No description available.

Three hundred rainbow trout from each of two strains (Wytheville and the Soap Lake) were exposed in equal numbers to three non-overlapping wavebands of light (red, green, blue). One hundred fish from each strain were used as a control. These fish were exposed to unfiltered light of intensity equal to that of the three spectral treatments (21.4 lux). All fish were exposed to continuous light of the assigned experimental spectra for 53 days. Fish were fed trout chow twice daily at a rate previously found to maximize growth and efficiency. This feeding rate was determined by consulting hatchery records and the feeding charts developed by Haskell (1959). Mean length and mean weight of test animals may be affected by the rearing of individuals under specific wavebands of light (α = .001). Fish grown under blue or green light had the greatest mean length and fish grown under control or green light had the greatest mean weight while those reared under red light had the lowest mean length and mean weight. Although differences in coefficient of condition, yield, ferd conversion ratio, and survival were not Significant between light treatments (α = 0.05) in my study, significant differences may possibly be found in studies with a larger sample size. Although high variability and small sample size limit interpretation, this study suggests that certain light treatments used in conjunction with certain strains of fish could improve hatchery production. / Master of Science

Strains evaluated were Ennis (EN, domestic), Fish Lake (FL, wild), Mcconaughy (MC, wild), FGL Standard Winter (SW, domestic), and Sand Creek (SC, semiwild). In 1981, four Virginia put-and-take streams were stocked with 150 and 50 of each strain in March and May, respectively. Creel and electrofishing surveys were conducted to determine harvest, movement and survival after fishing. A reference (unfished) stream was also selected and stocked with 50 of each strain, and electrofishing surveys were conducted to determine survival, growth and movement. SW and EN strains were caught by anglers primarily during opening weekend (April 4-5, 1981), while the FL and SC strains were caught throughout the creel survey period. The MC strain was consistently lowest for total estimated harvest, while the SC and SW strains were equally high in total estimated harvest. Significant differences occurred in the proportional relationships of strain harvests among streams. May harvest results generally corroborated April results, except that significant differences among streams were not found. Greater survival for strains with low harvests during April was not evident in fished streams. Natural mortality rates in the reference stream did not differ significantly among strains between May 20 and October 22, 1981. Change in average length of the strains over four months in Spring Branch ranged from -4.3 mm for EN to +18.9 mm for SW. Percentage of stocked biomass of the SW strain remaining after five months (20.8%) in the reference stream was more than twice that remaining for the EN (9.6%) and SC (9.4%) strains. No significant differences in downstream movement, and no significant upstream movements, were observed for strains in the fished and reference streams. / Master of Science

Thesis (MPhil)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: trout was conducted at the Jonkershoek trout research station of the Division of Aquaculture, University of Stellenbosch. Treatments consisted of ten experimental diets containing increasing levels of Spirulina (0%, 0.05%, 0.1%, 0.15%, 0.3%, 0.6%, 1.25%, 2.5%, 5% and 10%). The data was analyzed through means of a one-way ANOVA and Tukey’s pair wise comparison test for significant differences between treatments for the various parameters of flesh pigmentation and growth. The results indicates that the inclusion of Spirulina in the diets of rainbow trout will cause a undesirable yellowing of fillets, particularly at levels of inclusion at 5 percent and above, which may limit its use in diets for rainbow trout. There was an inconsistent increase in b* (yellowblue) and Chroma values with increasing levels of Spirulina inclusion, which may indicate the deposition of carotenoids (yellow-orange colour range) instead of the desired deposition of xanthophylls (pink-red colour range) in the flesh of the rainbow trout. This increase in b* (yellow-blue) values was significantly higher (P<0.05) at inclusion levels above 5 percent. Spirulina had no significant effect on weight gain of rainbow trout at any level of inclusion. No significant differences (P>0.05) were observed in any of the other production performance parameters (growth rate, feed intake, feed conversion ratio, viscerosomatic index, hepatosomatic index, and liver lipid content) that were evaluated. Low mortality rates were observed with no significant differences between treatments. A trend of decreased feed intake with increased levels of Spirulina inclusion became significant at the 2.5 percent level of inclusion, caused by deterioration in the palatability of the feed. A significantly higher dress-out percentage was observed at levels of Spirulina inclusion above 5 percent. A trend of decreased liver lipid content with increased Spirulina inclusion was observed, though not significant at any level of Spirulina inclusion. This observation justifies further investigation because of its potential to improved carbohydrate metabolism in carnivorous fish Results confirm that up to 10% Spirulina can effectively replaced soybean meal in the control diets for rainbow trout while simultaneously improving carcass dress-out at high inclusion levels. / AFRIKAANSE OPSOMMING: rantsoen van reënboog forel te evalueer. Die eksperiment is opgestel by die Akwakultuur Divisie, van die Universiteit van Stellenbosch, se navorsingstelsel in Jonkershoek, buite Stellenbosch. Reënboog forel (Oncorhynchus mykiss) vingerlinge van gemiddeld 20 gram is gebruik en ingedeel in 20 ronde tenks volgens kommersieële digthede (250 per tenk). Die rantsoene is gemeng met verskeie vlakke van Spirulina insluiting (0%, 0.05%, 0.1%, 0.15%, 0.3%, 0.6%, 1.25%, 2.5%, 5% en 10%). Twee herhalings van elke rantsoen is gevolg vir ‘n periode van 3 maande. Die vis is ad lib (volgens behoefte) gevoer, drie maal per dag. Daar was ‘n neiging tot ‘n verhoging in b* (geel-blou) en Chroma waardes met verhoogde insluitingsvlakke van Spirulina. Hierdie is wel ‘n aanduiding van die deponeering van karoteen, maar val in die geel-oranje kleur reeks en is nie die verlangde pienk-rooi (xantofil) kleur in die spier weefsel van die vis nie. Die verhoging in b* (geel-blou) waardes was statisties betekenisvol (P<0.05) bo die 5% insluitings vlak. In vergelyking met die kontrole (0%) rantsoen, was daar geen betekenisvolle massa toename na afloop van die proef tussen die verskeie behandelings nie. Behalwe vir ‘n verskil in voer inname, was daar geen statisties betekenisvolle verskil (P>0.05) waarneembaar tussen die verskillende behandelings ten opsigte van die verskeie produksie prestasie parameters nie. Daar was wel ‘n afnemende neiging in voer inname met verhoogde vlakke van Spirulina wat betekenisvol geraak het bo 2.5% insluitingsvlak. Smaaklikheid kan die moontlike rede hiervoor wees. Baie lae mortaliteite is ervaar by al die insluitings vlakke. Daar was ook ‘n neiging in hoër uitslag persentasie by verhoogde insluitingsvlakke van Spirulina wat betekenisvol geraak het bo 5 % insluiting. ‘n Afnemende vlak van lewer lipied inhoud is waargeneem maar was nie betekenisvol by enige van die insluitingsvlakke nie. Resultate van die proef dui daarop dat 10% Spirulina insluiting effektief kan dien as ‘n gedeeltelike plaasvervanger vir soyaboon meel in forel rantsoene. Die hoër uitslag persentasies hou belofte in. Die onverlangde vergeeling van die filette mag die gebruik van Spirulina beperk by reënboog forel rantsoene veral bo 5 % insluitings vlakke. Die verlaging in lewer lipied vlakke by ‘n verhoging van Spirulina insluiting regverdig vêrdere navorsing oor die potensiaal van Spirulina om die metabolisme van koolhidrate te verbeter by karnivoor visspesies.

An investigation of the genetic and meristic patterns of coastal cutthroat trout (Oncorhynchus clarki clarki) in two coastal basins, one in Oregon and one in Alaska, revealed varying degrees of differences among populations within each site. Coastal cutthroat trout collected from seven sites above and below barriers from Elk River, Oregon were characterized by significant genetic structuring (Fst=0.095) based on allozymes and significant differences among nine meristic characters. This may reflect the geologic history and local conditions of the Elk River Basin. Despite this divergence, Elk River populations were relatively similar to each other (Nei's genetic identity> 0.0987), suggesting that these populations share common ancestry. Fewer differences were detected among the coastal cutthroat trout from four sites below and above a barrier within Vixen Inlet, Alaska. Genetic structuring among populations was low (Fst=0.016) and significant differences were detected in only two of nine meristic characters. This may reflect the recent glacial history of southeast Alaska. In both sites, there was concordance between allozyme data and meristic data. / Graduation date: 1996

Indole-3-carbinol (I3C) inhibits chemically induced tumor formation in rodents and rainbow trout. This study examines the effect of I3C and its analog, indole-3-acetonitrile (I3N) on xenobiotic-metabolizing enzyme systems. The modulation of these enzyme systems have been shown to have significant effects on the interaction of chemical carcinogens and cellular constituents. Rainbow trout were fed 500, 1000 and 2000 ppm dietary levels of I3C and 50, 500 and 1000 ppm dietary levels of I3N for 8 days. β-napthoflavone (BNF), which is also an effective anticarcinogen in the trout, was fed at a 500 ppm dietary level and was used as a positive LM4b (a cytochrome P-450 isozyme) inducing control. Enzyme activities assayed were: ethoxyresorufin-O-deethylase (EROD), ethoxycoumarin-O-deethylase (ECOD), glutathione S-transferase (GST), and uridine diphosphoglucuronosyl transferase (UDPGT). Total cytochrome P-450 content was determined spectrophotometrically by the CO reduced method. The specific P-450 isozymes, LM2 and LM4b, were detected quantitatively using the western blot method. The BNF diet induced EROD and ECOD activities by an average of 17 fold and 5.5 fold, respectively. Total P-450 content was increased 2-fold; the P-450 isozyme LM4b was induced more than 5-fold, but LM2 content remained unchanged. This diet increased UDPGT activity 1.5-2-fold, but GST activity was not induced by dietary BNF. Neither I3C nor I3N induced the activity levels of the enzymes assayed at any administered dietary levels, which have previously shown to inhibit tumor formation and reduce formation of carcinogen-DNA adducts. Thus, the anticarcinogenic mechanism of I3C may proceed in trout by mechanisms other than enzyme induction. Further experiments on the effect of I3C and I3C acid condensation products (RXN) on in vitro AFB1-DNA binding resulted in a 40% and 48% inhibition of AFB1-DNA binding by I3C and RXN, respectively. Additions of RXN at levels much lower than those estimated to exist in vivo in hepatic tissue resulted in a significant reduction in AFB1-DNA formation suggesting that even small levels of RXN offers protection against the genotoxic effect of AFB1. However, in vitro additions of neither I3C nor RXN had an effect on DNA binding using AFBI-CI₂, an aflatoxin analog that does not require enzymatic activation. These results suggest that the primary mechanism for I3C inhibition of AFB1 induced carcinogenesis may proceed by inhibiton of formation of the ultimate electrophile, i.e. by reversible inhibition of cytochrome P-450. / Graduation date: 1989

The hypothesis that Arizona and brown trout regulate their numbers through the emigration of all individuals that are in excess of resources was tested experimentally. Different amounts of food and cover were provided to mixed sizes of trout in artificial stream channels with escape routes. The number of both species of trout that became resident generally varied in direct proportion to the amount of cover present; the numbers that established residency in either species stabilized in response to cover levels within 6 days. Emigratory behavior was much slower in response to food than to cover. The smallest Arizona trout showed the greatest decrease in numbers that established residency after being starved for 10 days; however they did not increase their numbers when food was increased above 30 g/day. Arizona trout over 14 cm SL and brown trout over 11 cm SL showed no change in the number of residents whether they were fed or starved for 69 days. There were consistent numbers of both species within 2 cm size intervals that became resident, suggesting that each size class independently regulates its numbers to its own resources. The small inter-replicate variance in numbers of trout that became resident at different levels of resources supports the hypothesis that Arizona and brown trout use emigration as a behavioral mechanism for self-regulation of numbers. The numbers of trout that became resident in channels with coexisting species were close to those observed in single species tests wherein resources were the same; immigrant brown trout were able to induce emigration in resident Arizona trout whereas immigrant Arizona trout seldom displaced resident brown trout. Therefore, theories concerning self-regulation of population numbers should be expanded to include an interspecific mechanism. Management practices such as stocking programs, habitat manipulation and multi-species fisheries can be ineffective unless the ramifications of population regulation are included in their design.

No description available.

Nanotechnology is a rapidly growing industry of global economic importance, with new technologies exploiting the novel characteristics of materials manufactured at the nanoscale being developed for use within the biomedical, electronic, energy production and environmental sectors. The unusual properties of engineered nanomaterials (ENMs) that make them useful in such applications have led to concerns regarding their potential impact on the environment. The aquatic environment is particularly at risk of exposure to ENPs, yet, there is currently little known about their behaviour in aquatic systems, their capacity to be taken up by aquatic organisms or their potential toxic effects. The studies that were conducted during this work sought to investigate the ecotoxicology of a range of metal and metal oxide nanoparticles using fish as a vertebrate model. In order to gain a better understanding of the uptake and effects of ENMs in fish, rainbow trout (Oncorhynchus mykiss) were exposed to nanoparticulate (34 nm) and bulk (>100 nm) titanium dioxide particles via the water column (500 and 5000 µg L-1), and to titanium dioxide nanoparticles via the diet (0.1 and 1 mg g-1 food) and via intravenous injection (1.3 mg kg-1 body weight). Uptake of titanium dioxide into the tissues of trout after waterborne and dietary exposure was found to be very low, suggesting limited bioavailability of the nanoparticles to the fish, although small amounts of uptake of titanium dioxide across the gill epithelial membrane were observed using coherent anti-stokes Raman scattering. Intravenously injected titanium dioxide accumulated and was retained in the kidneys for up to 21 days, but no adverse effect on kidney function was detected. Silver nanoparticles are already in widespread use in a variety of consumer products such as wound dressings, food containers, sock fabrics and paints, principally for their antimicrobial activity. Despite its growing commercialisation, there is little known about the environmental effects of the use of nanoparticulate silver in these products. In order to investigate these potential effects, rainbow trout were also exposed to 10 nm, 35 nm and bulk (0.6-1.6 µm) silver particles via the water column at concentration of 10 and 100 µg L-1. Uptake of silver in the gills and liver of trout occurred, with smaller nanoparticles showing a greater propensity for association with gill tissue, but with no significant differences in uptake between particles of different sizes in the liver. No increases in lipid peroxidation were detected in gills, liver or blood plasma of trout, however, expression of cyp1a2 was significantly up-regulated in exposures to 10 nm silver particles in the gill, suggesting an increase in oxidative metabolism. In an attempt to develop an effective high through-put in vitro screening assay for ENMs, the suitability of isolated rainbow trout primary hepatocytes was examined as a potential model for in vitro screening of a range of toxicological endpoints in response to nanoparticles and for studying uptake of nanoparticles into cells. The hepatocytes retained a good level of functionality after culturing as evidenced by vitellogenin production in response to the synthetic oestrogen, 17β-oestradiol. The cultured hepatocytes, however, showed limited responses on exposure to titanium dioxide, zinc oxide, cerium oxide and silver nanoparticles for lipid peroxidation and glutathione-s-transferase activity assays. Furthermore, the hepatocytes were unresponsive to the induction of these biological responses in the positive controls, suggesting they are not a good model for investigating the potential toxic effects of ENMs in terms of these endpoints. Uptake of the nanoparticles into the cells, however, was demonstrated by coherent anti-stokes Raman spectroscopy, indicating that this in vitro assay may provide a useful model for studying uptake of ENPs into cells. The studies conducted in this thesis contribute the science base regarding the bioavailability of ENPs in aquatic media as well as highlighting the importance of characterisation of ENPs in understanding their behaviour, uptake and effects in aquatic systems and in fish.

This study sampled salmonid populations in two headwater streams in East Tennessee, Briar Creek and Left Prong Hampton Creek. Length and weight data were used to calculate the growth of these populations to determine if significant variation exists between isolated brook trout populations. Slope comparisons concluded that there was a difference in growth between brook trout populations of these streams (p