Five groups of 400 hatchery rainbow trout, (Salmo gairdneri), were stocked in a small, mountain stream at )-week intervals from June to September, 1972. A fish trap captured any fish moving out of a 500 m study section. Fish began moving at high levels during the first day of each stocking and continued at high rates for 5-8 days (Early Phase), after which movement decreased to low levels for 6-9 days (Late Phase). Early Phase fish moved primarily at night, possibly due to their disoriented state and high subjectivity to stream conditions. Fish moving during Late Phase did so mainly during daylight, probably in response to diurnal periodicity of a day-active food organism in the drift. Forced movement due to social behavior did not seem to be an influencing factor, but the duration of visible light seemed important to moving fish.

<p>Teleosts take up metals by two major pathways: gills and/or gut. Past research is heavily focused on branchial uptake despite evidence that the gastro-intestinal tract (GIT) is the dominant route in some natural environments. To address this information gap, my thesis characterizes uptake mechanisms of Cd and Ca along the GIT of <em>Oncorhynchus mykiss</em>. Toxic effects of Cd, protective effects of Ca against Cd uptake, and Cd distribution within fish after ingestion are also explored.</p> <p>Four-week dietary Cd exposure affected growth and Ca regulation, while causing toxicity at the subcellular level. Elevated Ca in diets protected against accumulation and altered subcellular handling of Cd. Pre-exposure to different diets changed unidirectional uptake and binding rates of Cd and Ca, although they remained highly correlated. Binding rates of Cd to mucus can predict absorption rates of Cd<strong>.</strong></p> <p>A variety of <em>in vitro </em>and <em>in vivo </em>experiments on four distinct GIT segments (stomach, anterior-, mid-, and posterior- intestine) were undertaken to determine specific mechanisms of Cd and Ca uptake in freshwater trout. Cd transport was unaffected by solvent drag, but was stretch- and temperature- sensitive. Strong evidence for a common pathway for Ca and Cd transport was obtained. Cd also appeared to be taken up in part by zinc (ZIP-like) transporters and the divalent metal transporter DMT1. Ca uptake along the GIT appeared to be carrier-mediated, time- and concentration- dependent, but was not affected by solvent drag, or by Na concentration. Mucosal Cd did not inhibit Ca uptake. Ca, but not Cd, uptake rates were much lower in sea water-acclimated trout. Seawater and freshwater fish accumulated similar whole body Cd concentrations when fed contaminated diets for three weeks, but the majority of Cd in seawater trout remained in the posterior intestine tissue, while freshwater trout had higher internal burdens.</p> <p>This thesis advances the knowledge of metal uptake along the GIT of trout.</p> / Doctor of Science (PhD)

The activity of erythrocyte amino levulenic acid dehydratase (ALA-D) and liver and bone lead concentrations were measured in 141 wild rainbow trout from two highway-influenced and two pristine streams. A significant relationship between ALA-D activity and liver lead concentrations among streams (r = 0.157) was observed. However, this relationship was opposite of expected. Trout tissue lead and stream-water lead concentrations were lower than most concentrations observed for control laboratory trout. At these low tissue and water lead concentrations observed in the present study, ALA-D activity cannot be used to document exposure of fish to environmental lead. Other significant correlations with the activity of the enzyme included: trout length (r = -0.411); trout age (r = -0.385); and sediment lead (r = 0.093). Erythrocyte ALA-D activity significantly varied due to sampling period. However, reasons for this deviation cannot be explained from the present study. Multiple regression techniques revealed little concerning trout liver lead concentrations and ALA-D activity relationships. Like ALA-D activity, liver lead concentrations were deemed a poor indicator of organisms' exposure to environmental lead. Bone lead concentrations were the best indicator of environmental contamination. However, the best regression model, which regressed water lead on bone lead, explained only 20.6% of the variation in bone lead burden. In both roadside streams, water lead was positively correlated to turbidity and area precipitation. Water lead concentrations were also positively correlated to discharge in one roadside stream. / M.S.

In 2000 the European Union introduced the Water Framework Directive, new legislation that regulates the use of surface waters within the European Community. The goal of this legislation is to protect, enhance and restore all surface waters within the Community to Good Surface Water Status. Good-Status is described as having low levels of anthropogenic distortion in its hydro-morphological and physiochemical components as well as possessing biota that would normally be associated with the type-specific aquatic ecosystem. The assessment of ecosystem status is to be defined by comparisons with intact representative reference sites, by using modelling techniques that define reference conditions, a combination of the two, or expert judgement. As undisturbed aquatic ecosystems are rare or non-existent in Europe the base-line data will have to be defined using the latter methodologies. The aim of this project is to help define reference conditions for lotic systems in Europe based on the physical instream habitat parameters of a resident species. Brown trout (Salmo trutta), a ubiquitous and well studies species endemic to Europe, was used as the target organism to develop the assessment protocol. The project focused on the requirements this species has of aspects of its physical habitat; specifically, its usage of depth, velocity, and substrate. An extensive survey of the scientific literature was used to define the requirements trout has for the three physical parameters at four life stages. These are the spawning, nursery, juvenile and adult-resident life stages. These requirements were expressed as tolerance profiles, which defined suitable, usable and not-suitable habitat. The methodology was demonstrated by evaluating the physical habitat available at six reaches in three small streams, March, Burnhouse and Bin Burns, which drain into the Carron Valley Reservoir in central Scotland. From the perspective of water depth, these streams seem best suited as nursery areas, are less well suited as juvenile habitat, and do not appear to be well matched for adult residents. The assessment of both velocity and substrate indicated that the portion of the study reaches available for use by resident brown trout increased with trout size. The assessment of all three physical habitat parameters at all study reaches found variable portions of the streams suitable for use by spawning trout. When the habitat variables are integrated all stream segments streams seem best suited as nursery and spawning areas. To a lesser extent juvenile trout can use these burns and very little habitat is available for use by adult resident trout. The tolerance profiles that were created in this study are standardized assessment criteria that when compared with stream survey data can produce an appraisal of habitat availability in any fluvial freshwater system that supports populations of brown trout (Salmo trutta). The assessment method can be combined to produce an integrated habitat assessment, using both an index and by the calculation of Froude number, which is a more realistic approach than the assessment of individual habitat parameters as salmonids choose their microhabitat based on multiple factors. This approach allows an investigator to determine the amount and relative portion of useable habitat and to determine the quality of that habitat. Finally, by examining the physical habitat variable that most strongly correlates with the final integrated habitat distribution the individual habitat parameter that is most important to the distribution of physical habitat at a site can be determined. While this technique would certainly benefit from further development it does show potential to aid in physical habitat assessment of trout streams.

Ergasilus sieboldi has been reported from a number of trout fisheries in England and Wales. The population dynamics of this parasitic copepod in Rutland Water, a large reservoir in Central England was studied from 2003 to 2005. A combination of angler and net caught fish were examined to record numbers of adult females and egg production throughout each year. The parasite overwintered in large numbers on trout and commenced egg production in April which then continued until October/November. The prevalence of infection and the abundance of the parasite were very high in overwintered rainbow trout but these parameters then decreased in March as large numbers of uninfected fish were stocked into the reservoir. The parasite population then increased until October. Infection levels in 2004 and 2005 were significantly lower than in 2003. Infections of cage-held rainbow trout showed that E.sieboldi could become ovigerous within two weeks of attachment to trout in July and August. New infections occurred from June until November. Several species of coarse fish examined were also shown to be infected by the parasite. Cage trials showed that triploid rainbow trout were infected by significantly higher numbers of the parasite than diploid rainbow, brown trout or “blue” rainbow trout. Observations of infected fish in experimental tanks showed that overwintering parasites were stimulated to commence oviposition by increasing water temperatures. Photoperiod had no noticeable effect on the parasite. Egg viability and rate of development was studied using tank held infected fish and in vitro incubation techniques. Viability of eggs in sacs detached from the adult parasite was greater than those remaining attached. The rate of egg development was modelled and was shown to be predicted by temperature. Development of eggs was estimated to commence at 3.6ºC. Eggs developed more rapidly at higher temperatures and at peak production, inter-clutch interval was between 0 and 0.5 days. Egg production models estimated that an overwintered parasite could produce up to 19 clutches of eggs between April and October under normal temperature regimes measured at the reservoir. Ovarian development during the winter was confirmed using classifications of ovary size and shape based on parameters measured using image analysis techniques. The life span of E.sieboldi was estimated at 10-12 months. Nauplii culturing techniques were compared, and nauplii to stage V were successfully developed. Nauplii hatched from the eggs of adult parasites occurring in the spring were larger and conditioned to develop at lower temperatures than those hatched later in the year. Nauplii were fed on 4 different types of algae held in monocultures but development occurred only in algal polycultures. A comparison was made of nauplii feeding preferences and development with algae recorded in Rutland Water in 2003 and 2005 but no correlations were found. Fish stock assessment was carried out using models of angler catch, effort and stocking figures from the fishery. Parasite numbers on the overwintered fish were estimated at 12 million parasites in April 2003, 8.3 million in April 2004 and 1.2 million in April 2005. Stock assessments suggested a reduction in number of overwintering trout and effects of stocking policy to be at least partially responsible for the decline in the parasite population. The results of this study formed a management strategy for the operation of the trout fishery.

Selenium (Se) is an essential element, toxic at concentrations only slightly above those required. It can become detrimental to fish health when available in excess in the aquatic environment. This study examined the effects of Se on adult female rainbow trout, brook trout, and cutthroat trout fed Se-methionine for five months, and on their larvae. Differences between fish species and between tissues were observed in the accumulation of Se in adults, and dose-dependent effects of Se on plasma thyroid hormone concentrations in brook trout, gonad size in all three species, and indicators of oxidative stress in rainbow trout and cutthroat trout, were detected. Survival of larvae and swim-up success decreased with increasing egg Se concentrations in rainbow trout and cutthroat trout, however, the same effects were not observed in brook trout. Data from this study provide new evidence for species-specific Se accumulation and toxicity in salmonid fish. / xi, 123 leaves : ill. ; 29 cm

Stream living salmonids are generally regarded as drift feeders that rely upon their vision when foraging. It has been shown that salmonids become nocturnal at low water temperatures, but have a low foraging efficiency as light intensity is low, due to their dependence upon vision. Shifting from drift feeding to benthic feeding, has been suggested, and analyses of gut contents during winter have shown that the diet of salmonids mainly consists of benthic invertebrates. Most experimental studies of salmonid foraging have only offered the fish drifting prey or only given the fish access to benthic prey in total darkness. Such conditions rarely occur in nature and the importance of benthic foraging to salmonids may therefore have been underestimated. In this study I conducted a stream laboratory experiment to test if low light intensity caused juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) (age 0+) to forage more on benthic than drifting prey. The salmon foraged on both drifting and benthic prey during high light but consumed only benthic prey during low light (by one of six fish). Trout foraged on both drifting and benthic prey during both high and low light, but foraging efficiency was lower during low than high light and foraging efficiency was lower for benthic prey than for drifting prey. These results indicate that both species forage more opportunistically than previously thought. / Strömlevande laxfiskar anses generellt vara driftätare som förlitar sig på synen när de födosöker. Det har visats att laxfiskar blir nattaktiva vid låga vattentemperaturer, men har en låg födosökseffektivitet då ljusintensiteten är låg, på grund av sitt beroende av synen. Skifte från driftätande till att äta bentiska byten, har föreslagits, och analyser av maginnehåll under vintern har visat att laxfiskars diet huvudsakligen består av bentiska evertebrater. De flesta experimentella studier av laxfiskars födosök har endast erbjudit fisken driftande byten eller endast gett fisken tillgång till bentiska byten vid totalt mörker. Sådana förhållanden förekommer sällan i naturen och betydelsen av bentiskt födosök för laxfiskar kan därför ha underskattats. I den här studien utförde jag ett experiment i en laboratorieström för att testa om låg ljusintensitet fick juvenil Atlantlax (Salmo salar) och öring (Salmo trutta) (ålder 0+) att födosöka mer på bentiska än driftande byten. Laxen födosökte på både driftande och bentiska byten vid högt ljus men bara bentiska byten åts vid lågt ljus (av en av sex fiskar). Öringen födosökte på både driftande och bentiska byten vid både hög och låg ljusintensitet, men födosökseffektiviteten var lägre vid låg än hög ljusintensitet och födosökseffektiviteten var lägre för bentiska än förbiflytande byten. Dessa resultat indikerar att båda arterna födosöker mer opportunistiskt än vad man tidigare ansett.

This study examines three possible methods for improving the digestibility and bioavailability of zinc to rainbow trout (Oncorhynchus mikiss). The first method was to examine the availability of the zinc utilisation from commonly used protein sources; the second was to assess the efficacy of the upstream use of an enzyme treatment of the raw materials; the third was to assess the use of organically complexed mineral supplements as opposed to the inorganic salts widely used at present. The first section indicated that the zinc from the soyabean meal was the most available (49.4%). The zinc digestibilities of the animal based protein used in this current study were 15.1% for LT94 fish meal, 26.6% for the Provimi 66 white fishmeal and 15.8% for poultry meat meal. The zinc in the maize/corn gluten meal was 31.9% digestible and from the NuPro 26.1%. Gram for gram maize gluten meal supplied the least amount of zinc to the fish (3.66 mg per kg). Based on these results the diets for the subsequent supplementation trials were formulated. The liver, eye and caudal fin were identified biomarkers of a severe zinc deficiency. The second part of the study revealed a soybean product, treated by exogenous enzymes, had a higher phosphorus digestibility, (49.0%, vs. 36.6%) and zinc digestibility (30.7% vs. 7.9%) The treatment did not improve the protein digestibility (85%). The third part of the study showed the organic source proved more digestible than the inorganic, 37.4% and 26.9% respectively. The fish fed the organic source maintained a higher level of zinc in both the eye and caudal fin. The liver zinc levels were unaffected by both dietary level and zinc source. Analysis of the liver for a zinc dependant protein showed that under stress conditions only the organic supplemented fish were able to synthesis this protein. The analysis of the mRNA levels coding for this protein indicate the fish on both zinc forms up regulated the production of the mRNA to the same extent when stressed. Finally this study also examined the viability of using a stable isotope to identify different ‘preferences’ for one form of supplementation over the other in different tissues. This method illustrated a tissue dependant difference to how the fish attempted physiologically to compensate for zinc deficiency. The rate of turnover was fastest in the liver, then the caudal fin and then the eye, and also showed that when the diet was more deficient there was an increased ability for the tissues to take up the organic form.

<p>Populationer av öring består av både migrerande och stationära individer, och det tycks vara både genetiska och miljömässiga faktorer som påverkar en individs beslut att vandra eller ej. Syftet med denna studie var att testa vilken effekt tillgång på föda har på tillväxt och smoltifieringsprocess hos öring (Salmo trutta). Min hypotes var att öring med hög tillförsel av mat växer bättre och smoltifieras därmed inte till samma grad som öring med låg tillförsel av mat. Som en konsekvens av skillnader i mattillgång förväntades att ATPas-aktiviteten, vilken indikerar smoltstatus, var lägre vid god tillförsel av mat än vid låg tillförsel. Experimentet utfördes från november 2003 till april 2004 vid fiskeodlingen i Brattfors, Värmland, där 2+ Klarälvsöringar utsattes för tre olika födonivåer, med fyra replikat av varje födonivå. Var 4-5 vecka fångades fisken för att vägas och mätas och slutligen togs biopsi på öringens gälar för en analys av Na+,K+ -ATPas aktivitet. I slutet av experimentet klassificerades fiskarna som parr eller smolt.</p><p>Parr hade en signifikant lägre Na+, K+ -ATPas aktivitet än smolt i de tre olika födonivåerna. Na+, K+ -ATPas aktiviteten visade dock ingen signifikant skillnad mellan födonivåerna. Parr hade ökat sin vikt och längd mest i samtliga födonivåer och störst skillnad var det i den lägsta födonivån, parr hade ökat i genomsnitt 17 g och 3,5 mm mer än smolt. Av de två högsta födonivåerna var andelen klassificerade som smolt 37 % och vid den lägsta födonivån var andelen smolt 76 %.</p> / <p>Populations of brown trout consist of both migratory and resident individuals, and it is likely that both genetic and environmental factors influence the decision to migrate. The purpose of this study was to test the effect of food availability on growth and the smolting process in brown trout (Salmo trutta). My hypothesis was that brown trout subjected to a high food supply grows better and smoltifies to a lesser degree than brown trout subjected to a low food supply. As a consequence of differences in food supply I expected that ATPase-activity, which indicates smoltification status, would be lower with a high food supply than with a low supply. The experiment was run from November 2003 until April 2004 in a fish hatchery in Brattfors, Värmland, where 2+ brown trout from the river Klarälven were exposed to three food levels, each replicated four times. Every 4-5 weeks the fish were weighed and measured and a biopsy was taken from the gills for analysis of Na+, K+ -ATPase activity at the end of the experiment. At the end of the experiment the fish were classified as parr or smolt.</p><p>Parr had a significantly lower Na+, K+ -ATPase activity than smolt for the three different food treatments. Na+, K+ -ATPase activity did not differ significantly between food levels. Parr grew faster (both weight and length) than smolt at all food levels, and the largest difference between parr and smolt was observed at the lowest food level, where parr increased on average 17 g and 3,5 mm more than smolt. At the two highest food levels the proportion classified as smolt was 37 % and at the lowest foodlevel the proportion of smolt was 76 %.</p>

Cyclopropenoid fatty acids (CPFA), which are a group of fatty acids produced by plants of the order Malvales, are known to induce adverse physiological effects when administered to a variety of animal species. A structurally strained cyclopropene ring is present in all CPFA and is believed responsible for the toxic action of these fatty acids. Dietary consumption of CPFA by mammals, poultry and fish has resulted in toxic responses including hepatic damage, impaired reproductive capabilities and sizeable alterations in lipid metabolism. Furthermore, CPFA have been identified as mildly carcinogenic and strongly cocarcinogenic towards rainbow trout (Salmo gairdneri). The mechanism by which CPFA enhance carcinogenesis is currently not understood. The research in this thesis has therefore been directed toward obtaining a better understanding as to how CPFA induce toxic responses in rainbow trout. Hepatic plasma membranes were isolated from both control trout and trout which had consumed dietary CPFA. The plasma membranes were then compared via the use of electron microscopy, chromatographic analysis of phospholipid and fatty acid content, two dimensional polyacrylamide gel electrophoresis of proteins, and Western blot analysis of concanavalin A sensitive glycoproteins. Electron micrographs revealed that control plasma membranes appeared more homogeneous than CPFA membranes and were characterized by more membrane sheets and less vesicularization. The analysis of enzyme activities revealed that CPFA caused a decrease in whole liver glucose-6-phosphatase activity and that control plasma membranes expressed slightly higher glucose-6-phosphatase and 5'-nucleotidase activities as compared to CPFA membranes. Although dietary CPFA appeared to have no effect on the phospholipid content of the plasma membranes, significant alterations in the fatty acid profiles of ethanolamine and choline phospholipids were observed. CPFA caused a decrease in palmitic, palmitoleic and oleic acids while the level of stearic and docosahexaenoic acids subsequently increased. Differences between the protein content of control and CPFA plasma membranes were made clear through the analysis of electrophoretic and Western blotting data. Membranes isolated from fish fed CPFA contained several proteins of high molecular weight (above 66,000 daltons) and other proteins of high isoelectric point that were not present in control plasma membranes. Additionally, two families of glycoproteins which had previously been identified as microsomal in origin were detected only in CPFA plasma membranes. A discussion concerning the possible causes and biological ramifications of the observed subcellular alterations caused by CPFA insult is also presented in this thesis. / Graduation date: 1989