• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 7
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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

The bacteriology of Atlantic halibut, Hippoglossus hippoglossus (L.) larval rearing

Verner-Jeffreys, David Willoughby January 2000 (has links)
No description available.
2

Studies on the effects of environmental factors and selected pathogens on morbidity and mortality of hatchery reared Oreochromis mossambicus (Peters) eggs and fry

Subasinghe, R. P. January 1986 (has links)
No description available.
3

Some Factors which May Influence Survival of Game Farm-Reared Pheasants after Release into the Wild

Cottle, Taylor F. 01 May 1950 (has links)
This study was undertaken in an attempt to determine some of the factors which may influence the survival of Utah game farm-reared pheasants following their release into the wild. The survival of these birds is below the desired level after they are released, as is indicated by the low percentage taken by the sportsmen during the hunting season. In recent years the return from released game farm-reared pheasants is about 7 to 8 percent. Consequently, if survival rate of these birds could be increased, more birds would be available to supplement the wild stock. Also, an increase in the pheasant population throughout the state would make more birds available to sportsmen during the hunting season.
4

Investigation of Urolithiasis Occurring In Hatchery-Reared Trout in Utah

Dean, Ernest H., Jr. 01 May 1971 (has links)
The urolithiasis condition investigated occurred at a "hard water" hatchery in Utah after the trout were changed from a meat diet to a commercial pelleted fish feed as a sole sustaining diet in 1961. Numerous diet modifications proved unsuccessful in preventing urolithiasis at the hatchery. It was eventually determined that different commercial diets resulted in varied percentages of trout developing urolithiasis. The urolithic deposits found in the kidney tubules were amorphous and composed of calcium phosphate (apatite) and an organic matrix. Bacterial contamination of the kidneys was not an important factor in the formation of urolithiasis. Rainbow trout containing urolithic deposits showed gradual deposit regression when transferred into a "softer" water supply. Pelleted experimental diets containing sodium bicarbonate and/or sodium fluoride were fed to two strains of rainbow trout reared in a "softer" water supply normally causing no urolithiasis problems. The diets with the sodium bicarbonate added resulted in a significant occurrence of urolithiasis when fed to trout for 30 days. The addition of sodium fluoride to the diet was not significant in producing urolithiasis in trout. One experimental diet (low sodium bicarbonate-sodium fluoride) and one strain of fish (Soap Lake) appeared to influence the number of trout developing urolithiasis although the increase was not significant. All levels of statistical significance were tested at the 5 percent level.
5

Environment-induced Phenotypic Plasticity in the Teeth of Hatchery and Wild Largemouth Bass, <i>Micropterus floridanus</i>

Selvaraj, Tamilselvi 01 August 2010 (has links)
Successful stock enhancement of hatchery-reared fish depends heavily on the release of individuals able to demonstrate strong survival skills. Overall survival of fishes is a reflection of a successful blend of physiology, anatomy, and behavior. With fishes being highly phenotypically plastic, the potential exists for all aspects of hatcheryreared fish to vary significantly from their wild counterparts while having potentially adverse effects on their survival after release. Previous analyses have demonstrated significant differences between the feeding behavior of hatchery-reared and wild caught largemouth bass (Micropterus floridanus) in the laboratory, as well as differences in the development of the skull between these two groups. The aim of this study was to determine if oral and pharyngeal jaw dentition differed between hatchery and wild bass. Scanning electron micrographs of the oral and pharyngeal jaws from an overlapping size range of 30 hatchery-reared and 30 wild bass were compared for the number and characteristics of oral and pharyngeal teeth. Wild bass were found to have features which would presumably allow more efficient capture of prey. The results of the study suggested that wild bass exhibited greater number of teeth when compared to hatchery reared bass. They also exhibited oral and pharyngeal teeth which were greater in length, and pharyngeal teeth that were greater in width when compared to hatchery-reared bass. This deficiency in dentition could have a significant effect on prey-capture success when introduced into the wild. We suggest that exposure to wild prey during the grow-out phase of aquaculture could provide the necessary adaptive plasticity of hatchery-reared bass dentition
6

Experimental release of hand-reared wolf pups in Tver region (Russia): food habits, movement patterns and fear of humans.

Fraissard, camille January 2011 (has links)
Studying the reintroduction of hand-raised wolves may embrace several interests such as deepening knowledge on wolf biology and allowing a controlled release in isolated populations in need of genetic influx. Studies on hand-raised wild animals, showing successful reintroduction, suggested that young released wolves might be able to survive in the wild without previous fastidious training. Most of their survival behaviours would be instinctive. In this study, nine young wolves were reintroduced in Tver region (Russia) and followed in order to evaluate their fear of humans, their movement patterns, thanks to GPS-Argos collars fitted to three of the animals, and assess their diet via four methods of scats analysis. We analyzed 46 wolf scats collected from August 2010 to January 2011. We determined the frequency of occurrences of items per scats and per items, and used the Relative Estimated Bulk to estimate the biomass of prey species consumed. Statistics were conducted to test for significance of method comparisons. The results showed that half of the wolves remained near the enclosure weeks to months after release, occasionally leaving the vicinity. The individual wolves behaved differently, they adopted various movement patterns and had diverse home ranges (from 15 km2 to 40 km2). Released wolves preyed more on ungulates, especially moose and on other wild mammals such as mountain hare. They also sporadically hunted domestic animals and regularly consumed vegetal matter along with smaller animals as alternative prey. Finally, all scat-analysis methods significantly assessed (p &lt; 0.01) the relative importance of the main food types.
7

The Bobwhite Population Decline: Its History, Genetic Consequences, and Studies on Techniques for Locating and Assessing Current Populations

Whitt, Jeffrey Glen 05 1900 (has links)
The northern bobwhite (Colinus virginianus) population decline is a severe, rangewide phenomenon beginning >150 years ago and continuing today. In this investigation, I: 1. document the timeline of bobwhite population decline and unintended genetic consequences of attempted remedies, 2) develop a model useful for predicting possible locations of potentially sustainable bobwhite populations in semiarid rangeland in Texas and Oklahoma, and 3) examine the relationship between population monitoring data and meteorological factors. While breeding season call counts of male bobwhite have been used for >70 years to provide estimates of fall populations for hunting, most studies of call counts have focused on mathematics and statistical accuracy of the count, largely overlooking the influence of meteorological factors on call counts. Here, I present the results of >4,400 individual point counts and examine their relationship with meteorological variables recorded at each stop. Humidity was positively correlated with the number of birds recorded (ρ = 0.275, p < 0.001) and temperature was negatively correlated (ρ = -0.252, p < 0.001). The number of birds recorded was significantly higher in wet years than in drought years. There was no significant correlation between wind velocity and number of birds recorded. These results suggest that, while weather does influence call counts and efforts should be made to record meteorological conditions when collecting call count data, the influence of weather may not easily factor into the analysis. These results also provide another line of evidence for decreased breeding behavior during high temperatures. With the increased focus on bobwhite habitat management on a regional scale, there is a need for reliable methods to identify potential bobwhite habitat. To identify bobwhite habitat in semiarid rangeland, I performed classification of LANDSAT scenes of Clay County, Texas from July and December 2015. Stands of mature little bluestem provide excellent bobwhite nesting cover and could be identified using LANDSAT imagery. I scored habitat by type, compared these scores with the results of breeding season call counts from 2014 and 2015 and found significant correlation. When used in combination with other landscape data, this approach can provide a regional context to inform conservation and management decisions.

Page generated in 0.0394 seconds