, mesic, ortstein Aquic Haplorthod) in western Washington were harvested and replanted with either alder or Douglas fir seedlings; reference plots were established in nearby undisturbed stands. Three years after site conversion, when NO3- leaching declined most drastically in the harvested alder plots, net N mineralization and net nitrification …

Visual Feeding By Juvenile Bear Lake Sculpin, D. Neverman, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Young-of-the-year Bear Lake sculpin Cottus extensus feed throughout the day on benthic invertebrates and cease feeding at night when they migrate to the metalimnion. We investigated their reliance on vision by conducting feeding trials at different light levels in the laboratory. Feeding rate reached a maximum at intermediate light levels (near 10^16 photons sm^–2 ss^–1; approximately 1 lux) but decreased as light intensity increased beyond this range. At this maximum rate, the fish fed nine times faster than they were able to feed in the dark, showing that young Bear Lake sculpin rely heavily upon vision to feed. The light …

Lake Trout Spawning In Lake Tahoe: Egg Incubation In Deepwater Macrophyte Beds, D. A. Beauchamp, B. C. Allen, R. C. Richards, Wayne A. Wurtsbaugh, C. R. Goldman

Watershed Sciences Faculty Publications

Although most populations of lake trout Salvelinus namaycush spawn over rocky shoals, use of these substrates by lake trout has not yet been found in Lake Tahoe. Large cobble substrate exists at depths less than 20 m, and steep, fractured, rocky substrate can be found in isolated areas from the surface down to at least 100 m, but no evidence of spawning activity in these areas has been found. Instead, at least a portion of the population spawns on deepwater mounds (40–60 m deep) over beds of the macrophyte Chara delicatula. This is the first known report of lake trout …

Predation Risk And The Importance Of Cover For Juvenile Rainbow Trout In Lentic Systems, R. A. Tabor, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Juvenile rainbow trout Oncorhynchus mykiss stocked in midelevation reservoirs in Utah inhabit shallow nearshore areas and are vulnerable to predation from piscivorous fish and birds. We determined the use and importance of nearshore habitats by (1) measuring habitat selection by, prey availability to, and feeding of juvenile rainbow trout in two reservoirs with populations of predators, and (2) measuring survival and growth rates in the presence and absence of cover in a pond experiment where adult brown trout Salmo trutta were predators. In the reservoirs juvenile rainbow trout (60–120 mm standard length) were abundant in complex inshore habitats but avoided …

Trophic Interactions Between Fish And Invertebrates In Bear Lake, Utah-Idaho, Wayne A. Wurtsbaugh, Charles P. Hawkins

Watershed Sciences Faculty Publications

An intensive study of the limnology, invertebrates and fishes of Bear Lake was conducted in 1987 in order to define the productivity and food web of the community. Limno10gica1 parameters and invertebrates were measured at approximately monthly intervals while fish distribution and feeding was analyzed in February, June, August, and October. Samples were collected at three to eight stations along a transect running from the shallow littoral area on the west side of the lake, to the deep profundal zone.

Survival Of Trout Strains As Affected By Limnological Parameters, Wayne A. Wurtsbaugh, Timothy Modde, Chris Luecke, Cheryl Courtney

Watershed Sciences Faculty Publications

Juvenile rainbow trout Oncorhynchus mykiss. (ca. 80 mm S.L.) stocked into mid-elevation reservoirs in Utah are vulnerable to predation from piscivorous fish and birds. I determined how effectively juvenile trout used cover to avoid these predators by using direct observations (snorkel transects) on habitat selection in two reservoirs. Observations of juvenile trout were conducted within five weeks of stocking in 1988 and 1989. During the day juvenile trout were abundant in complex inshore habitats. Juvenile trout actively fed during the day but the time of peak feeding was variable. Large Daphnia made of > 95% of the diet of juvenile trout. …

Survival Of Trout Strains As Affected By Limnological Parameters, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Prior work at East Canyon Reservoir, Utah indicated that adult trout are important predators of stocked juvenile rainbow trout. Brown trout, in particular, were exclusively piscivorous when th~y exceeded 185 mm standard length. Fish became increasingly important in the diet of cutthroat trout greater than 330 mm. The purpose of this study was to further document the effect of adult trout on survival of juvenile rainbow trout in mid-elevation reservoirs. Causey Reservoir was chosen because it was thought to contain large brown and cutthroat trout and had not been intensively studied during the last eight years.

A Mass Mortality Of Fishes In Lake Titicaca (Peru-Bolivia) Associated With The Protozoan Parasite Ichthyophthirius Multifiliis, Wayne A. Wurtsbaugh, R. Alfaro

Watershed Sciences Faculty Publications

In December 1981 , an epizootic of the protozoan parasite Ichthyophthirius multifiliis killed an estimated 18 million killifish Orestias spp. in Lake Titicaca, a high-altitude tropical system. Of the dead fish collected, 93% were adult O. agassii, a commercially important species that is abundant in the littoral zone. Juvenile Orestias spp., pelagic species, and some other littoral zone fis hes were slightly affected. lchthyophthirius multifiliis was probably introduced with exotic fishes brought to Lake Titicaca in the 1940s and 1950s.

Microhabitat Selection And Diel Movements Of Juvenile Rainbow Trout (Salmo Gairdneri) Introduced Into Mid-Elevation Reservoirs In Utah, Wayne A. Wurtsbaugh, Roger Tabor

Watershed Sciences Faculty Publications

The distribution and movement patterns of fingerling rainbow trout stocked into reservoirs in Utah were investigated with · SCUBA observations and by vertical gill netting. For several weeks after stocking, fingerling trout (ca. 80 mm standard length) were strongly oriented to the shore, and selected habitats providing cover. During the underwater observations, no fish were seen below depths of 2 meters. Two weeks after stocking, the fingerlings were most abundant under docks near where they were planted, indicating that dispersal was relatively slow. Jacob's electivity indices for natural substrates in water 0-1.5 meter deep were in sand, gravel, cobble, boulders …

Importance Of Predation By Adult Trout On Mortality Rates Of Fingerling Rainbow Trout Stocked In East Canyon Reservoir, Utah, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Personnel from Utah State University, working in cooperation with the Utah Division of Wildlife Resources and the Utah Cooperative Fish and Wildlife Research Unit, are attempting to determine various sources of mortality of fingerling rainbow trout (Salmo gairdneri) stocked into mid-elevation reservoirs in the State. Returns of planted fish are often much below desired levels. Angler surveys indicate that in East Canyon Reservoir, fishermen harvest only about 30% of the fingerling trout stocked, and this is a much higher return than in many other waters.

Factors Affecting Anion Movement And Retention In Four Forest Soils, D. W. Johnson, D. W. Cole, H. Van Miegroet, F. W. Horng

Watershed Sciences Faculty Publications

Three hypotheses concerning the movement and retention of anions in forest soils were tested in a series of laboratory and field studies on two Tennessee Ultisols with mixed deciduous forest cover and two Washington Inceptisols, one with deciduous (red alder Alnus rubra Bong.) and one with coniferous [Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco] forest cover. The first hypothesis, that sulfate and phosphate retention was related to adsorption to free Fe and Al oxides, which were in turn related to soil parent material and degree of weathering, was not supported by results of laboratory and field studies. The young, relatively unweathered Washington …

The Vertical Distribution And Feeding Chronology Of Larval Bear Lake Sculpin (Cottus Extensus) In Bear Lake, Utah-Idaho, D. Neverman Devroy, Wayne A. Wurtsbaugh, S. Ohlhorst

Watershed Sciences Faculty Publications

Preliminary sampling in Bear Lake, Utah/Idaho, with bottom trawls and larval fish nets indicate