The relationships between brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), non-game fish populations and selected physical and chemical parameters were investigated in four streams draining the Blue Ridge Mountains in north-central Virginia during low flow conditions in August, 1981 and 1982. Multiple regression and discriminant function analysis identified average stream width and maximum stream temperature as the main environmental factors related to brook and brown trout abundance and distribution. Furthermore, consistent fish species assemblages relative to brown trout distribution were observed in the study streams. The movements of tagged brown trout in two streams were assessed for the period from June 1981 to July 1982. Most brown trout remained within 200 m of original tagging sections, 98.7% in the Conway River (78 out of 79) and 71.4% in the North Fork Thornton River (7 out of 9). The 1979, 1978 and 1977 year class fish (ages 2+, 3+ and 4+) exhibited extremely restricted movements and were invariably recaptured at original capture locations while the 1980 year class (age 1+) displayed small net upstream movements (<80 m) throughout the period. Two 1980 year class individuals displayed extensive movements (17.0 km downstream and 1.2 km upstream). These movements were characteristic of other stream resident brown trout populations. Results of this study suggest that brown trout may expand their range upstream into currently allopatric brook trout zones. It would likely be a slow but steady process which could be accelerated by infrequent long-range movements. The potential for establishment of reproducing brown trout populations and impacts of brown trout on native brook trout populations can be assessed utilizing fish species assemblages, average stream width and maximum stream temperature prior to further brown trout introductions in this region of Virginia. / Master of Science

Dissertation (PhD (Agric))--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: A breeding programme aimed at the genetic improvement of growth rate of rainbow trout was initiated in 1988 by the Department of Genetics, University of Stellenbosch, in collaboration with the local trout producer's organisations. The first phase of the breeding programme included the collection, evaluation and selection of the best available genetic material from 13 different genetic groups (nine local and four overseas) to make up two separate base populations as odd and even year-groups. This was done to establishment a base population with high genetic merit and variation at the onset of the breeding programme. Statistically significant and commercially valuable genetic differences in terms of weight and length gain were detected between the various hatchery groups. The next two generations of the breeding program included a series of single and double crosses in order to increase the levels of genetic variation in the base populations, and to investigate possible heterosis and specific and general combining ability among the crosses. Significant levels of heterosis (6.7% to 9.6%) and general combining ability was found for weight and length gain during consecutive growth stages. No evidence was found for specific combining ability among the crosses. The crossing of selected offspring from the original genetic groups followed by the application of intensive multi-stage selection for growth rate within progeny groups has led to the establishment of second and third generation parental populations with higher levels of genetic variation and improved individual genetic merit with regard to growth rate. The exploitation of non-additive genetic variation within the base populations through crossbreeding and heterosis during the early stages of the selection programme was delayed in favour of the utilization of additive genetic variance through a procedure of multi-stage selection that incorporated high intensities of selection within and between family groups. The estimation of genetic parameters during the fourth generation on the basis of a hierarchical half-sib family structure confirmed the presence of high levels of additive genetic variation within the respective populations/year-groups. High heritability values in the range of 0.40 to 0.53 were recorded for body weight and length at 150 days. Genetic correlations between the traits were also high, in the range of 0.74 to 0.82. The cumulative realized response of 50% in body length for the EVEN year-group after six generations of selection (8.3% per generation), and the 33% for the ODD year-group after five generations of selection (6.6% per generation) confirms the efficiency of the multi-stage selection procedure to exploit the available additive genetic variation for growth rate within the respective populations. The programme is still ongoing, entering its 7th generation in 2004 and is supplying about 50-60% of commercial material through direct supplies of broodstock, ova and fingerlings and indirect supplies via multiplier stations (commercial hatcheries). The programme was the first of its kind in relation to aquaculture species in the Southern African region, and has since initiated the introduction of programmes of genetic improvement in three other indigenous species, namely tilapia (Oreochromis mossambicus), African catfish (Clarias gariepinus) and abalone (Haliotis midae). / AFRIKAANSE OPSOMMING: ‘n Teelprogram gerig op die verbetering van groeitempo in reënboogforel is in 1988 ingestel onder toesig van die Departement Genetika aan die Universiteit van Stellenbosch, in sameweking met die plaaslike forelprodusenteverenigings. Die eerste fase van die teelprogram behels die versameling, evalasie en seleksie van die beste beskikbare genetiese materiaal vanuit, 13 verskillende genetiese groepe (nege plaaslike en vier van oorsee) om twee basispopulasies te ontwikkel in elk van die gelyke en ongelyke jaargange. Die doel daarvan was om ’n basispopulasie met hoë genetiese meriete en variasie te ontwikkel met die aanvang van die teelprogram gerig op genetiese verbetering, deur middel van seleksie. Statisties betekenisvolle en ekonomies belangrike genetiese verskille in massa- en lengtetoename is aangetref, tussen die onderskeie genetiese groepe. Die daaropvolgende twee generasies binne die teelprogram behels die uitvoering van ’n reeks enkel- en dubbelkruisings ten einde ’n verdere toename in genetiese variasie in die basispopulasies te bewerkstellig, sowel as om die voorkoms van heterose en algemene, sowel as spesifieke kombinerings-vermoë tussen die kruisings te bepaal. Betekenisvolle vlakke van heterose (6.7% tot 9.6%) sowel as algemene kombineringsvermoë, is aangetref ten opsigte van massa- en lengtetoename in opeenvolgende groeifases. Daar kon geen aanduiding van betekenisvolle, spesifieke kombineringsvermoë gevind word nie. Die kruising van geselekteerde nageslag vanuit die oorspronklike genetiese groepe, gevolg deur ‘n multi-fase seleksiemetode vir groeitempo binne nageslaggroepe, het bygedra tot die ontwikkeling van ‘n tweede en derde generasie broeipopulasie wat beskik oor hoër vlakke van genetiese variasie en verbeterde individuele meriete ten opsigte van groeitempo. Die benutting van nie-additatiewe genetiese variasie binne die basispopulasies deur middel van kruisteling en heterose tydens die vroee stadium van die teelprogram is uitgestel ten gunste van die benutting van additatiewe genetiese variasie deur middel van ‘n multi-fase seleksiemetode, wat berus het op die toepassing van hoë vlakke van seleksie-intensteit binne en tussen familiegroepe. Die beraming van genetiese parameters tydens die vierde generasie het die voorkoms van hoe vlakke van additatiewe variasie binne die onderskeie jaargroepe bevestig. Hoë oorerflikhede van 0.40 tot 0.53 is beraam vir ligaamsmassa en -lengte op die ouderdom van 150 dae. Genetiese korrelasies tussen die kenmerke was ook hoog met waardes van 0.74 tot 0.82. Die saamgestelde gerealiseerde seleksierespons van 50% vir liggaamslengte vir die “EVEN”-jaargroep na afloop van ses generasies van seleksie (8.3% per generasie) en die 33% van die “ODD”-jaargroep na afloop van vyf generasies van seleksie (6.6% per generasie) het die doeltreffendheid van die multi-fase seleksiemetode bevestig ten opsigte van die benutting van die additatiewe variasie vir groeitempo binne die onderskeie basispopulasies/jaargroepe. Die teelprogram duur steeds voort en sal die 7de generasie in 2004 bereik. Die program voorsien nagenoeg 50-60% van die kommersiele materiaal vanuit direkte voorsiening van teelmaterial, eiers en vingerlinge asook die indirekte voorsiening via kommersiële teelstasies. Die teelprogram was die eerste van sy soort met betrekking tot akwakultuurspesies in Suider Afrika en het bygedra tot die implimentering van programme van genetiese verbetering in drie inheemse spesies, naamlik die tilapia (Oreochromis mossambicus), die baber (Clarias gariepinus) en die perlemoen (Haliotis midae).

For many native, imperiled salmonid species, the prioritization of recovery and conservation efforts hinges upon the identification of a species most limiting life stage. The early life-history stage can be a limiting life stage for fish, and given the importance of the reproductive stage to overall persistence, there is a need to better understand the spawning ecology and early life history of many salmonids. The Logan River, in northern Utah, contains one of the largest metapopulations of imperiled Bonneville cutthroat trout (BCT) throughout the Bonneville Basin. Little research has evaluated the temporal and spatial distribution of BCT spawning nor quantified their early life-history survival. In the summer of 2008, I documented the spawning ecology of BCT and quantified their early life-history survival via egg-to-fry survival field experiments in four tributaries to the Logan River. I observed considerable variability in the timing, magnitude, and duration of spawning between study streams, in part as a function of a variable, multi-peaked hydrograph. I also conducted egg-to-fry survival experiments using incubation boxes and hatchery-fertilized, eyed cutthroat embryos and installed these boxes throughout my study streams. I found that survival was extremely variable within and among my study streams. For example, the variation I observed in survival appeared to be a function of fine sediment loads. Lastly, I observed that in the Logan River the timing of greatest intensity of both stream side and in-stream anthropogenic activities (e.g., livestock grazing, horseback riding) overlaps directly with the spawning and early life stages of BCT. Using my estimates of early survival, I revised a four-stage matrix population model for BCT in order to evaluate the hypothetical effects of anthropogenic impact on rearing areas. I determined that population growth rates are sensitive to perturbation at the egg-to-fry and fry to age-1 stages, and if even a small number of redds are destroyed through habitat degradation, a high degree of immigration of reproductively mature BCT is required to maintain the near-term persistence of this population. Future conservation efforts for BCT should be prioritized to protect areas where land-use activities are high during the sensitive spawning and early life-stage periods.

No description available.

Lake Moomaw, a 1024 ha flood control reservoir in western Virginia, retains sufficient cold, oxygenated water (< 21°C, ≥ 5.0 mg/L) to allow trout survival throughout most of the summer. However, trout habitat declines to an annual minimum in September. vertical gillnets and ultrasonic telemetry were used to determine the horizontal and vertical distribution of two cohorts of brown trout, <i>Salmo trutta</i>, and rainbow trout, <i>Oncorhynchus mykiss</i>, relative to ambient temperature and dissolved oxygen. Capture of trout in gillnets afforded the assessment of condition (K), relative liver weight (HSI), and daily consumption (CD) of age 1+ brown and rainbow trout in relation to habitat dynamics. Most age 1+ brown and rainbow trout were distributed in the metalimnion (12 - 21°C) from July to October, even when dissolved oxygen declined below 5.0 mg/L. Location in the metalimnion placed young trout near optimum temperatures and maximum prey abundance. The growth, condition, relative liver weight, and daily consumption of age 1+ brown and rainbow trout were apparently unaffected by habitat limitations. Age 1+ brown trout preyed almost exclusively on alewives, <i>Alosa pseudoharenqus</i>, whereas aquatic and terrestrial insects constituted a substantial portion of young rainbow trout diet. Age 2+ rainbow trout were distributed in the metalimnion from July to September, but were located in the hypolimnion (<12°C) in October. Adult brown trout were located in the metalimnion during July, but were distributed in the hypolimnion from August to October. Adult trout in the hypolimnion were at low temperature (10°C) and diminished dissolved oxygen concentrations (<5.0 mg/L). Distribution in the hypolimnion also resulted in isolation from primary forage alewives. Age 2+ brown trout effectively were not feeding, as only one of 16 adult brown trout collected in two years of sampling contained food. Adult rainbow trout consumed primarily alewives in August and aquatic insects in September, but were apparently not feeding in October. Small sample size precluded the direct measurement of the effects of this isolation on the growth of age 2+ trout in Lake Moomaw. A bioenergetics model predicted that even brief durations of isolation from prey could severely limit the growth of age 2+ brown and rainbow trout. / Master of Science

Restored docks have high amenity, tourism and recreational value. Polluted and unaestheticw ater is a major factor potentially inhibiting redevelopmento f docklands, particularly if the source of water suffers from severe pollution problems. The aims were to examine spatial and temporal patterns of hydrography and ecology of Merseyside Docks. Strategies to develop benthic filter-feeders on both the walls and in the sediments were considered important in maintaining good water quality. In the South Docks, algal blooms were mainly small and short-lived and anoxia was infrequent. In Princes Dock (Central chain) water quality was very good. Morpeth Dock (Wirral chain) suffered from poor water quality. Anoxia resulted in high mortalities of dock fauna and fish and the release of hydrogen sulphide gas. Algal blooms were very large and were maintained over long periods. The dinoflagellate, Prorocentrum minimum, was particularly prevalent. Zooplankton have remained at relatively low densities in the South Docks, particularly in Albert Dock (South chain), probably because of strong competition for food with benthic filter-feeders. In contrast, Morpeth Dock has maintained much higher numbers, probably because of the plentiful food supply and absence of benthos. The benthos of the walls was surveyed. Mytilus edulis is most prominent in Albert and Queens Docks; Ciona intestinalis and Ascidiella aspera are most abundant in Albert and Princes Docks; and, Molgula manhattensis dominant in Brunswick and QueensD ocks. Tiles have been used to follow the pattern of annual successiona nd the effect of timing of available space on this pattern of succession. In contrast to previous years when there had been very little recruitment of Mytilus to the South Docks, Mytilus settlement occurred in Queens Dock during autumn 1995. Experiments aimed at increasing the filter-feeding capacity by introducing Cerastodermae dule (common cockle) and manipulating particle size of the sediment concluded that cockles do not survive in the dock, probably due to occasional low oxygenc on centrations in the hypolimnion, and modification of sediment has very little effect on natural colonization. Experiments examined the impact of filter-feeders on phytoplankton numbers and regeneration of nutrients. Mytilus was shown to have higher clearancer ates( cell mV h' int) than its major competitors( Ciona intestinalis, Styela plicata) on the dock wall. The experiment investigating nutrient release by Mytilus indicates release of phosphate. Fish communities in the South Docks were relatively diverse, with a total of fifteen species of fish being caught. The size/frequency analyses suggest that the majority of fish were juveniles. The occurrence of two sea trout (Salmo trutta) indicates a return of salmonids to the estuary. The use of a capacity model as a management tool is proposed; this has been fitted to the South Docks system with some success.

Selenium is an important nutritional element that is required in a minute amount for maintenance of proper health in both humans and animals. Many biochemical processes in human and animal depends on Se and selenoprotein function, and various studies have suggested that Se supplementation can improve fundamental immune function in both humans and animals. Se status in the UK is very low; therefore, there is a need to enhance selenium intake through diet. One way of doing that is through the introduction of selenium to farmed animals. In this Ph.D. study, we fed rainbow trout with diet containing different spiked concentrations (0.8 - 8.9 μg g-1) of Se for 14 weeks. Fish were sampled every two weeks and liver, kidney, muscle, gills and whole blood were collected and processed. The first phase of this Ph.D. study focused on selenium distribution and biotransformation in tissues of rainbow trout. Three methods were developed and used to determine total selenium concentration; species' distributions in tissues and Se peptide sequence to determine the possible incorporation of Se into proteins respectively. In the first method total selenium concentration was determined using ICP-MS and the second and third methods using HPLC-ICP-MS/ESI-MS. Total selenium concentrations in trout tissues were determined, and the highest selenium concentrations were found in liver followed by kidney, gills, and muscle. SeMet and SeCys were found to be the major species in all tissues followed by inorganic and other unknown species. To determine the possibility of Se incorporation in to protein, peptide de novo sequencing was carried out. Few selenoprotein were identified using automated de novo sequence and database search. Se species distributions in tissues of beached Pilot whales were studied. Several low molecular weights Se species were identified with selenite pre-dominating other species in most of the adult whales tissues analysed.

The nutritional and chemical characteristics of five earthworm species: Lumbricus terrestris; Allolobophora longa; Eisenia foetida; Dendrobaena veneta and Dendrodrilus subrubicundus were assessed on the basis of crude protein and amino acid composition, lipid and fatty acid composition, and ash and mineral composition. Analyses indicated that all the earthworm species evaluated possessed a high quality protein and lipid fraction suitable for use in fish feeds which was somewhat similar in composition to that of fish meal. During experimental feeding trials (50-84 days in duration) each earthworm species was nutritionally evaluated, on the basis of fish growth performance, feed utilization efficiency and gross carcass composition, as a complete feed (frozen slices of whole worm) for rainbow trout· (Salmo gairdneri) A dried 'earthw9rm meal' derived from each of the species E.foetida, D.veneta and D.subrubicundus was similarly evaluated as a potential replacement for fish meal in trout diets. Fish fed frozen slices of earthworm, with the exception of fish fed E.foetida, achieved growth rates and feed utilization efficiency comparable to. fish fed a control, fish meal based ration. Fish fed solely on frozen slices of E.foetida achieved little or no growth over the experimental period. The possible reasons for the reduced palatability of frozen E.foetida to the fish are discussed, pre-treatment processes applied and a significant improvement in the palatability of frozen E.foetida was achieved by blanching. High dietary inclusion levels of earthworm meal (replacing ~ 50% of the fish meal protein) resulted in depressed feed intake and growth of the fish. At reduced levels of inclusion, dried E.foetida meal (constituting 5-30% of a production salmonid diet) and dried D.subrubicundus meal (constituting 7-36% o~ a semi-synthetic trout diet) adequately replaced the dietary fish meal component without loss in fish growth and feed utilization efficiency. The possible uptake of potentially toxic trace elemeots (Fe, Zn, Mn, Pb, Cu, Cr, Ni, Co and Cd) into the fish carcass through the ingestion of contaminated earthworm diets was also investigated and the levels of certain elements, in particular Pb, were observed to increase in the carcass of fish fed high levels of earthworm in the diet. However, in no instance did the results indicate any harmful or toxic effect of including earthworms in the diets of rainbow trout.

Current riparian management objectives in the Pacific Northwest promote both retention of existing conifers and conversion of hardwood-dominated areas to conifers. Although understanding of relationships between riparian vegetation and salmonid prey availability is growing, temporal variation in these relationships is poorly understood. Seasonal fluxes in availability of aquatic and terrestrial invertebrate prey for coastal cutthroat trout (Oncorhynchus clarki clarki) were investigated by estimating invertebrate biomass from aquatic (benthos and drift) and allochthonous (terrestrial) sources in three watersheds in the Oregon Coast Range. To investigate the influence of vegetation type on food sources, samples were collected in each watershed from stream sections dominated by deciduous, conifer, and mixed vegetation. During each sample period, diet was assessed by examining gut contents of captured trout. Stream discharge appeared to be an influential factor regulating seasonal fluxes of aquatic invertebrate biomass in the benthos and drift. Total allochthonous invertebrate biomass at deciduous and mixed vegetation sites (64 and 61 mg·m⁻²·day⁻¹, respectively) was almost 30% higher than at coniferous sites (45 mg·m⁻²·day⁻¹). Although aquatic insects dominated the total gut contents during this study, prey from terrestrial origin was more common during summer and fall. These results suggest that systematic removal of deciduous vegetation in riparian zones to promote conifers may have unintended consequences on the food resources of coastal cutthroat trout and the productivity of aquatic food webs in the Pacific Northwest. / Graduation date: 2004

The effects of different dietary lipids on the growth, nutrition and tissue lipid profiles of rainbow trout raised to market size on a commercially available ration were examined. Rainbow trout of 80 g mean initial weight were fed pellets prepared according to Oregon Moist Pellet specifications for 20 weeks. Salmon oil (0MP-1), soybean oil (OMP-2), linseed oil (OMP-3), chicken fat (OMP-4), pork lard (OMP-5) and beef tallow (OMP-6) were used for the 6% lipid component of the diets. No differences in feed conversion or growth rate were observed across diet groups. Trout nutrition was monitored by three blood parameters -- red blood cell (RBC) fragility (hemolysis), packed cell volume (PCV) (hematocrit), and percent hemoglobin. The OMP-1 diet appeared to have caused oxidative stress in trout as measured by hemolysis, while hematocrit and percent hemoglobin values were uniform across diet groups. Tissue levels of total n-3 fatty acids were highest in the OMP-3 group and decreased in the order OMP-1 > OMP-2 = OMP-4 = OMP-5 = OMP-6. However, unaltered linolenic acid (18:3 n-3) comprised almost 50% of the n-3 fatty acid content of OMP-3 trout tissue lipid. The level of total 20:5 n-3 plus 22:6 n-3 (18%), was 33% higher in tissue from OMP-1 trout than tissue from all other diet groups which held fairly constant at 12% across OMP groups 3-6. The lowest tissue level of total 20:5 n-3 plus 22:6 n-3 was found in the OMP-2 trout, 10%. Trout raised on the OMP-1 diet also retained higher tissue stores of 20 and 22 carbon monoenes than trout fed OMP diets 2-6, but less than dietary levels. In contrast, trout fed OMP diets 2-6 retained higher tissue levels of these same fatty acids than dietary levels. The diet ratio of polyunsaturated fatty acids (PUFA)/22:1 appeared to influence whether 22:1 was conserved or oxidized. The most favorable balance of trout tissue monoenes, n-6 fatty acids and total 20:5 n-3 plus 22:6 n-6 for human health was found in trout fed the OMP-6 diet. / Graduation date: 1988