• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 71
  • 1
  • Tagged with
  • 259
  • 259
  • 134
  • 76
  • 71
  • 66
  • 48
  • 42
  • 34
  • 32
  • 30
  • 28
  • 28
  • 23
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An Evaluation of Stress Induced Mortality of Stocked Catchable-Sized Rainbow Trout in Temple Fork of the Logan River

Gresswell, Robert Earl 01 May 1973 (has links)
The level of stress imposed by population pressure, handling and live transportation on planted catchable-sized rainbow trout in a northern Utah stream was examined. Production of adrenocorticotrophin, as measured by interrenal ascorbic acid and serum cortisol levels, did not occur in transported or planted fish. Dead or moribund fish collected from stream or live boxes comprised 13 percent of the 2,000 fish planted. Aeromonas salmonicida, the causative agent of furunculosis, was isolated from 41 percent of 106 moribund fish sampled. In addition, 39 percent of the samples exhibited bacterial growth other than A. salmonicida. Apparently, handling, transportation, and planting did cause low levels of stress sufficient enough to induce stress-mediated diseases such as furunculosis.
2

Captive Propagation of Tangerine Darters for Re-introduction in the Pigeon River, Tennessee

Phillips, Craig Lee 01 May 2007 (has links)
The Pigeon River suffered major water quality degradation from 1908 through the 1980’s from paper mill effluent which resulted in the extirpation of many native fish species. Mill modifications have cleaned the effluent to the degree where some native species are recolonizing many areas of the river. In 2001, the Pigeon River Restoration Project was initiated to re-introduce native non-game species which have been unable to return of their own accord. In addition to relocation of selected suitable species, captive production of the tangerine darter (Percina aurantiaca) has been attempted since current translocation methods have proven impractical due to the small number found in the Pigeon River system. It is anticipated that, through hatchery propagation, sufficient numbers of tangerine darters might be produced for re-introduction. This method has seen limited success with other Percina species. Using brood stock of tangerine darters collected from the Pigeon River above the paper mill, three attempts to spawn and propagate tangerine darters were conducted at the Conservation Fisheries Incorporated (CFI) facility in Knoxville, TN. In the first trial, no eggs were spawned; the second year produced approximately 290 eggs and larvae but relatively few survived. The third attempt produced approximately 331 eggs and larvae, resulting in approximately 85 juveniles, but grow-out was problematic; future propagation efforts will target optimum grow-out densities as well as determine the nutrition requirements for larval and juvenile tangerine darters.
3

Fish Production and Movements in the Lower Logan River, Utah

Bergersen, Eric P. 01 May 1973 (has links)
Following the abatement of domestic sewage pollution xii in the lower Logan River , the fish population was investigated in terms of abundance, growth, fecundity, production, mortality, age class structure, species diversity, distribution and movements during 1970 and 1971. Three general groupings of fish were identified in the study area on the basis of species composition, abundance and distribution using a cluster analysis technique. These were located in 1) the tributary stream (7-Mile Creek) which previously transported sewage to the river and 2) above and 3) below 7-Mile Creek in the main stream of the Logan River. A "transition" population was present in the river near the confluence of 7-Mile Creek. Species diversity was predictable on the basis of four physical variables including percent riffle, a measure of bank cover, stream sinuosity and gradient. Percent riffle appeared to be the most important variable in predicting the "Trophic Condition Index" of the fish population. An information theory function was used to determine the extent of fish movement within the study area. Of the four dominant species in the river (carp, mountain whitefish, Utah suckers and brown trout) only the brown trout demonstrated an apparent response to the pollution abatement by reducing the extent of its movements at this time. Seasonal growth patterns were strikingly similar among the species examined with maximum growth occurring during the spring months. Extensive weight losses, attributed to high population densities and a decline in the invertebrate forage base, occurred during the summer of both 1970 and 1971, particularly in the older age classes of mountain whitefish and brown trout. Production of carp, mountain whitefish and brown trout and Utah suckers was assumed to approximate total fish production in the river. Whitefish production above and below 7-Mile Creek was estimated to be 3. 87 and 1.65 gm/m 2/yr respe ctive ly for the period June 1970 to May 1971. Carp production in these two areas was estimated to be 22.86 and 10.45 gm/m 2/yr for the same period. Brown trout production was estimated to be 5.94 gm/m 2/yr above 7-Mile Creek while production of Utah suckers in the study area was estimated to be 2-3 gm/m 2/yr. Weighted production for the entire study area was estimated to be 23.5 gm/m 2/yr. Evidence is presented which suggests that fish production has increased following the pollution abatement.
4

Age and Growth of the Green Sunfish Lepomis cyanellus Rafinesque in Northern Utah

Wright, Young E. 01 May 1951 (has links)
The green sunfish Lepomis cyanellus Rafinesque is a member of the sunfish family Centrarchidae. Curtis states that all members of the sunfish family are native only to North America, and are primarily warm-water fish. According to Jordan and Evermann the green sunfish is generally abundant in all suitable waters from central Ohio and Indiana to the Rio Grande. Forbes and Richardson five the general distribution of the green sunfish to be from the Great Lakes to Mexico, the Mississippi Valley, and everywhere in small sluggish streams except east of the Alleghanies and in Canada. The green sunfish is not native to Utah, but has been introduced in a number of ponds in the state. It is not considered important as a pan-fish because of its limited range and small size.
5

Movement Patterns and Multi-Scale Factors That Influence Exotic Brook Trout And Endemic Bonneville Cutthroat Trout Distribution And Abundance In The Mill Creek Drainage, Utah

Nadolski, Benjamin Keith 01 December 2008 (has links)
Introduced brook trout (Salvelinus fontinalis) are implicated as a primary factor leading to the decline in distribution and abundance of native cutthroat trout (Oncorhynchus clarkii). However, not all introductions are successful, suggesting local conditions influence the success of invasions. Therefore, I sought to determine the multi-scale factor(s) that influence brook trouts’ invasion success of native Bonneville cutthroat trout (Oncorhynchus clarkii utah) habitats in Mill Creek, Utah. I conducted patch occupancy surveys to determine watershed-scale brook trout and cutthroat trout distribution. I also determined the relative abundance of brook trout and cutthroat trout at the reach-scale by conducting three-pass depletion electrofishing surveys at ten index sites throughout the drainage. Upon completion of those surveys, I collected key watershed and reach-scale biotic and abiotic data twice during base-flow conditions. In addition, to determine watershed-scale population connectivity and the potential for upstream invasion by brook trout, I assessed fish movement using two-way weir traps. At the watershed-scale, stream slope appeared to limit brook trout invasion into some portions of the drainage. Intermittent stream-flows and extreme levels of stream slope (> 10%) appeared to limit cutthroat trout distribution. At the reach-scale, regression analyses indicated aquatic invertebrate abundance and low winter water temperatures may have influenced the abundance of brook trout, but my models explained little variation in cutthroat trout abundance overall. I observed high rates (74%) of site fidelity amongst brook trout, and mobile brook trout moved short distances (range=62-589 meters) overall. Cutthroat trout also exhibited high site fidelity (92%), but their movement was more variable, as few individuals moved long distances (up to 12.15 km). These findings will help prioritize cutthroat trout management actions in this watershed, and will be useful in determining why brook trout are successful invaders in some systems, yet remain in low and patchy abundance in others.
6

Multiple Hemoglobins in Rainbow Trout, Salmo gairdneri, and Cutthroat Trout, Salmo clarkii

Braman, Jeffrey Carl 01 May 1976 (has links)
Nine hemoglobins from adult rainbow trout have been isolated by starch gel electrophoresis using a Trisborate buffer system, pH 8.7. Six fast and two slow anodally migrating hemoglobins, and one slow cathodally migrating hemoglobin were observed in all specimens. The nine hemoglobins have been purified by DEAE cellulose ion exchange chromatography followed by starch gel electrophoresis. The subunit structure of each purified hemoglobin has been partially examined by gel electrofocusing (GEF) in .5 percent polyacrylamide gels containing 8M urea and lmM dithiothereitol (DTT). Tetrameric combinations of one, two, three, and four polypeptide chains are present. Twelve hemoglobins have been isolated from cutthroat trout. Six fast and two slow anodally migrating hemoglobins, and four cathodally migrating hemoglobins were observed in most of the specimens. Hemoglobin polymorphism has been detected in a population of Yellowstone Lake cutthroat trout, Yellowstone Park, Wyoming. Six phenotypic patterns were evident.
7

Ontogeny of the Sexually Dimorphic Sonic Muscle in Three Sciaenid Species

Hill, Gary 01 January 1985 (has links)
No description available.
8

Seasonal Movements, Habitat Utilization, and Comparative Scale Morphology of White Marlin (Kajikia albida) and Roundscale Spearfish (Tetrapturus georgii)

Loose, Emily L. 01 January 2014 (has links)
Recent studies have demonstrated that the morphologically similar white marlin (Kajikia albida) and roundscale spearfish (Tetrapturus georgii) co-occur in the western North Atlantic, including the U.S. Mid‐Atlantic Bight. Differences in scale morphology have been proposed as one morphological character to discriminate these species, but a thorough analysis of scale morphology is lacking. Because the validity of the roundscale spearfish was not established until 2006, much of the biological information previously collected for “white marlin” may include data for both white marlin and roundscale spearfish. The objectives of this study were to obtain a better understanding of the movements and habitat utilization of positively identified white marlin that inhabit the U.S. Mid-­‐Atlantic Bight during summer months, and to describe the morphological variation of white marlin and roundscale spearfish scales. Eleven long‐term (6 or 12 month) pop-up satellite archival tags were placed on white marlin that were caught and released in the U.S. recreational fishery. Nine tags reported information on temperature, pressure (depth), and light levels for light‐based geolocation for periods of 8 days to 12 months. Most fish moved out of the Mid-Atlantic Bight in September, and overwintered in areas ranging from east of the Gulf Stream off the Carolinas to the Caribbean, and as far south as northern Brazil. of the seven fish that retained tags for more than 40 days, five spent time in known spawning grounds in waters of the Dominican Republic leading up to the spring spawning season. These data demonstrate a large degree of connectivity among white marlin in the western North Atlantic. as noted in previous studies, individuals spent a large proportion of their time in the surface waters (0-10m; 75% across all white marlin pooled), the vast majority of their time in the top 100 m of the water column (97%), and within eight degrees of sea surface temperature (98%), although definite shifts in habitat utilization were evident as fish departed coastal offshore waters of the Mid‐Atlantic Bight. Diel habitat utilization varied greatly, with white marlin spending 81% of total nighttime in the surface waters (0‐10m), and only 26% of total daytime in surface waters. Past studies have characterized the scales of white marlin and roundscale spearfish as being morphologically distinct, but little effort has been made to describe variation within an individual, among individuals, or between species. to better understand morphological variation of scales and squamation patterns of distinct body regions of these two species, individual scales were collected from 11 specific anatomical regions, and scale patches were collected from 3 specific regions of each white marlin and roundscale spearfish brought into marlin tournament weigh stations in the Mid-Atlantic Bight during 2012 and 2013. Scales were measured and described, and scale patches were cleared and stained to examine the level of imbrication of the scales, as well as the overall squamation patterns. In addition to the scales, denticular plates, ossified formations occurring on the surface layer of the dermis, were measured and described. Although considable morphological variation was observed among scales from different anatomical regions of individuals of both species, white marlin scales generally have pointed anterior ends, fewer posterior points, and are more heavily imbricated than those of roundscale spearfish, which are frequently rounded anteriorly, but often have many posterior points and are farther separated within the skin. Over all areas and individuals, roundscale spearfish scales were significantly wider and had a lower length-­‐to-­‐width aspect ratio than those of white marlin. Detailed scale descriptions allow for a more accurate characterization of the variation within and differences between these two species, and could potentially be a valuable tool for investigating istiophorid systematics.
9

Observations on the Winter Trawl Fishery for Summer Flounder, Paralichthys dentatus

Eldridge, Peter J. 01 January 1962 (has links)
No description available.
10

The Biology of the Utah Chub, Gila Atraria (Girard), of Scofield Reservoir, Utah

Olson, Harold F. 01 May 1959 (has links)
The Utah chub is one of the most important non-game fish in Utah. It has a wide range, and occurs in every drainage in Utah. The Utah chub is not important economically as food fish nor is it of much value commercially. The sportsmen think of this species as trash and do not consider catching or consuming the. However, the Utah chub may be caught on hook and like more readily than many game species. The Utah chub in Scofield Reservoir have been caught by trolling, bait fishing and fly casting and furnish considerable sport when caught with a light tackle. Their real importance becomes evident when a large population of Utah chub exist in waters where game fish species are desired. With their high reproductive potential, the Utah chub may become the dominant species and cause trout populations to decrease. This competition for food and space has been evident in many areas. Hazzard (1935) stated that Utah chub and trout compete with trout for food in Fish Lake, Utah, and Sigler (1948) also found that Utah chub compete with trout for food.

Page generated in 0.1348 seconds